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How Big Is TON 618 Really_ · Boring Science

0:00
Speaker 1: Light from this object takes over 10 billion years to
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Speaker 1: reach us. When you look at TON 618, you're seeing
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Speaker 1: something from when the universe was barely 3 billion years old.
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Speaker 1: That single fact should tell you this isn't an ordinary
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Speaker 1: black hole. We're going to explore the actual size of
0:21
Speaker 1: TON 618, and I need to be clear from the start.
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Speaker 1: the numbers involved will challenge your ability to comprehend scale itself.
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Speaker 1: This isn't hyperbole. The human brain didn't evolve to grasp
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Speaker 1: distances measured in hundreds of billions of kilometers, or masses
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Speaker 1: equivalent to 66 billion suns. But we're going to try anyway,
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Speaker 1: using every comparison and perspective shift we can muster. By
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Speaker 1: the end of this journey, you'll understand why TON618 represents
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Speaker 1: one of the most extreme objects physics allows to exist.
1:02
Speaker 1: You'll see why it shouldn't exist at all according to
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Speaker 1: some theories, and you'll grasp why astronomers sometimes go quiet
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Speaker 1: when they talk about it, as if they've stumbled onto
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Speaker 1: something the universe forgot to keep hidden. If you find
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Speaker 1: comfort in these gentle explorations of space and science, I'd
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Speaker 1: be grateful if you'd consider subscribing and giving this video
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Speaker 1: a like. Let's start with where this monster lives. TON
1:36
Speaker 1: 618 sits near the border between two constellations you've probably
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Speaker 1: never heard of, Canes Venatici and Coma Berenices. The distance
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Speaker 1: is staggering in two different ways. The light we see
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Speaker 1: left TON 618 roughly 10.8 billion years ago. That's the
1:57
Speaker 1: light travel time. But because the universe has been expanding
2:02
Speaker 1: while that light journeyed toward us, the actual Komoving distance
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Speaker 1: is approximately 18.2 billion light years. Think about what that
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Speaker 1: means for a moment. When the light currently hitting our
2:17
Speaker 1: telescopes began its journey, Earth didn't exist. Our Sun didn't exist.
2:24
Speaker 1: The Milky Way looked completely different. Dinosaurs were still 4
2:29
Speaker 1: billion years in the future, but distance is just the
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Speaker 1: opening act. The real story is what TON618 actually is.
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Speaker 1: TON618 is classified as a quasar, specifically a hyperluminous broad
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Speaker 1: absorption line radio-loud quasar. That's a mouthful of technical terms
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Speaker 1: that each reveal something crucial. Strip away the jargon and
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Speaker 1: you're left with this. TON618 is a supermassive black hole
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Speaker 1: actively feeding on an enormous accretion disk of superheated matter,
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Speaker 1: releasing more energy than most galaxies combined, while simultaneously blasting
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Speaker 1: radio waves across the cosmos and driving powerful winds of
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Speaker 1: material away from itself at thousands of kilometers per second.
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Speaker 1: The black hole at the center is where things get
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Speaker 1: genuinely uncomfortable for our sense of scale. Mass estimates vary
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Speaker 1: depending on which measurement technique you trust. The higher estimate,
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Speaker 1: widely cited in popular sources, puts ton, 618, at 66
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Speaker 1: billion solar masses. That's 66 billion times the mass of
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Speaker 1: our sun. A more recent 2019 measurement using different spectral
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Speaker 1: lines suggests 40.7 billion solar masses. Either way, we're talking
4:02
Speaker 1: about a black hole that contains more mass than all
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Speaker 1: the stars in the entire Milky Way galaxy combined, which
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Speaker 1: clock in at around 64 billion solar masses. Let that settle.
4:17
Speaker 1: This single object, this one black hole, has more mass
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Speaker 1: packed into it than our entire galaxy's worth of stars.
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Speaker 1: To put this in perspective, compare it to Sagittarius A-star,
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Speaker 1: the supermassive black hole at the center of our own
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Speaker 1: Milky Way. Sagittarius A-star weighs in at 4.3 million solar masses.
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Speaker 1: It's not small by any standard. Its event horizon would
4:45
Speaker 1: fit inside Mercury's orbit. But TON 618 is roughly 15,300
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Speaker 1: times more massive. If Sagittarius A-star is a marble, Ton
4:59
Speaker 1: 618 is a beach ball the size of a house.
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Speaker 1: Now let's talk about the physical size, because this is
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Speaker 1: where your intuition completely fails. A black hole's size is
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Speaker 1: defined by its Schwarzschild radius, the distance from the center
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Speaker 1: to the event horizon, that point of no return where
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Speaker 1: even light cannot escape. For TON 618, this radius measures
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Speaker 1: approximately 1,300 astronomical units. One astronomical unit is the distance
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Speaker 1: from Earth to the Sun, roughly 150 million kilometers. So
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Speaker 1: we're talking about 1,300 times that distance. The event horizon diameter,
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Speaker 1: the full width across, is roughly 2,600 astronomical units, or
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Speaker 1: about 390 billion kilometers. Let me give you a reference
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Speaker 1: point that might help. Neptune, the most distant planet in
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Speaker 1: our solar system, orbits the Sun at an average distance
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Speaker 1: of 30 astronomical units. Pluto, out in the Kuiper belt,
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Speaker 1: averages about 40 astronomical units, the Kuiper Belt itself extends
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Speaker 1: to roughly 50 astronomical units. Ton 618's event horizon extends
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Speaker 1: more than 40 times farther than Neptune's orbit. You could
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Speaker 1: fit our entire solar system, from the Sun out to
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Speaker 1: the Kuiper Belt, inside Ton 618's event horizon more than
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Speaker 1: 40 times over. Line up 40 complete solar systems side
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Speaker 1: by side. and you just about span the diameter of
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Speaker 1: this black hole's point of no return. Still having trouble
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Speaker 1: visualizing it? Let's try this. Light travels at 299,792 kilometers
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Speaker 1: per second. At that speed, light takes about 8 minutes
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Speaker 1: to travel from the Sun to Earth. It takes light
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Speaker 1: about 4 hours to reach Neptune. but to cross from
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Speaker 1: one side of Ton 618's event horizon to the other
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Speaker 1: would take light, moving at the fastest speed possible in
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Speaker 1: our universe, several weeks. NASA created a visualization comparing black holes,
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Speaker 1: and when they reached Ton 618 at the end, they
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Speaker 1: noted that its shadow is so enormous that a beam
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Speaker 1: of light would take weeks to traverse it. Compare that
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Speaker 1: to M87. the famous black hole photographed by the Event
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Speaker 1: Horizon Telescope. M87' s black hole contains about 5.4 billion solar masses,
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Speaker 1: and light would take roughly two and a half days
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Speaker 1: to cross its shadow. TON 618 is in a completely
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Speaker 1: different category. The sheer scale creates a bizarre situation. If
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Speaker 1: you could somehow observe ton 618 up close, which you
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Speaker 1: absolutely could not survive, but let's pretend, the event horizon
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Speaker 1: would look more like a wall or barrier stretching infinitely
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Speaker 1: in all directions than a spherical boundary. Your human field
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Speaker 1: of view couldn't encompass enough of it to perceive the curve.
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Speaker 1: It would just be a flat black surface extending beyond
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Speaker 1: your visual horizon in every direction, with space itself warping
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Speaker 1: so severely near it that the laws of physics as
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Speaker 1: you understand them would cease to make intuitive sense. Here's
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Speaker 1: something that might disturb you. If you were falling toward TON618,
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Speaker 1: you could cross the event horizon without immediately noticing anything wrong.
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Speaker 1: The gravitational gradient, The difference in gravitational pull between your
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Speaker 1: head and feet would be relatively gentle compared to smaller
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Speaker 1: black holes. You'd pass the point of no return, still intact,
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Speaker 1: still conscious, with no immediate sensation that anything had changed.
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Speaker 1: Only later, as you continued falling, would tidal forces eventually
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Speaker 1: tear you apart, but the crossing itself, almost peaceful. Smaller
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Speaker 1: black holes rip you apart before you reach the event horizon.
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Speaker 1: TON-618 is so large that its event horizon is almost gentle.
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Speaker 1: Now let's consider what surrounds this monster. Because TON-618 doesn't
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Speaker 1: sit in empty space quietly existing, it's violently active. As
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Speaker 1: a quasar, TON618 is actively feeding. Matter spirals inward through
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Speaker 1: an accretion disk, a swirling disk of gas and dust
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Speaker 1: being pulled toward the event horizon. As this material accelerates
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Speaker 1: and compresses, friction heats it to extreme temperatures. We're talking
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Speaker 1: about millions of degrees in some regions. The accretion disk
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Speaker 1: itself would extend for light days or even light weeks
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Speaker 1: from the black hole. This superheated matter releases radiation across
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Speaker 1: the entire electromagnetic spectrum. Radiowaves, microwaves, infrared, visible light, ultraviolet, X-rays,
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Speaker 1: gamma rays. The amount of energy being released is almost incomprehensible.
10:46
Speaker 1: Ton 618 shines with a luminosity of approximately 4 times
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Speaker 1: 10 to the 40th power watts. To put that in
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Speaker 1: more familiar terms, Ton 618 is 140 trillion times brighter
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Speaker 1: than our sun. One object, outputting more light and energy
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Speaker 1: than 140 trillion suns combined. The host galaxy surrounding Ton 618,
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Speaker 1: and there must be one, because quasars sit at the
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Speaker 1: centers of galaxies, is completely outshone by the central quasar.
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Speaker 1: Despite potentially containing hundreds of billions of stars, the galaxy
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Speaker 1: is invisible from Earth. The black hole's accretion disk is
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Speaker 1: so bright that the entire galaxy is lost in the glare.
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Speaker 1: Gas is falling into ton 618, at speeds approaching 7,000
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Speaker 1: km per second. That's roughly 2.3% the speed of light.
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Speaker 1: Material is being consumed at an enormous rate, converting mass
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Speaker 1: to energy with terrifying efficiency. Some of this infalling gas
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Speaker 1: has been measured, moving at speeds up to 10,500 km
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Speaker 1: per second, about 3.5% light speed. demonstrating the immense gravitational pull.
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Speaker 1: But not everything falls in. TON 618 also drives powerful outflows.
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Speaker 1: It's classified as a broad absorption line quasar, meaning its
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Speaker 1: spectrum shows evidence of strong winds being driven away from
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Speaker 1: the black hole. Radiation pressure from the accretion disk is
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Speaker 1: so intense that it literally blows material outward at thousands
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Speaker 1: of kilometers per second. These winds carry away significant amounts
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Speaker 1: of matter and energy, potentially affecting star formation across the
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Speaker 1: entire host galaxy. TON-618 is also radio-loud, producing significant radio
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Speaker 1: emissions from relativistic jets. These are streams of charged particles,
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Speaker 1: accelerated to near-light speed, shooting outward perpendicular to the accretion disk.
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Speaker 1: the jets carry enormous energy and extend far beyond the
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Speaker 1: black hole itself, potentially reaching across hundreds of thousands of
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Speaker 1: light years. In 2021, observations from the Atacama Large Millimeter
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Speaker 1: Array revealed something remarkable. An enormous nebula of gas surrounding
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Speaker 1: Ton 618 and its host galaxy. This Lyman Alpha blob,
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Speaker 1: as it's called, has a diameter of at least 100 kiloparsecs,
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Speaker 1: about 330,000 light years. That's twice the diameter of our
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Speaker 1: entire Milky Way galaxy. This nebula consists of two parts,
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Speaker 1: an inner molecular outflow and an extensive cold molecular gas
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Speaker 1: in the circumgalactic medium. Each part has a mass of
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Speaker 1: approximately 50 billion solar masses. Combined, That's 100 billion solar
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Speaker 1: masses of gas, more massive than the black hole itself.
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Speaker 1: Both components are aligned with the radio jets, suggesting the
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Speaker 1: black hole's activity has shaped the distribution of gas on
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Speaker 1: truly galactic scales. This gas represents an enormous reservoir that
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Speaker 1: could potentially fuel future star formation or be consumed by
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Speaker 1: the black hole. The extreme radiation from Ton 618 excites
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Speaker 1: hydrogen in the nebula so intensely that it glows brightly
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Speaker 1: in the Lyman-alpha line, an ultraviolet wavelength. The nebula's existence
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Speaker 1: and structure provide crucial insights into how galaxies formed in
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Speaker 1: the early universe, and how supermassive black holes influence their surroundings.
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Speaker 1: The temperatures within TON618' s immediate environment reach approximately 38,000 degrees
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Speaker 1: Celsius in some regions, with the innermost parts of the
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Speaker 1: accretion disk potentially reaching millions of degrees. At these temperatures,
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Speaker 1: atoms are completely ionized, and matter exists in a plasma state,
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Speaker 1: emitting intense radiation. So that's the basic picture of Ton 618,
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Speaker 1: an ultra-massive black hole, possibly the most massive ever directly measured,
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Speaker 1: surrounded by a vast accretion disk releasing energy equivalent to
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Speaker 1: 140 trillion suns, driving powerful jets and winds embedded in
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Speaker 1: a nebula twice the size of our galaxy, existing at
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Speaker 1: a time when the universe was barely 3 billion years old.
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Speaker 1: But understanding the scale, really grasping it, requires more than
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Speaker 1: just numbers. In the next section, we're going to break
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Speaker 1: down exactly what those numbers mean by comparing ton 618
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Speaker 1: to objects you can actually visualize. We'll work our way
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Speaker 1: up from familiar scales to the truly cosmic, building a
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Speaker 1: ladder of comprehension that might actually let you grasp what
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Speaker 1: 66 billion solar masses really means. Because right now, even
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Speaker 1: armed with all these facts, you probably can't truly picture it.
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Speaker 1: That's what we need to fix. Let's start with something
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Speaker 1: you understand. Yourself. You're about 1.7 metres tall, maybe a
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Speaker 1: bit more or less. Hold that image. Now picture standing
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Speaker 1: next to a blue whale, 30 meters long, the largest
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Speaker 1: animal ever to exist on Earth. You'd barely reach its eye.
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Speaker 1: That's a scale jump your brain can handle. Now take
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Speaker 1: another leap. The International Space Station orbits 400 kilometers above Earth.
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Speaker 1: You'd need to stack 235,000 blue whales end-to-end to reach it.
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Speaker 1: That's starting to get difficult to visualize, but you can
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Speaker 1: still sort of imagine it, because you've seen pictures of
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Speaker 1: Earth from space. The Moon sits 384,000 kilometers away, nearly
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Speaker 1: a thousand times farther than the ISS. Here's where most
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Speaker 1: people's intuition breaks. The Sun is 150 million kilometers from Earth,
17:49
Speaker 1: one astronomical unit. That's the standard measuring stick for our
17:54
Speaker 1: solar system. Neptune, the outermost planet, orbits at 30 astronomical units.
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Speaker 1: Pluto wanders out to about 40 astronomical units at its
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Speaker 1: farthest point. The entire solar system you learned about in school,
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Speaker 1: everything from Mercury to the Kuiper belt, fits comfortably within
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Speaker 1: 50 astronomical units. Ton 618's event horizon has a radius
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Speaker 1: of 1,300 astronomical units. Read that again. The edge of
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Speaker 1: this black hole, not the accretion disk, not the surrounding nebula,
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Speaker 1: just the point of no return where even light can't escape,
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Speaker 1: extends 26 times farther than Pluto's orbit. If you place
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Speaker 1: TON 618 where our sun sits, its event horizon would
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Speaker 1: swallow every planet, every asteroid, every comet, every piece of
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Speaker 1: rock and ice in our entire solar system. and still
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Speaker 1: extend outward into empty space for another 1250 astronomical units.
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Speaker 1: But that's just the event horizon. That's not even the
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Speaker 1: full picture. Remember that accretion disk we discussed? The glowing
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Speaker 1: maelstrom of superheated matter spiralling into the black hole? It
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Speaker 1: would extend significantly farther, possibly light days or even light
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Speaker 1: weeks from the event horizon itself, We're talking about a
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Speaker 1: structure so vast that light, traveling at 300,000 kilometers per second,
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Speaker 1: would take days to cross from one side to the other.
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Speaker 1: Let's try another angle, mass. Our sun contains 99.86% of
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Speaker 1: all the mass in our solar system. Jupiter. Saturn, all
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Speaker 1: the other planets, the asteroid belt, everything, they're rounding errors
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Speaker 1: compared to the sun. The sun is basically the solar
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Speaker 1: system's mass budget. Ton 618 contains 66 billion times more
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Speaker 1: mass than that. The entire Milky Way galaxy, 200 billion
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Speaker 1: to 400 billion stars, all the gas clouds, all the dust,
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Speaker 1: all the planets orbiting all those stars, the supermassive black
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Speaker 1: hole at our galactic centre, everything, has a total stellar
20:26
Speaker 1: mass of roughly 64 billion solar masses. TON 618, a
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Speaker 1: single object, outmasses every star in our galaxy combined. Sagittarius
20:38
Speaker 1: A star, the black hole at the Milky Way's center,
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Speaker 1: weighs 4.3 million solar masses. It's massive enough to hold
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Speaker 1: our galaxy together, to orchestrate the orbits of billions of stars.
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Speaker 1: Ton 618 is 15,300 times more massive. When astronomers calculated
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Speaker 1: these numbers, they had to double-check their math. The figures
21:07
Speaker 1: seemed wrong. They still seem wrong, even though we've verified
21:12
Speaker 1: them through multiple independent methods. Here's what really breaks your brain.
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Speaker 1: Light speed comparisons. You probably know that light from the
21:23
Speaker 1: sun takes 8 minutes and 20 seconds to reach Earth.
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Speaker 1: That's the light travel distance across one astronomical unit. Light
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Speaker 1: from Neptune takes about 4 hours to reach us. the
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Speaker 1: edge of our solar system, light needs about seven hours
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Speaker 1: to get here from that far out. Ton 618's event
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Speaker 1: horizon is so enormous that a beam of light would
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Speaker 1: take weeks to traverse its diameter. Not hours, weeks. The
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Speaker 1: exact same light that crosses our entire solar system in
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Speaker 1: seven hours would need multiple weeks to travel across Ton
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Speaker 1: 618's shadows. Compare that to M87 Star, the black hole
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Speaker 1: we actually imaged with the Event Horizon Telescope in 2019,
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Speaker 1: humanity's first direct photograph of a black hole. That object
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Speaker 1: made headlines worldwide. It weighs 5.4 billion solar masses, making
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Speaker 1: it one of the largest black holes in the relatively
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Speaker 1: nearby universe. Its shadow is so large, that light takes
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Speaker 1: about two and a half days to cross it. TON
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Speaker 1: 618 is more than 10 times larger. NASA created a
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Speaker 1: visualization scaling up from small black holes to the largest
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Speaker 1: known ones. The animation starts with black holes a few
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Speaker 1: times the sun's mass, then jumps to progressively larger objects.
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Speaker 1: It works through dozens of intermediate black holes, steadily increasing
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Speaker 1: in scale. M87-star appears near the end of this progression,
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Speaker 1: dwarfing everything that came before it. The animation treats it
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Speaker 1: as one of the final boss battles of cosmic scale.
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Speaker 1: Then TON-618 appears, and M87-star looks small. Let's ground this
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Speaker 1: in something tangible. Imagine you're an astronaut approaching TON-618. You're
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Speaker 1: not falling in. You're just flying past at a safe distance,
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Speaker 1: maybe a few light years away. You point your spacecraft
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Speaker 1: toward it and start your approach at light speed. At
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Speaker 1: that distance, TON618 would appear as a point of light.
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Speaker 1: Brighter than anything in the sky, but still point-like. As
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Speaker 1: you get closer, it starts to resolve. First, you'd see
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Speaker 1: the accretion disk. a glowing spiral larger than any galaxy
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Speaker 1: you've ever observed. The light isn't white. It's shifted across
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Speaker 1: the spectrum from the intense gravitational effects. Space around the
24:13
Speaker 1: black hole is so severely warped that light from behind
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Speaker 1: it bends around to the front, creating a halo effect.
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Speaker 1: You'd see multiple distorted images of the accretion disks simultaneously.
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Speaker 1: layered over each other in impossible geometry. You're still weeks
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Speaker 1: away at light speed. Weeks. And the structure keeps growing
24:37
Speaker 1: in your field of view. The accretion disk resolves into
24:41
Speaker 1: spiral arms, each one a river of plasma hot enough
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Speaker 1: to vaporise anything that touches it. You'd see the jets,
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Speaker 1: if you looked perpendicular to the disk. Columns of matter.
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Speaker 1: accelerated to 99.9% light speed, shooting outward for hundreds of
25:01
Speaker 1: thousands of light years. But the event horizon itself? You
25:07
Speaker 1: still couldn't see it directly. It's black, perfectly, absolutely black,
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Speaker 1: because no light escapes it. You'd only see its silhouette
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Speaker 1: against the accretion disk, a spherical absence where the universe
25:22
Speaker 1: simply stops. that absence would span thousands of astronomical units.
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Speaker 1: Your entire solar system could fit in the gap between
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Speaker 1: where the accretion disk's glow ends and where space itself
25:36
Speaker 1: becomes visible again on the other side. Now consider this
25:40
Speaker 1: from another perspective. TON 618 formed when the universe was
25:46
Speaker 1: only 3 billion years old. That's less than a quarter
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Speaker 1: of the universe's current age. Somehow, In that cosmically brief period,
25:56
Speaker 1: this object accumulated 66 billion solar masses. That's not just impressive,
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Speaker 1: it's theoretically problematic. Black holes grow by accreting matter. Material
26:08
Speaker 1: spirals inward, heats up, radiates energy, and eventually crosses the
26:14
Speaker 1: event horizon. But there's a natural speed limit to this
26:17
Speaker 1: process called the Eddington limit. When matter falls into a
26:22
Speaker 1: black hole, it releases enormous energy. That energy creates radiation
26:28
Speaker 1: pressure that pushes away additional, infalling matter. The more massive
26:34
Speaker 1: the black hole, the higher its Eddington luminosity, but the
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Speaker 1: relationship is linear. Double the mass, double the maximum accretion rate.
26:45
Speaker 1: For TON 618 to reach 66 billion solar masses in
26:47
Speaker 1: 3 billion years, it would need to accrete matter at
26:54
Speaker 1: rates that challenge or exceed the Eddington limit for significant periods.
27:00
Speaker 1: Standard astrophysical models struggle to explain how this happens. Either
27:05
Speaker 1: the early universe had conditions that allowed super-Eddington accretion, or
27:11
Speaker 1: ton 618 formed from an unusually massive seed black hole.
27:17
Speaker 1: or it grew through an improbable series of mergers with
27:20
Speaker 1: other massive black holes. Possibly all three. Professor Andrew King
27:27
Speaker 1: from the University of Leicester calculated theoretical maximum masses for
27:32
Speaker 1: black holes in 2015. His work suggested that non-spinning black
27:38
Speaker 1: holes couldn't exceed 50 billion solar masses through accretion alone.
27:44
Speaker 1: The physics becomes self-limiting. radiation pressure eventually prevents further growth.
27:51
Speaker 1: Spinning black holes can reach higher masses, potentially up to
27:56
Speaker 1: 270 billion solar masses, if they're rotating extremely fast. TON
28:03
Speaker 1: 618 sits at 66 billion solar masses. If it's not
28:07
Speaker 1: spinning rapidly, it's already exceeded theoretical predictions. If it is
28:13
Speaker 1: spinning rapidly, it might still have room to grow But
28:17
Speaker 1: it's approaching the upper limits of what physics allows. We
28:22
Speaker 1: might be observing a black hole near the theoretical maximum size.
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Speaker 1: A cosmic endpoint where growth becomes impossible. That surrounding nebula, remember? 330,000
28:36
Speaker 1: light years across, containing 100 billion solar masses of gas.
28:42
Speaker 1: That's not decorative. That's fuel. That's material that could potentially
28:47
Speaker 1: feed the black hole for millions or billions of years
28:50
Speaker 1: to come. But whether TON-618 can actually consume it depends
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Speaker 1: on complex feedback mechanisms we don't fully understand. The black
29:02
Speaker 1: hole's radiation might heat and disperse the gas before it
29:06
Speaker 1: can fall in, or the gas might cool and collapse,
29:11
Speaker 1: providing sustained feeding. We're watching a cosmic drama whose ending
29:16
Speaker 1: we can't predict. Here's one more comparison that might help.
29:22
Speaker 1: Our sun will live for about 10 billion years total.
29:26
Speaker 1: It's currently halfway through that lifespan. When it dies, it'll
29:32
Speaker 1: puff off its outer layers and leave behind a white
29:35
Speaker 1: dwarf with about 60% of its current mass. roughly 0.6
29:41
Speaker 1: solar masses. That white dwarf will then cool and fade
29:46
Speaker 1: for trillions of years, eventually becoming a black dwarf, a cold,
29:52
Speaker 1: dark cinder of carbon and oxygen. TON 618 could swallow
29:56
Speaker 1: 110 billion of those dead stars and still have room
30:01
Speaker 1: for more inside its event horizon. You can't actually picture this.
30:06
Speaker 1: Your brain isn't built for it. We evolved to understand
30:10
Speaker 1: scales from centimeters to kilometers, from seconds to decades. Our
30:16
Speaker 1: intuitions work for objects we can see and time scales
30:20
Speaker 1: we can experience. When you try to visualize 66 billion
30:25
Speaker 1: solar masses or structures spanning thousands of astronomical units, You're
30:31
Speaker 1: using mental tools designed for an entirely different problem set.
30:36
Speaker 1: But now you have the scaffolding. You understand the comparisons.
30:42
Speaker 1: You know that Ton 618 outmasses our galaxy's stars combined.
30:48
Speaker 1: That its event horizon dwarfs our solar system. That light
30:52
Speaker 1: takes weeks to cross it. That it shouldn't exist according
30:56
Speaker 1: to some theoretical models, but does anyway. The numbers might
31:01
Speaker 1: not create a picture in your mind, but they create
31:04
Speaker 1: something else. Context for realising just how far beyond normal
31:09
Speaker 1: cosmic scales this object sits. And there's another element to
31:15
Speaker 1: this scale problem that makes TON618 even stranger than the
31:21
Speaker 1: numbers alone suggest. We've been talking about its mass, its size,
31:27
Speaker 1: its energy output. But we haven't talked about its age,
31:31
Speaker 1: or rather, when we're seeing it. The light reaching us
31:35
Speaker 1: from ton 618 has been travelling for 10.8 billion years.
31:42
Speaker 1: Think about what that means. When those photons left the
31:45
Speaker 1: vicinity of this monster, the universe was only 3 billion
31:49
Speaker 1: years old, barely a quarter of its current age. The
31:54
Speaker 1: sun didn't exist yet. Earth didn't exist. our entire solar
32:00
Speaker 1: system wouldn't form for another 6 billion years. We're not
32:04
Speaker 1: observing TON618 as it is now. We're observing it as
32:10
Speaker 1: it was in the cosmic equivalent of early childhood. And
32:14
Speaker 1: it was already this massive. That shouldn't be possible. Not
32:18
Speaker 1: according to our standard models of black hole formation and growth.
32:23
Speaker 1: Black holes grow primarily through two mechanisms. accreting matter from
32:28
Speaker 1: their surroundings, or merging with other black holes. Both processes
32:34
Speaker 1: take time. A lot of time. Starting from stellar mass
32:39
Speaker 1: black holes, the kind formed when massive stars collapse, you'd
32:44
Speaker 1: need incredibly efficient growth over billions of years to reach
32:48
Speaker 1: even 1 billion solar masses. Reaching 66 billion solar masses
32:55
Speaker 1: in only 3 billion years requires something far more extreme.
33:00
Speaker 1: The Eddington limit becomes crucial here. It's the point where
33:05
Speaker 1: a black hole's radiation pressure from infalling matter exactly balances
33:10
Speaker 1: the gravitational pull bringing matter in. Push beyond this limit
33:16
Speaker 1: and the radiation should blow away the very material trying
33:20
Speaker 1: to fall into the black hole, choking off further growth.
33:24
Speaker 1: It's a self-regulating mechanism that prevents black holes from growing
33:29
Speaker 1: too quickly. But TON 618 somehow bypassed this. Either it
33:36
Speaker 1: grew through super-Eddington accretion, somehow pulling in matter faster than
33:42
Speaker 1: the radiation pressure should allow, or it formed from an
33:46
Speaker 1: unusually massive seed, or it represents an improbable chain of mergers.
33:52
Speaker 1: or all three happen simultaneously. None of these explanations is
33:58
Speaker 1: particularly satisfying. Super-Eddington accretion requires special conditions we don't fully understand.
34:07
Speaker 1: Massive seed black holes from direct collapse scenarios are theoretically possible,
34:12
Speaker 1: but observationally unconfirmed, and the merger scenario requires an unlikely
34:19
Speaker 1: confluence of events. Yet here sits TON 618, challenging our
34:24
Speaker 1: theories by simply existing. The discovery history adds another layer
34:28
Speaker 1: to this puzzle. TON 618 wasn't found yesterday with cutting-edge technology.
34:36
Speaker 1: It was photographed in 1957 at the Tonantzintla Observatory in
34:41
Speaker 1: Mexico during a survey of faint blue stars. On those
34:46
Speaker 1: photographic plates, it appeared decidedly violet. unusual enough to warrant
34:52
Speaker 1: catalogue's entry number 618. But quasars hadn't been recognised as
34:59
Speaker 1: a distinct class of objects yet. That wouldn't happen until 1963.
35:03
Speaker 1: So for 13 years, TON 618 sat in a catalogue
35:04
Speaker 1: as a mysterious violet dot, its true nature unknown. In 1970,
35:08
Speaker 1: a radio survey in Bologna detected radio emissions from its location,
35:22
Speaker 1: flagging it as potentially interesting. Marie-Hélène Ulrich then obtained optical
35:27
Speaker 1: spectra at the MacDonald Observatory, revealing emission lines characteristic of quasars.
35:34
Speaker 1: Only then did astronomers realise what they were looking at.
35:38
Speaker 1: Not a faint blue star in our galaxy, but a
35:41
Speaker 1: quasar billions of light-years away, powered by a black hole
35:46
Speaker 1: of incomprehensible mass. This delayed recognition isn't unusual in astronomy.
35:54
Speaker 1: We often observe things before we understand them. But it's
35:58
Speaker 1: particularly striking with TON 618 because of what the delay represents.
36:05
Speaker 1: Humanity's gradual realization that the universe contains objects operating at
36:11
Speaker 1: scales we hadn't imagined. The brightness makes TON 618 simultaneously visible.
36:19
Speaker 1: and invisible. It shines with the luminosity of 140 trillion suns.
36:26
Speaker 1: With an absolute magnitude of negative 30.7, it's one of
36:31
Speaker 1: the brightest objects in the known universe. But that brilliance
36:37
Speaker 1: comes entirely from the accretion disk and surrounding material, not
36:42
Speaker 1: from stars in the host galaxy. In fact, we can't
36:46
Speaker 1: see the host galaxy at all, It's completely outshone by
36:51
Speaker 1: the central quasar, potentially hundreds of billions of stars, rendered
36:57
Speaker 1: invisible by the light from matter falling into the black hole.
37:01
Speaker 1: The galaxy exists, it has to, as galaxies host these
37:06
Speaker 1: supermassive black holes, but it's lost in the glare. That
37:12
Speaker 1: accretion disk deserves closer attention. Picture a structure extending light
37:18
Speaker 1: days or light weeks from the black hole, where matter
37:22
Speaker 1: spirals inward at velocities approaching 7,000 km per second. That's
37:28
Speaker 1: over 2% the speed of light. The friction and compression
37:32
Speaker 1: heat this material to millions of degrees. At those temperatures,
37:38
Speaker 1: atoms are completely ionized. Electrons are stripped away, leaving bare
37:43
Speaker 1: nuclei colliding at relativistic speeds. the innermost regions reach the
37:49
Speaker 1: highest temperatures, potentially tens of millions of degrees near the
37:54
Speaker 1: event horizon, where orbital velocities peak. This superheated plasma radiates
38:01
Speaker 1: across the entire electromagnetic spectrum. Radio waves, infrared, visible light, ultraviolet, X-rays,
38:12
Speaker 1: gamma rays. Every wavelength tells us something about the physical
38:17
Speaker 1: conditions at different locations in the disk. The spectrum of
38:22
Speaker 1: ton 618 shows unusually wide emission lines. These lines come
38:28
Speaker 1: from gas in what's called the broad line region, located
38:33
Speaker 1: beyond the accretion disk, but still within the black hole's
38:36
Speaker 1: gravitational influence. The width of these lines indicates velocity. The
38:42
Speaker 1: faster the gas moves, the more the emission lines are
38:46
Speaker 1: Doppler shifted, creating broader features in the spectrum. Measurements show
38:52
Speaker 1: gas velocities reaching 10,500 km per second in some regions.
38:59
Speaker 1: That's 3.5% the speed of light. This extreme velocity provides
39:05
Speaker 1: one of the key methods for estimating the black hole's mass.
39:09
Speaker 1: The faster gas must orbit to avoid falling in, the
39:13
Speaker 1: stronger the gravitational force, which directly relates to the central mass.
39:19
Speaker 1: Different research teams have used different spectral lines to estimate
39:23
Speaker 1: Ton 618's mass, yielding different results. The original estimates using
39:31
Speaker 1: hydrogen beta emission lines suggested 66 billion solar masses. More
39:38
Speaker 1: recent measurements using carbon 4 emission lines produced a lower estimate, 40.7
39:43
Speaker 1: billion solar masses. Both measurements use the same underlying data,
39:50
Speaker 1: but different calibration methods and assumptions. This uncertainty matters. If
39:57
Speaker 1: TON 618 is only 40 billion solar masses, it's still
40:03
Speaker 1: extraordinarily massive, but falls within some theoretical predictions. At 66
40:10
Speaker 1: billion solar masses, It exceeds certain theoretical limits for non-spinning
40:15
Speaker 1: black holes, making it even more problematic for standard models.
40:20
Speaker 1: The truth probably lies somewhere in that range, but the
40:24
Speaker 1: uncertainty reflects fundamental challenges in measuring black hole masses at
40:30
Speaker 1: such extreme distances. We're not weighing these objects directly. were
40:36
Speaker 1: inferring their masses from the motion of surrounding gas, which
40:40
Speaker 1: requires assumptions about the geometry, viewing angle, and dynamical state
40:46
Speaker 1: of the system. Beyond the accretion disk and broadline region
40:51
Speaker 1: lies something even more remarkable, the Lyman-alpha nebula discovered through
40:58
Speaker 1: observations with the Atacama Large Millimeter Array in 2021. This
41:05
Speaker 1: structure spans at least 330,000 light years, twice the diameter
41:11
Speaker 1: of the Milky Way. It consists of two distinct components,
41:16
Speaker 1: an inner molecular outflow, likely driven by winds from the
41:20
Speaker 1: accretion disk and jets from near the black hole, and
41:25
Speaker 1: an extensive region of cold molecular gas in the circumgalactic medium,
41:31
Speaker 1: the diffuse halo of material surrounding the galaxy. Each component
41:36
Speaker 1: contains roughly 50 billion solar masses of gas. Combined, that's
41:42
Speaker 1: 100 billion solar masses, more than the black hole itself.
41:47
Speaker 1: This nebula isn't just decoration. It's evidence of the black
41:51
Speaker 1: hole's influence extending across galactic scales. The intense ultraviolet radiation
41:58
Speaker 1: from the quasar ionizes hydrogen in the nebula, causing it
42:03
Speaker 1: to emit the Lyman-alpha line, a specific ultraviolet wavelength. This
42:09
Speaker 1: emission is so strong that TON618 is classified as a
42:14
Speaker 1: Lyman alpha blob, one of the largest such objects known.
42:19
Speaker 1: The alignment of the nebula with the radio jets suggests
42:23
Speaker 1: a physical connection. Jets are narrow beams of charged particles
42:28
Speaker 1: accelerated to near light speed, shooting outward perpendicular to the
42:33
Speaker 1: accretion disk. For TON 618, these jets carry enormous energy
42:40
Speaker 1: and momentum, potentially shaping how gas is distributed across hundreds
42:45
Speaker 1: of thousands of light years. This interaction between the black
42:49
Speaker 1: hole and its environment represents feedback. The black hole affects
42:54
Speaker 1: its surroundings, which in turn affects how much matter can
42:58
Speaker 1: fall back into the black hole. Strong feedback can regulate
43:03
Speaker 1: or even halt black hole growth, by heating and dispersing
43:06
Speaker 1: the gas that would otherwise feed it. Whether TON-618 is
43:12
Speaker 1: currently in a feedback-limited state or still growing actively remains unclear.
43:19
Speaker 1: The surrounding nebula contains enough material to fuel continued growth
43:23
Speaker 1: for millions or billions of years. But whether that material
43:28
Speaker 1: can actually reach the black hole depends on complex processes
43:32
Speaker 1: we don't fully understand. TON618 is also classified as radio-loud,
43:39
Speaker 1: meaning it produces substantial radio emissions beyond what comes from
43:44
Speaker 1: the accretion disk alone. This radio emission originates from the jets,
43:50
Speaker 1: where magnetic fields accelerate electrons to relativistic speeds. As these
43:56
Speaker 1: electrons spiral around magnetic field lines, they emit synchrotron radiation.
44:03
Speaker 1: predominantly in radio wavelengths, but extending into other parts of
44:07
Speaker 1: the spectrum. The jets themselves are poorly understood. We know
44:13
Speaker 1: they exist because we detect their radiation. We know they
44:18
Speaker 1: carry substantial energy because the radio emission is so strong.
44:23
Speaker 1: But the exact mechanism that launches them remains debated. It
44:28
Speaker 1: involves the black hole's spin, magnetic fields, threading the accretion
44:33
Speaker 1: disk and the extraction of rotational energy from the black
44:37
Speaker 1: hole itself through a process called the Blanford-Zenajek mechanism. For
44:42
Speaker 1: TON 618, the jets are aligned with the nebula structure,
44:48
Speaker 1: suggesting they've been active long enough to shape their environment significantly.
44:53
Speaker 1: These outflows can suppress star formation by heating gas and
44:58
Speaker 1: preventing it from collapsing into stars. They can also trigger
45:03
Speaker 1: star formation in some regions by compressing gas clouds. The
45:08
Speaker 1: net effect depends on local conditions and the jet's power.
45:13
Speaker 1: TON618 also shows broad absorption lines in its spectrum, another
45:19
Speaker 1: classification tag. These absorption features indicate high-velocity winds flowing outward
45:26
Speaker 1: from the quasar, likely driven by radiation pressure. These winds
45:31
Speaker 1: can reach thousands of kilometers per second, carrying away substantial
45:37
Speaker 1: amounts of matter and energy. This outflow represents yet another
45:42
Speaker 1: feedback mechanism. As the black hole accretes matter and releases energy,
45:48
Speaker 1: some of that energy drives winds that expel material, potentially
45:53
Speaker 1: limiting how much can fall in. Over cosmic time, This
45:58
Speaker 1: feedback may be why supermassive black holes and their host
46:02
Speaker 1: galaxies show correlated properties. The black hole's growth and the
46:08
Speaker 1: galaxy's evolution are intimately linked through these feedback processes. Studying
46:14
Speaker 1: TON-618 in detail presents significant observational challenges. Its extreme distance
46:22
Speaker 1: makes it appear faint despite its intrinsic brightness. The redshift
46:27
Speaker 1: stretches all wavelengths. Ultraviolet light is shifted into the visible range,
46:34
Speaker 1: visible light into infrared, and so on. This complicates observations,
46:40
Speaker 1: but also provides opportunities, as the redshift moves some spectral
46:45
Speaker 1: features that would normally be blocked by Earth's atmosphere into
46:50
Speaker 1: observable wavelengths. The host galaxy remains invisible. outshone by the quasar.
46:58
Speaker 1: Current technology can't separate the galaxy's starlight from the overwhelming
47:04
Speaker 1: glare of the central engine. Future telescopes, like the James
47:09
Speaker 1: Webb Space Telescope or planned extremely large telescopes, may eventually
47:14
Speaker 1: resolve details about the host galaxy's stellar population, mass, and structure.
47:21
Speaker 1: What we do know is that TON618 represents a crucial
47:26
Speaker 1: window into the early universe. Quasars were much more common
47:31
Speaker 1: when the universe was young, during an era of rapid
47:35
Speaker 1: galaxy formation and black hole growth. As the universe aged
47:40
Speaker 1: and expanded, galaxies consumed or dispersed much of their gas,
47:46
Speaker 1: reducing fuel availability. Quasar activity declined as a result. Modern
47:53
Speaker 1: galaxies typically have quiet supermassive black holes, accreting slowly if
47:58
Speaker 1: at all. Our own Sagittarius A star is relatively inactive,
48:03
Speaker 1: consuming matter at a modest rate. But in Ton 618's era,
48:09
Speaker 1: conditions favoured active growth. Galaxies were forming and merging frequently.
48:15
Speaker 1: Gas was abundant. Black holes grew rapidly, powering brilliant quasars
48:20
Speaker 1: visible across the cosmos. TON-618 catches this process near its peak,
48:27
Speaker 1: showing us what the universe looked like during this transformative period.
48:33
Speaker 1: The fact that such massive black holes existed so early
48:37
Speaker 1: constrains models of cosmic evolution. It tells us about initial
48:43
Speaker 1: conditions in the universe, about how matter was distributed, about
48:48
Speaker 1: how quickly structures formed. It tells us about the physics
48:53
Speaker 1: of black hole formation, in conditions vastly different from today's universe.
48:59
Speaker 1: But here's something that doesn't quite add up. TON 618
49:05
Speaker 1: shouldn't exist, at least not according to some of our models.
49:11
Speaker 1: The universe was only 3 billion years old when TON
49:14
Speaker 1: 618 looked the way we see it now. That's barely
49:19
Speaker 1: enough time for galaxies to form, let alone for a
49:22
Speaker 1: black hole to accumulate 40 to 66 billion solar masses.
49:29
Speaker 1: Standard accretion theory predicts growth rates that simply can't produce
49:33
Speaker 1: something this massive this quickly. The math doesn't work. Think
49:38
Speaker 1: about it this way. Black holes grow by consuming matter.
49:44
Speaker 1: But there's a natural speed limit to this process called
49:47
Speaker 1: the Eddington limit. When matter falls toward a black hole,
49:52
Speaker 1: it heats up and releases radiation. That radiation pushes outward.
49:58
Speaker 1: At some point, the outward radiation pressure equals the inward
50:02
Speaker 1: gravitational pull. The system reaches equilibrium. Matter can't fall in
50:09
Speaker 1: faster than the radiation can escape. This sets a maximum
50:13
Speaker 1: growth rate. Even starting from a stellar mass black hole,
50:18
Speaker 1: say 100 solar masses, and accreting at the Eddington limit
50:23
Speaker 1: continuously for 3 billion years, you'd only reach a few
50:27
Speaker 1: billion solar masses, not 40 billion, not 66 billion. The
50:33
Speaker 1: timeline doesn't allow it. So how did ton 618 get
50:38
Speaker 1: so big so fast? Several theories attempt to explain this puzzle.
50:44
Speaker 1: One possibility involves direct collapse. Instead of forming from a
50:49
Speaker 1: stellar remnant, perhaps some primordial black holes formed when massive
50:54
Speaker 1: gas clouds in the early universe collapsed directly, bypassing the
50:59
Speaker 1: stellar phase entirely. These seeds would start much heavier. maybe 10,000
51:06
Speaker 1: or even 100,000 solar masses. That gives them a head start.
51:11
Speaker 1: Another idea suggests super-Eddington accretion. Maybe under the right conditions,
51:17
Speaker 1: black holes can temporarily exceed the Eddington limit. The early
51:23
Speaker 1: universe was dense with gas. Perhaps TON618 found itself in
51:29
Speaker 1: an environment so rich with fuel that it gorged itself.
51:33
Speaker 1: growing faster than the standard limits predict. Some simulations show
51:39
Speaker 1: this might work if the accretion disk is geometrically thick
51:43
Speaker 1: and radiation escapes preferentially in certain directions rather than pushing
51:48
Speaker 1: uniformly outward. There's also the merger scenario. If multiple black
51:54
Speaker 1: holes formed early and merged repeatedly, they could build mass
51:58
Speaker 1: more quickly than accretion alone allows. Each merger adds the
52:03
Speaker 1: combined mass instantly, without needing to wait for gas to
52:08
Speaker 1: spiral in. A series of such mergers, combined with steady
52:13
Speaker 1: accretion between events, might produce an ultra-massive black hole within
52:18
Speaker 1: the available time. None of these explanations is entirely satisfying.
52:24
Speaker 1: Each has problems. Direct collapse requires very specific conditions that
52:30
Speaker 1: may not have been common. Super-Eddington accretion faces theoretical challenges
52:36
Speaker 1: about stability and radiation escape. Mergers require an improbably high
52:42
Speaker 1: rate of collisions early on. Yet TON-618 exists. The Universe
52:49
Speaker 1: doesn't care about our theoretical difficulties. This brings us to
52:54
Speaker 1: another fascinating aspect of TON-618. It might be approaching its
53:00
Speaker 1: maximum possible mass In 2015, astrophysicist Andrew King calculated theoretical
53:08
Speaker 1: mass limits for black holes based on accretion physics. He
53:13
Speaker 1: found that for a non-spinning black hole, the maximum mass
53:17
Speaker 1: achievable through accretion is roughly 50 billion solar masses. If
53:23
Speaker 1: the black hole spins rapidly in the same direction as
53:26
Speaker 1: its accretion disk, this limit increases. potentially to 270 billion
53:33
Speaker 1: solar masses. The reason involves the innermost stable circular orbit.
53:39
Speaker 1: As a black hole gains mass, this orbit moves outward. Eventually,
53:45
Speaker 1: it reaches a point where the gravitational pull at the
53:49
Speaker 1: I-S-C-O isn't strong enough to hold gas together against its
53:55
Speaker 1: own self-gravity. The disk becomes unstable, and can't deliver matter
54:00
Speaker 1: to the black hole efficiently. Growth stalls. Ton 618, with
54:06
Speaker 1: mass estimates ranging from 40.7 to 66 billion solar masses,
54:12
Speaker 1: sits right at or above King's limit for non-spinning black holes.
54:17
Speaker 1: If the higher mass estimate is correct, Ton 618 might
54:22
Speaker 1: already be near its accretion-based growth ceiling. It could be
54:26
Speaker 1: one of the most massive black holes physically possible through
54:29
Speaker 1: this mechanism. But black holes can still grow through mergers.
54:35
Speaker 1: When two black holes orbit each other and eventually collide,
54:40
Speaker 1: they combine their masses. This process doesn't face the same
54:45
Speaker 1: radiation pressure constraints as accretion. So even if ton 618
54:52
Speaker 1: has maxed out its accretion potential, It could continue growing
54:58
Speaker 1: by consuming other black holes. Of course, there's competition for
55:02
Speaker 1: the title of largest black hole. Phoenix A, another ultra-massive
55:07
Speaker 1: black hole, has been cited with mass estimates around 100
55:12
Speaker 1: billion solar masses. However, that measurement carries significant uncertainty. Different
55:21
Speaker 1: techniques and assumptions produce different results. The black hole at
55:25
Speaker 1: the centre of the Phoenix Cluster is enormous, but pinning
55:29
Speaker 1: down its exact mass remains challenging. Another contender is the
55:34
Speaker 1: black hole in the quasar SDSSJ 140821.67 plus 0 25733.2.
55:37
Speaker 1: Try saying that three times fast. Its mass estimates also
55:40
Speaker 1: reach extreme values, though again with substantial uncertainty. The competition
55:56
Speaker 1: for largest black hole depends heavily on measurement techniques and
56:01
Speaker 1: which data sets you trust. Recently, in 2025, astronomers discovered
56:08
Speaker 1: what they're calling the cosmic horseshoe black hole, weighing in
56:13
Speaker 1: at 36 billion solar masses. This discovery used a combination
56:19
Speaker 1: of gravitational lensing and stellar kinematics. a technique that provides
56:25
Speaker 1: more direct mass measurements than spectroscopic methods alone. The cosmic
56:31
Speaker 1: horseshoe ranks among the top ten most massive black holes known,
56:36
Speaker 1: possibly top five. But even at 36 billion solar masses,
56:41
Speaker 1: it's still smaller than TON618' s estimates. The difficulties in precisely
56:47
Speaker 1: measuring black hole masses mean rankings can shift. New techniques emerge.
56:54
Speaker 1: old measurements get revised. What's clear is that TON 618
56:59
Speaker 1: remains a top contender, consistently appearing in discussions of the
57:04
Speaker 1: universe's most massive black holes. What about its size? Not
57:10
Speaker 1: its mass, but its physical dimensions? The event horizon of
57:15
Speaker 1: a black hole scales with its mass. For TON 618,
57:21
Speaker 1: the Schwarzschild radius The distance from the centre to the
57:25
Speaker 1: event horizon is approximately 1,300 astronomical units. Remember, 1 AU
57:34
Speaker 1: is the distance from Earth to the Sun, about 150
57:37
Speaker 1: million kilometres. TON618' s event horizon extends 1,300 times that distance.
57:42
Speaker 1: To put it another way, The event horizon's diameter is
57:52
Speaker 1: roughly 2,600 astronomical units. Neptune orbits the Sun at about
57:58
Speaker 1: 30 astronomical units. TON 618 could swallow our entire solar system,
58:05
Speaker 1: out past Neptune, past the Kuiper belt, more than 40
58:09
Speaker 1: times over. Its event horizon is larger than the orbits
58:13
Speaker 1: of all our planets combined, with room to spare. NASA
58:18
Speaker 1: created a visualization comparing black hole sizes. It starts with
58:23
Speaker 1: stellar mass black holes, moves through Sagittarius A star at
58:28
Speaker 1: the Milky Way's center, continues to M87' s black hole, the
58:33
Speaker 1: one famously imaged by the Event Horizon Telescope, and ends
58:38
Speaker 1: with TON618. M87' s black hole has an updated mass of 5.4
58:47
Speaker 1: billion solar masses. Its shadow is so large that a
58:51
Speaker 1: beam of light travelling at 300,000 km per second would
58:56
Speaker 1: take about two and a half days to cross it.
58:59
Speaker 1: TON-618's shadow dwarfs even that. Light would take weeks to
59:05
Speaker 1: traverse it. Weeks. Think about what that means. Light circles
59:12
Speaker 1: Earth's equator more than seven times in one second. Yet
59:16
Speaker 1: it would need weeks to cross Ton 618's shadow. The
59:20
Speaker 1: scale defies comprehension. This shadow, the apparent size of the
59:25
Speaker 1: event horizon as seen by a distant observer, is actually
59:30
Speaker 1: larger than the Schwarzschild radius due to gravitational lensing. The
59:35
Speaker 1: intense gravity bends light around the black hole, creating an
59:40
Speaker 1: optical illusion that makes the shadow appear bigger. For TON 618,
59:47
Speaker 1: this effect amplifies an already incomprehensible size into something even
59:53
Speaker 1: more extreme. Standing on a planet orbiting TON 618, If
59:59
Speaker 1: such a planet could exist, you'd see a region of
1:00:03
Speaker 1: absolute blackness dominating the sky. Not just a dark spot.
1:00:09
Speaker 1: A void so vast it would cover a significant fraction
1:00:13
Speaker 1: of the visible sky, surrounded by a ring of tortured,
1:00:17
Speaker 1: red-shifted light from the accretion disk wrapping around the event
1:00:21
Speaker 1: horizon's curve. Of course, you couldn't actually stand there. The
1:00:27
Speaker 1: tidal forces would tear you apart long before you got close.
1:00:31
Speaker 1: The radiation would cook you. The environment is utterly hostile
1:00:36
Speaker 1: to any conceivable form of life. But as a thought experiment,
1:00:41
Speaker 1: it illustrates the sheer presence such an object would have.
1:00:46
Speaker 1: Inside the event horizon, causality breaks down. All paths lead inward.
1:00:53
Speaker 1: You can no more avoid falling toward the singularity then
1:00:57
Speaker 1: you can avoid moving forward in time. The singularity itself,
1:01:02
Speaker 1: the point of infinite density at the black hole's core,
1:01:06
Speaker 1: remains hidden from view, shielded by the event horizon. We
1:01:11
Speaker 1: can't observe it directly. General relativity predicts its existence, but
1:01:16
Speaker 1: also suggests our equations break down there, requiring a theory
1:01:21
Speaker 1: of quantum gravity we don't yet have. TON 618's temperature
1:01:26
Speaker 1: profile offers another window into its extremes. The accretion disk's
1:01:31
Speaker 1: emissions reveal temperatures around 38,000 degrees Celsius. That's the temperature
1:01:37
Speaker 1: of gas in the outer regions of the disk, already
1:01:40
Speaker 1: hot enough to ionize atoms and produce intense ultraviolet radiation.
1:01:47
Speaker 1: Closer to the black hole, temperatures climb even higher, millions
1:01:51
Speaker 1: of degrees. At those temperatures, matter exists in a plasma state.
1:01:57
Speaker 1: Electrons are stripped from atoms. The gas emits X-rays and
1:02:02
Speaker 1: gamma rays. This temperature gradient drives the luminosity. Hotter regions
1:02:08
Speaker 1: emit more energy. The inner disk, where temperatures peak, produces
1:02:14
Speaker 1: the most intense radiation. As matter spirals inward, it releases
1:02:19
Speaker 1: gravitational potential energy. For tons 618. This process converts mass
1:02:27
Speaker 1: to energy with extraordinary efficiency, far better than nuclear fusion.
1:02:33
Speaker 1: That's why quasars shine so brilliantly despite their compact size.
1:02:39
Speaker 1: The alignment of Ton 618's radio jets with its nebula
1:02:43
Speaker 1: suggests a long period of sustained activity. Jets don't form instantly.
1:02:50
Speaker 1: They require stable accretion and a strong magnetic field maintained
1:02:54
Speaker 1: over time. The fact that the nebula structure mirrors the
1:02:58
Speaker 1: jet orientation indicates these outflows have been shaping their environment
1:03:03
Speaker 1: for millions, possibly tens of millions of years. TON 618
1:03:09
Speaker 1: isn't a brief flare. It's a persistent, powerful engine that
1:03:14
Speaker 1: has been running for a significant fraction of cosmic history.
1:03:18
Speaker 1: This persistence raises interesting questions about duty cycles. Quasars don't
1:03:24
Speaker 1: stay active forever. Fuel supplies run low. Feedback mechanisms shut
1:03:30
Speaker 1: down accretion. The quasar phase ends, leaving behind a dormant,
1:03:35
Speaker 1: supermassive black hole. How long does TON618 have left? Is
1:03:42
Speaker 1: it near the end of its active phase, or just
1:03:45
Speaker 1: getting started? We can't say for certain, But given its
1:03:49
Speaker 1: enormous mass and the vast reservoir of gas in the
1:03:52
Speaker 1: surrounding nebula, Tarn 618 likely has fuel for continued activity
1:03:58
Speaker 1: for some time yet. When Tarn 618 eventually runs out
1:04:04
Speaker 1: of easily accessible fuel, it will fade. The accretion disk
1:04:09
Speaker 1: will thin. The jets will weaken and shut off. The
1:04:13
Speaker 1: brilliant quasar will dim, revealing the host galaxy. that currently
1:04:18
Speaker 1: remains hidden beneath the glare. At that point, TON618 will
1:04:24
Speaker 1: resemble the quiet supermassive black holes we see in modern galaxies,
1:04:30
Speaker 1: massive but dormant, waiting for a fresh supply of gas
1:04:33
Speaker 1: to reignite. That future state represents the endpoint of quasar evolution.
1:04:40
Speaker 1: All modern galaxies with supermassive black holes likely went through
1:04:45
Speaker 1: quasar phases in their youth, Sagittarius A-star at the Milky
1:04:51
Speaker 1: Way's center probably shone as a quasar billions of years ago.
1:04:56
Speaker 1: Now it's quiet, accreting slowly, producing only faint emissions. TON
1:05:04
Speaker 1: 618 shows us what our galaxy's core might have looked
1:05:07
Speaker 1: like in its prime, a blazing beacon visible across the universe.
1:05:13
Speaker 1: This evolutionary trajectory connects TON 618 to every massive galaxy
1:05:18
Speaker 1: we observe today. The correlation between black hole mass and
1:05:23
Speaker 1: galactic properties isn't coincidental. Supermassive black holes and their host
1:05:29
Speaker 1: galaxies grow together through a process called coevolution. When a
1:05:34
Speaker 1: quasar blazes at full power, its radiation and jets heat
1:05:39
Speaker 1: surrounding gas, preventing it from cooling and forming stars. This
1:05:45
Speaker 1: feedback mechanism regulates both star formation and black hole growth.
1:05:50
Speaker 1: Without it, galaxies would convert gas into stars too quickly,
1:05:56
Speaker 1: exhausting their fuel supply and looking nothing like the galaxies
1:06:00
Speaker 1: we observe. TON 618 exemplifies this process in action. Its
1:06:06
Speaker 1: powerful jets inject energy into the surrounding medium. The Lyman-alpha
1:06:12
Speaker 1: nebula shows clear signs of this interaction, Gas heated and
1:06:17
Speaker 1: ionized by radiation. Structures aligned with jet directions. Velocities consistent
1:06:23
Speaker 1: with outflows. The black hole isn't just consuming gas. It's
1:06:29
Speaker 1: reshaping its entire environment, determining what gas cools and forms stars,
1:06:36
Speaker 1: what gas gets heated and dispersed, what structures emerge from
1:06:40
Speaker 1: the cosmic raw materials. This feedback operates on multiple scales simultaneously.
1:06:48
Speaker 1: Close to the black hole, within the accretion disk, temperatures
1:06:53
Speaker 1: reach millions of degrees. Radiation pressure becomes so intense, it
1:06:59
Speaker 1: can reverse the inflow, creating winds that blow material away.
1:07:04
Speaker 1: Farther out, jets deposit energy across hundreds of thousands of
1:07:09
Speaker 1: light years. Even farther, at megaparsec scales, the cumulative effect
1:07:15
Speaker 1: of many quasars heats the intergalactic medium, affecting cosmic structure
1:07:21
Speaker 1: formation itself. The efficiency of this process depends critically on
1:07:26
Speaker 1: the Eddington limit, the balance point between gravity pulling matter
1:07:30
Speaker 1: inward and radiation pressure pushing it outward. For a black
1:07:36
Speaker 1: hole of ton 618's mass, The Eddington luminosity is enormous,
1:07:42
Speaker 1: roughly 10 to the power of 40 watts. TON 618
1:07:47
Speaker 1: shines at approximately four times that value, suggesting super Eddington accretion.
1:07:53
Speaker 1: How does it manage this? Several mechanisms might enable super
1:07:59
Speaker 1: Eddington rates. If the accretion disk is geometrically thick rather
1:08:04
Speaker 1: than thin, radiation can escape along the poles while matter
1:08:09
Speaker 1: continues flowing in along the equator. If the accretion flow
1:08:15
Speaker 1: is clumpy rather than smooth, dense clumps can shield material
1:08:20
Speaker 1: behind them from radiation pressure. If the black hole is
1:08:24
Speaker 1: spinning rapidly, frame-dragging effects near the event horizon can extract
1:08:29
Speaker 1: rotational energy, supplementing the luminosity without requiring more accretion. TON618' s
1:08:39
Speaker 1: spin remains unknown. Measuring black hole spin requires observing features
1:08:45
Speaker 1: near the event horizon, the innermost stable circular orbit, relativistic
1:08:51
Speaker 1: line profiles, or spin-dependent efficiency of accretion. For an object 10.8
1:08:58
Speaker 1: billion light away, these measurements exceed current capabilities. We can
1:09:05
Speaker 1: only infer spin indirectly from luminosity and accretion signatures. But
1:09:12
Speaker 1: spin matters enormously for maximum mass. Andrew King's theoretical work
1:09:18
Speaker 1: showed that a non-spinning black hole growing through accretion should
1:09:22
Speaker 1: max out around 50 billion solar masses. Beyond that mass,
1:09:28
Speaker 1: the innermost stable circular orbit moves outward, past the point
1:09:32
Speaker 1: where gas self-gravity can hold it together. The accretion disk fragments.
1:09:38
Speaker 1: Growth stalls. However, a rapidly spinning black hole aligned with
1:09:44
Speaker 1: its accretion disk can reach masses up to 270 billion
1:09:49
Speaker 1: solar masses before hitting this limit. Ton, 618's mass, whether 40.7
1:09:58
Speaker 1: billion or 66 billion solar masses depending on the measurement,
1:10:04
Speaker 1: places it near or potentially above the non-spinning limit. If
1:10:09
Speaker 1: the higher mass estimate is correct, ton 618 must be
1:10:14
Speaker 1: spinning significantly, If the lower estimate holds, it might be
1:10:19
Speaker 1: approaching its maximum size regardless of spin. Either way, TON618
1:10:26
Speaker 1: likely won't grow much larger through accretion alone. Mergers offer
1:10:31
Speaker 1: an alternative growth path. When two black holes orbit each other,
1:10:36
Speaker 1: they lose energy to gravitational waves and eventually merge. The
1:10:42
Speaker 1: resulting black hole has mass equal to the sum of
1:10:45
Speaker 1: the original masses minus the energy radiated as gravitational waves,
1:10:50
Speaker 1: typically a few percent. For supermassive black holes like those
1:10:56
Speaker 1: in TON618' s mass range, mergers could add tens of billions
1:11:01
Speaker 1: of solar masses in a single event. The early universe,
1:11:05
Speaker 1: when TON618 was active, experienced higher galaxy merger rates than
1:11:12
Speaker 1: galaxies were closer together. Dark matter halos were still assembling.
1:11:18
Speaker 1: Major mergers happened frequently. Each merger brought gas to fuel
1:11:23
Speaker 1: the quasar, and potentially delivered another supermassive black hole to
1:11:28
Speaker 1: merge with the central one. This environment favoured rapid black
1:11:34
Speaker 1: hole growth through both accretion and mergers, but mergers also
1:11:38
Speaker 1: posed challenges. When two supermassive black holes enter the same galaxy,
1:11:44
Speaker 1: they don't immediately merge. They must first sink to the
1:11:48
Speaker 1: galactic centre through dynamical friction, interactions with stars and gas
1:11:54
Speaker 1: that extract energy and angular momentum. This process works well initially,
1:12:01
Speaker 1: but slows as the black holes form a bound binary.
1:12:05
Speaker 1: Getting from a wide binary separation down to merger requires
1:12:09
Speaker 1: additional mechanisms. Interactions with a third black hole, a dense
1:12:14
Speaker 1: stellar cusp, or a circumbinary gas disk. This final parsec
1:12:21
Speaker 1: problem has puzzled theorists for decades. Some massive black hole
1:12:27
Speaker 1: binaries might stall at separations of about a parsec, never
1:12:32
Speaker 1: merging on timescales shorter than the age of the universe.
1:12:36
Speaker 1: If true, This would limit how quickly black holes can
1:12:40
Speaker 1: grow through mergers. However, recent simulations suggest that in gas-rich
1:12:45
Speaker 1: early universe conditions, circumbinary disks provide sufficient torque to drive mergers.
1:12:52
Speaker 1: Ton 618 might have grown partly through such mergers. The
1:12:59
Speaker 1: broad absorption line features in ton 618's spectrum hint at
1:13:05
Speaker 1: powerful outflows. These absorption lines appear blue-shifted, shifted to shorter wavelengths,
1:13:14
Speaker 1: indicating material moving toward us at high velocities. The gas
1:13:20
Speaker 1: absorbs specific wavelengths from the quasar's light, creating dark lines
1:13:26
Speaker 1: in the spectrum. The width and velocity of these lines
1:13:31
Speaker 1: reveal outflow speeds reaching thousands of kilometers per second. These
1:13:36
Speaker 1: outflows aren't accretion disk winds alone. They're large-scale galactic winds
1:13:42
Speaker 1: driven by radiation pressure and jets. Gas accelerated to these
1:13:47
Speaker 1: velocities carries enormous kinetic energy, enough to heat the surrounding
1:13:52
Speaker 1: medium and potentially expel it from the galaxy entirely. This
1:13:58
Speaker 1: represents the feedback mechanism in its most direct form. the
1:14:02
Speaker 1: black hole literally blowing away its own fuel supply. The
1:14:07
Speaker 1: mass outflow rate can be estimated from the absorption line properties.
1:14:12
Speaker 1: For Ton 618, outflows likely carry away hundreds to thousands
1:14:18
Speaker 1: of solar masses per year. Compare this to the accretion
1:14:23
Speaker 1: rate needed to power the quasar, several hundred solar masses
1:14:27
Speaker 1: per year based on luminosity. The outflow and accretion rates
1:14:33
Speaker 1: are comparable. For every bit of matter the black hole consumes,
1:14:37
Speaker 1: roughly an equal amount gets expelled. This balance determines the
1:14:42
Speaker 1: system's evolution. If outflows exceed accretion too much, the quasar
1:14:47
Speaker 1: starves and shuts down. If accretion dominates, the black hole
1:14:52
Speaker 1: grows without limit. The fact that we observe TON618 in
1:14:58
Speaker 1: a roughly balanced state suggests self-regulation. The quasar adjusts its
1:15:05
Speaker 1: own fuel supply through feedback, maintaining conditions where it can
1:15:10
Speaker 1: shine brightly without either exhausting its gas reservoir too quickly
1:15:16
Speaker 1: or growing uncontrollably. The radio-loud classification indicates significant jet power.
1:15:23
Speaker 1: Only about 10% of quasars produce powerful radio jets, The
1:15:28
Speaker 1: distinction correlates with black hole spin and magnetic field configuration.
1:15:33
Speaker 1: Jets require strong magnetic fields threading the accretion disk and
1:15:38
Speaker 1: event horizon. As the black hole spins, it drags these
1:15:42
Speaker 1: fields around, extracting rotational energy and launching plasma along the
1:15:48
Speaker 1: spin axis at relativistic speeds. TON 618's jets punch through
1:15:55
Speaker 1: the accretion disk, and continue outward, eventually creating radio lobes
1:16:01
Speaker 1: millions of light years across. These lobes aren't visible in
1:16:05
Speaker 1: current observations due to TON618' s distance, but they must exist
1:16:11
Speaker 1: based on the radio spectrum. The jets deposit energy in
1:16:15
Speaker 1: the intergalactic medium, heating it and potentially triggering or suppressing
1:16:21
Speaker 1: star formation in smaller galaxies they encounter. jet speeds approach
1:16:27
Speaker 1: the speed of light, particles accelerated to such velocities produce
1:16:32
Speaker 1: synchrotron radiation, emission from charged particles spiraling in magnetic fields.
1:16:40
Speaker 1: This produces the radio signature we detect. The total power
1:16:45
Speaker 1: in the jets can be estimated from radio luminosity, typically
1:16:50
Speaker 1: a few percent of the quasar's total luminosity. For tonne 618,
1:16:57
Speaker 1: jet power might reach 10 to the power of 39
1:17:00
Speaker 1: watts or more, enough to power a trillion suns worth
1:17:04
Speaker 1: of energy output in mechanical form. The alignment between jets
1:17:08
Speaker 1: and the Lyman-alpha nebula structure suggests these outflows have been
1:17:13
Speaker 1: stable for millions of years. Jets can be intermittent, turning
1:17:18
Speaker 1: on and off as accretion rates vary. but producing the
1:17:23
Speaker 1: observed nebular structure requires sustained jet activity. The gas didn't
1:17:29
Speaker 1: just get blown away randomly, it was shaped and sculpted
1:17:33
Speaker 1: by persistent, directed outflows. This stability implies a stable accretion geometry.
1:17:41
Speaker 1: The accretion disk maintains its orientation over long periods. The
1:17:46
Speaker 1: black hole's spin axis stays aligned with the disk. Major
1:17:50
Speaker 1: disturbances like galaxy mergers or sudden gas infall from unusual directions,
1:17:57
Speaker 1: would disrupt this alignment and potentially shut down the jets temporarily.
1:18:03
Speaker 1: The fact that we see stable jets suggests TON 618
1:18:08
Speaker 1: has had a relatively undisturbed recent history, at least on
1:18:13
Speaker 1: timescales of millions of years. The nebula's mass, 100 billion
1:18:18
Speaker 1: solar masses totaled, exceeds the black hole's mass significantly. This
1:18:24
Speaker 1: gas represents the building material for future stars, or future
1:18:29
Speaker 1: black hole accretion. If conditions allow, the nebula could form
1:18:34
Speaker 1: thousands of massive star clusters over the next few billion years. Alternatively,
1:18:41
Speaker 1: if the quasar remains active, it might gradually consume much
1:18:46
Speaker 1: of this material. The fate depends on cooling times. Hot
1:18:53
Speaker 1: gas must cool before it can collapse and form stars.
1:18:58
Speaker 1: Cooling depends on density and temperature. In the inner regions
1:19:04
Speaker 1: where the quasar's radiation keeps the gas ionized and hot,
1:19:08
Speaker 1: cooling times exceed the age of the universe. This gas
1:19:13
Speaker 1: won't form stars anytime soon. In outer regions where radiation
1:19:18
Speaker 1: is weaker, cooling times shorten. Star formation might proceed there,
1:19:24
Speaker 1: building the stellar halo of the host galaxy. This process
1:19:29
Speaker 1: mirrors what we see in modern galaxies. Massive elliptical galaxies
1:19:34
Speaker 1: contain old stellar populations with little ongoing star formation. Their
1:19:39
Speaker 1: gas is hot and diffuse, kept that way by past
1:19:43
Speaker 1: quasar activity and ongoing heating from old stars. The quasar
1:19:48
Speaker 1: phase ended billions of years ago, but its effects persist.
1:19:53
Speaker 1: TON618 shows us this process in progress, the moment when
1:19:59
Speaker 1: a quasar is actively suppressing star formation through feedback. The
1:20:04
Speaker 1: Lyman-alpha emission itself provides a diagnostic tool This ultraviolet line
1:20:10
Speaker 1: occurs when electrons in hydrogen atoms transition from the first
1:20:15
Speaker 1: excited state to the ground state. The photon energy corresponds
1:20:20
Speaker 1: to 10.2 electron volts, placing it in the UV. TON618' s
1:20:27
Speaker 1: extreme luminosity produces copious UV radiation that ionizes the surrounding hydrogen.
1:20:35
Speaker 1: When electrons recombine, They cascade down through energy levels, producing
1:20:40
Speaker 1: Lyman-alpha photons. The nebula glows brightly in this line because
1:20:46
Speaker 1: the quasar provides the energy source. Turn off the quasar,
1:20:51
Speaker 1: and the nebula would fade on timescales of thousands to
1:20:54
Speaker 1: millions of years, the time needed for electrons to recombine
1:20:59
Speaker 1: and for Lyman-alpha photons to scatter out of the nebula.
1:21:04
Speaker 1: The current brightness tells us the quasar has been active recently,
1:21:09
Speaker 1: within the past few million years at most. Scattering matters here.
1:21:15
Speaker 1: Lyme and alpha photons don't escape directly. They scatter off
1:21:20
Speaker 1: neutral hydrogen many times before finally escaping. This resonant scattering
1:21:26
Speaker 1: can trap photons for extended periods, creating a diffuse glow
1:21:31
Speaker 1: around the source. The nebula's extended structure partially results from
1:21:37
Speaker 1: this scattering process. Photons produced near the quasar random walk
1:21:43
Speaker 1: outward through scattering, eventually emerging at large distances. The velocity
1:21:50
Speaker 1: structure of the nebula encodes its history. Different regions show
1:21:55
Speaker 1: different velocities relative to the quasar. Some gas moves toward us,
1:22:01
Speaker 1: some away. some orbits the black hole. By mapping these
1:22:06
Speaker 1: velocities using spectroscopy, astronomers reconstruct the three-dimensional structure and dynamics.
1:22:14
Speaker 1: The ALMA observations that revealed the molecular gas component provided
1:22:20
Speaker 1: precisely this information, velocity maps showing how gas flows through
1:22:25
Speaker 1: the system. These observations showed two distinct components, The inner
1:22:31
Speaker 1: molecular outflow moves at hundreds of kilometres per second, directly
1:22:36
Speaker 1: driven by the quasar's jets and radiation. The extensive circumgalactic
1:22:42
Speaker 1: medium moves more slowly, representing gas that's been affected by
1:22:47
Speaker 1: the quasar but not directly expelled. Both components contain molecular hydrogen, H2,
1:22:55
Speaker 1: rather than just atomic hydrogen. This indicates sufficient density and
1:23:00
Speaker 1: shielding for molecules to survive, despite the intense radiation environment.
1:23:06
Speaker 1: Molecular gas is star formation fuel. Under the right conditions,
1:23:11
Speaker 1: it collapses to form stars. The presence of 100 billion
1:23:15
Speaker 1: solar masses of molecular gas around ton 618 suggests enormous
1:23:21
Speaker 1: star formation potential. Yet current observations show the gas remains
1:23:27
Speaker 1: mostly diffuse, Why isn't it forming stars now? Turbulence provides
1:23:33
Speaker 1: one answer. Gas must be relatively calm to collapse under
1:23:37
Speaker 1: its own gravity. Turbulence, random motions on various scales, provides
1:23:43
Speaker 1: support against collapse, similar to thermal pressure. The jets and
1:23:48
Speaker 1: outflows from TON-618 inject turbulent energy, stirring the gas and
1:23:55
Speaker 1: preventing collapse. Only once the quasar shuts down and turbulence
1:24:00
Speaker 1: dissipates can star formation proceed efficiently. Temperature offers another factor.
1:24:07
Speaker 1: Molecular gas must cool to about 10 Kelvin to form stars.
1:24:12
Speaker 1: Warmer gas has too much thermal pressure. The quasar's radiation
1:24:17
Speaker 1: heats the gas directly through photoionization and indirectly through UV photons,
1:24:24
Speaker 1: that dissociate molecules and free atoms that then recombine, releasing heat.
1:24:31
Speaker 1: This heating maintains temperatures too high for star formation. Magnetic
1:24:37
Speaker 1: fields add additional complexity. Molecular gas contains embedded magnetic fields
1:24:44
Speaker 1: that provide extra support against gravitational collapse. Field strengths and
1:24:51
Speaker 1: geometries remain poorly constrained for TON618, but analogy with other
1:24:57
Speaker 1: systems suggests fields play a significant role. Turbulence can amplify
1:25:04
Speaker 1: fields through dynamo action. Strong fields resist compression, further suppressing
1:25:11
Speaker 1: star formation. All these factors combine to keep TON618' s nebula
1:25:17
Speaker 1: in a state of suspended potential, vast amounts of gas
1:25:21
Speaker 1: capable of forming stars, but prevented from doing so by
1:25:25
Speaker 1: the quasar's ongoing activity. This state won't last forever. Eventually,
1:25:31
Speaker 1: the gas supply runs low, accretion slows, the quasar dims,
1:25:39
Speaker 1: and conditions shift. Then the nebula can cool, fragment, and
1:25:45
Speaker 1: form the next generation of stars, that will comprise the
1:25:49
Speaker 1: mature galaxy. This suspended state represents a pivotal moment in
1:25:54
Speaker 1: cosmic history. We're witnessing the transition between violent quasar-driven activity
1:26:01
Speaker 1: and the mature galaxy that will emerge afterward. Other systems
1:26:05
Speaker 1: at lower redshifts show us snapshots of later stages in
1:26:10
Speaker 1: this process. Quasars dimming, gas cooling, star formation igniting. TON618
1:26:20
Speaker 1: catches the system at peak activity, maximum energy input, before
1:26:26
Speaker 1: the inevitable decline begins. How long does this phase last?
1:26:31
Speaker 1: Quasars don't shine forever. Their lifetimes depend on fuel supply
1:26:36
Speaker 1: and feeding efficiency. For systems like TON618, typical quasar lifetimes
1:26:43
Speaker 1: range from tens to hundreds of millions of years. brief
1:26:47
Speaker 1: by cosmic standards, but long enough to profoundly reshape their environments.
1:26:54
Speaker 1: The current bright phase might persist for another 50 million
1:26:58
Speaker 1: years before fuel depletion forces the black hole into dormancy.
1:27:03
Speaker 1: What signals the transition from active to dormant? The accretion
1:27:08
Speaker 1: rate provides the key metric. As long as sufficient gas
1:27:12
Speaker 1: reaches the black hole, the quasar continues shining. Once the
1:27:17
Speaker 1: supply diminishes, whether through consumption, expulsion, or changes in the
1:27:23
Speaker 1: galactic environment, the accretion rate drops, the disk cools, the
1:27:30
Speaker 1: jets weaken, the radiation field dims. This happens gradually over
1:27:36
Speaker 1: millions of years, not suddenly. During this transition, the nebula's
1:27:42
Speaker 1: fate becomes sealed. Without the quasar's energy input, Turbulence dissipates.
1:27:48
Speaker 1: Heating stops. Magnetic fields decay. The gas begins cooling through radiation,
1:27:55
Speaker 1: losing energy to space. Molecular hydrogen excels at cooling. Its
1:28:00
Speaker 1: rotation and vibration states efficiently radiate away thermal energy. Over
1:28:07
Speaker 1: several tens of millions of years, temperatures drop from hundreds
1:28:11
Speaker 1: of Kelvin to the critical 10 Kelvin threshold. where gravitational
1:28:17
Speaker 1: collapse becomes inevitable. Once cooling proceeds sufficiently, fragmentation begins. The
1:28:24
Speaker 1: once-uniform nebula breaks into clumps. Each clump contracts under its
1:28:29
Speaker 1: own gravity. As contraction continues, densities rise, triggering further collapse. Eventually,
1:28:37
Speaker 1: these fragments become dense enough and hot enough at their
1:28:41
Speaker 1: cause to ignite nuclear fusion. Stars are born. The process
1:28:46
Speaker 1: transforms the diffuse nebula into a stellar population, converting 100
1:28:52
Speaker 1: billion solar masses of gas into perhaps 10 to 20
1:28:56
Speaker 1: billion stars. This star formation won't happen uniformly throughout the nebula.
1:29:04
Speaker 1: Different regions will form stars at different times and rates.
1:29:09
Speaker 1: The densest regions collapse first. The most turbulent regions resist
1:29:14
Speaker 1: collapse longest. Regions with stronger magnetic fields form stars more slowly.
1:29:21
Speaker 1: The result is a complex, extended period of star formation
1:29:26
Speaker 1: lasting hundreds of millions of years. What kind of galaxy
1:29:31
Speaker 1: emerges from this process? The answer depends on many factors.
1:29:36
Speaker 1: The nebula's angular momentum, its density distribution, the history of
1:29:41
Speaker 1: mergers with other galaxies. The massive black hole at the
1:29:45
Speaker 1: center suggests a massive elliptical galaxy forms eventually. Ellipticals contain
1:29:52
Speaker 1: old stellar populations, little gas, and limited ongoing star formation.
1:30:00
Speaker 1: consumed or expelled most of its gas during an earlier
1:30:04
Speaker 1: active phase. The host galaxy likely already contains some older
1:30:09
Speaker 1: stars formed before TON618 became a quasar. These stars are
1:30:16
Speaker 1: invisible to us now, outshone by the quasar's brilliance. But
1:30:21
Speaker 1: they exist, orbiting the black hole, contributing to the galaxy's
1:30:25
Speaker 1: total mass. The nebula will add to this existing population,
1:30:31
Speaker 1: creating multiple generations of stars with different ages and compositions.
1:30:36
Speaker 1: Can we see examples of this process at later stages? Yes.
1:30:41
Speaker 1: Astronomers study post-starburst galaxies, systems that recently ceased forming stars
1:30:48
Speaker 1: after an intense burst. These objects show strong absorption lines
1:30:53
Speaker 1: from massive stars that formed within the past billion years,
1:30:57
Speaker 1: but lack the emission lines indicating ongoing star formation. They
1:31:03
Speaker 1: represent what TON 618's host might look like a few
1:31:08
Speaker 1: billion years from now. We also study massive elliptical galaxies
1:31:14
Speaker 1: in the nearby universe, the descendants of systems like TON 618.
1:31:21
Speaker 1: These contain ancient stellar populations, dormant supermassive black holes, and
1:31:27
Speaker 1: little gas. Their stars orbit in random directions rather than
1:31:32
Speaker 1: in organised disks, suggesting formation through violent processes involving mergers
1:31:38
Speaker 1: and feedback. The Milky Way's neighbour M87 provides an example.
1:31:45
Speaker 1: A massive elliptical with a 5.4 billion solar mass black
1:31:50
Speaker 1: hole now quiet after its quasiphase ended long ago. TON
1:31:55
Speaker 1: 618's nebula encodes the galaxy's future in its present structure.
1:32:01
Speaker 1: The total gas mass determines the final stellar mass. The
1:32:06
Speaker 1: velocity structure determines the galaxy's rotation. The density distribution determines
1:32:13
Speaker 1: where stars form. Reading this information requires detailed observations that
1:32:19
Speaker 1: push current instruments to their limits. The alignment between the
1:32:24
Speaker 1: nebula and the radio jets reveals something crucial about the
1:32:29
Speaker 1: system's geometry. Jets emerge perpendicular to the accretion disk, following
1:32:36
Speaker 1: the black hole's spin axis. The fact that the molecular
1:32:41
Speaker 1: outflow and circumgalactic medium both align with this axis indicates
1:32:46
Speaker 1: the jets have shaped the gas distribution on scales from
1:32:50
Speaker 1: thousands to hundreds of thousands of light years. This shaping
1:32:56
Speaker 1: happens through momentum transfer. Jets carry enormous kinetic energy. When
1:33:02
Speaker 1: they collide with surrounding gas, they transfer momentum, pushing gas
1:33:07
Speaker 1: outward and sideways. The collision creates shocks, abrupt increases in
1:33:13
Speaker 1: pressure and temperature, that heat and compress the gas. These
1:33:18
Speaker 1: shocks drive the molecular outflow, launching gas at hundreds of
1:33:24
Speaker 1: kilometers per second away from the galaxy's center. But jets
1:33:28
Speaker 1: do more than push gas around. They also inject energy
1:33:32
Speaker 1: throughout the nebula. High-energy particles streaming along the jets interact
1:33:38
Speaker 1: with surrounding matter through collisions and electromagnetic interactions. This heats
1:33:45
Speaker 1: the gas and generates radiation across the spectrum. The process,
1:33:51
Speaker 1: called jet-driven heating, helps maintain the nebula's elevated temperature and
1:33:57
Speaker 1: prevents premature star formation. Magnetic fields play a critical but
1:34:03
Speaker 1: poorly understood role. The jets themselves contain strong magnetic fields.
1:34:10
Speaker 1: Field lines wound up by the rotating accretion disk and
1:34:14
Speaker 1: carried outward by flowing plasma. These fields extend into the nebula,
1:34:20
Speaker 1: threading through the gas. Field pressure provides additional support against
1:34:26
Speaker 1: gravitational collapse. Field tension can accelerate gas perpendicular to field lines.
1:34:33
Speaker 1: Understanding the magnetic field structure remains a major observational challenge.
1:34:39
Speaker 1: Different regions of the nebula likely have different magnetic field
1:34:43
Speaker 1: strengths and geometries. Near the jets, fields are strong and well-organised,
1:34:50
Speaker 1: aligned with the jet direction. Farther out, fields weaken and
1:34:55
Speaker 1: become more tangled due to turbulence. In the densest clumps,
1:35:00
Speaker 1: fields may be compressed and amplified. This complexity makes modelling
1:35:05
Speaker 1: the system extremely difficult. The circumgalactic medium represents the nebula's
1:35:12
Speaker 1: outer envelope, gas extending to hundreds of kiloparsecs, but not
1:35:17
Speaker 1: directly expelled by jets or winds. This gas has a
1:35:22
Speaker 1: different origin than the inner outflow. It might be primordial
1:35:26
Speaker 1: material that never fell into the galaxy. It might be
1:35:30
Speaker 1: gas expelled by earlier feedback episodes. It might be material
1:35:36
Speaker 1: tidally stripped from smaller galaxies, merging with the host. Its
1:35:41
Speaker 1: presence indicates a complex history of gas flows into and
1:35:45
Speaker 1: out of the galaxy. This outer gas reservoir serves another
1:35:50
Speaker 1: function beyond future star formation. It regulates the system's evolution.
1:35:57
Speaker 1: As the quasar expels gas from the inner regions, this
1:36:01
Speaker 1: outer reservoir can flow back inward, potentially reigniting accretion and
1:36:07
Speaker 1: restarting the quasar. This creates a feedback cycle where active
1:36:12
Speaker 1: and dormant phases alternate over hundreds of millions of years.
1:36:17
Speaker 1: Whether TON 618 has experienced previous cycles remains unknown. The
1:36:23
Speaker 1: mass budget provides important constraints. The black hole contains 40
1:36:29
Speaker 1: to 66 billion solar masses, depending on the measurement. The
1:36:35
Speaker 1: nebula contains 100 billion solar masses of gas. The existing
1:36:41
Speaker 1: stellar population likely contains several hundred billion solar masses, though
1:36:47
Speaker 1: we can't observe it directly. The total baryonic mass in
1:36:51
Speaker 1: the system exceeds 500 billion solar masses, comparable to the
1:36:56
Speaker 1: most massive galaxies in today's universe. Dark matter dominates the
1:37:02
Speaker 1: total mass. The galaxy sits within a dark matter halo
1:37:07
Speaker 1: containing perhaps several trillion solar masses. This dark matter provides
1:37:13
Speaker 1: the gravitational potential well that holds the system together. Without it,
1:37:19
Speaker 1: The violent feedback from the quasar would have dispersed the
1:37:23
Speaker 1: nebula entirely. Dark matter's gravity keeps everything bound, despite the
1:37:30
Speaker 1: intense radiation pressure. The interplay between baryonic matter and dark
1:37:35
Speaker 1: matter shapes the galaxy's structure. Baryons cool and concentrate toward
1:37:41
Speaker 1: the centre, where they form stars and feed the black hole.
1:37:45
Speaker 1: Dark matter remains distributed more broadly in a roughly spherical halo.
1:37:51
Speaker 1: The ratio between baryonic and dark matter mass in the
1:37:54
Speaker 1: central regions exceeds the cosmic average because baryons have concentrated
1:37:59
Speaker 1: through dissipative processes while dark matter cannot. Chemical composition adds
1:38:06
Speaker 1: another layer of complexity. The gas in Ton, 618's nebula,
1:38:13
Speaker 1: isn't pure hydrogen and helium. It contains metals, elements heavier
1:38:18
Speaker 1: than helium produced by stellar nucleosynthesis. These metals, though comprising
1:38:24
Speaker 1: only a small fraction by mass, profoundly affect the gases' behaviour.
1:38:30
Speaker 1: They enhance cooling through emission lines. They provide opacity, affecting
1:38:36
Speaker 1: radiation transfer. They eventually become incorporated into planets and life.
1:38:44
Speaker 1: Where do these metals come from? Stars that formed earlier
1:38:48
Speaker 1: in the host galaxies or in smaller galaxies that merged
1:38:52
Speaker 1: with it. These stars lived their lives, fused lighter elements
1:38:57
Speaker 1: into heavier ones, and expelled material through stellar winds or
1:39:02
Speaker 1: supernova explosions. That enriched material mixed with primordial gas, raising
1:39:09
Speaker 1: the metallicity. The current metallicity in TON 618's nebula likely
1:39:14
Speaker 1: reaches 20-50% of the solar value. Not pristine, but not
1:39:21
Speaker 1: fully enriched either. This intermediate metallicity tells us about the
1:39:27
Speaker 1: galaxy's history. It formed stars before becoming a quasar. Those
1:39:32
Speaker 1: stars produce the metals we now observe. But the majority
1:39:37
Speaker 1: of star formation hasn't happened yet. That awaits the nebula's
1:39:42
Speaker 1: collapse after the quasar shuts down. The final stellar population
1:39:48
Speaker 1: will have higher metallicity than the current nebula because ongoing
1:39:53
Speaker 1: star formation will continue enriching the gas. Or, the spatial
1:39:58
Speaker 1: distribution of metals within the nebula likely isn't uniform. Regions
1:40:04
Speaker 1: closer to the black hole experienced more intense radiation and heating,
1:40:09
Speaker 1: possibly affecting chemical processes. Regions where jets interact with gas
1:40:15
Speaker 1: might show different compositions, due to shock chemistry. Mapping metallicity
1:40:22
Speaker 1: variations requires spectroscopic observations at multiple positions, observations that challenge
1:40:29
Speaker 1: current instrumental capabilities. Dust adds further complications. A small fraction
1:40:36
Speaker 1: of metals condenses into solid grains, dust particles typically smaller
1:40:41
Speaker 1: than a micron. These grains affect radiation transfer by absorbing
1:40:47
Speaker 1: and scattering light. They also catalyze molecule formation by providing
1:40:52
Speaker 1: surfaces where atoms can meet and bond. The amount and
1:40:57
Speaker 1: distribution of dust in TON 618's nebula remain poorly constrained,
1:41:04
Speaker 1: but certainly affect the system's evolution. Observing dust directly requires
1:41:10
Speaker 1: infrared observations. Dust absorbs ultraviolet and optical light from the quasar,
1:41:16
Speaker 1: heats up, and re-radiates in the infrared. The resulting infrared
1:41:21
Speaker 1: emission provides information about dust mass, temperature, and distribution. For TON618,
1:41:30
Speaker 1: such observations require space-based infrared telescopes. Ground-based instruments can't access
1:41:38
Speaker 1: the relevant wavelengths due to atmospheric absorption. Future observations will
1:41:44
Speaker 1: revolutionise our understanding. The James Webb Space Telescope's infrared capabilities
1:41:51
Speaker 1: can probe the dusty regions around TON618. The Extremely Large Telescope,
1:41:59
Speaker 1: once operational, will provide unprecedented spatial resolution in optical and
1:42:05
Speaker 1: infrared light. Next-generation radio arrays will map molecular gas with
1:42:11
Speaker 1: exquisite detail. These facilities will transform TON618 from a distant
1:42:18
Speaker 1: curiosity into a detailed laboratory for studying galaxy evolution. What
1:42:24
Speaker 1: questions remain unanswered? Many. We don't know the precise three-dimensional
1:42:30
Speaker 1: geometry of the nebula. Current observations provide projections on the sky,
1:42:36
Speaker 1: but not depth information. We don't know the detailed velocity
1:42:41
Speaker 1: field throughout the entire structure. We don't know how magnetic
1:42:45
Speaker 1: fields vary spatially. We don't know the metallicity distribution. We
1:42:51
Speaker 1: don't know the dust content. We don't know whether the
1:42:54
Speaker 1: host galaxy has experienced previous active phases. Answering these questions
1:43:01
Speaker 1: requires coordinated observing campaigns using multiple telescopes across the electromagnetic spectrum.
1:43:09
Speaker 1: Radio observations map molecular gas. Infrared observations probe dust and
1:43:15
Speaker 1: obscured star formation. Optical observations trace ionized gas. X-ray observations
1:43:23
Speaker 1: reveal the hottest material near the black hole. Each wavelength
1:43:28
Speaker 1: provides complementary information about different components and processes. The challenge
1:43:34
Speaker 1: lies in combining these diverse observations into a coherent physical model.
1:43:40
Speaker 1: Different observations sample different physical conditions, temperatures, densities, ionization states.
1:43:49
Speaker 1: Connecting them requires detailed modelling of radiative transfer, chemistry and dynamics.
1:43:57
Speaker 1: Computational simulations help by predicting what observations should show for
1:44:03
Speaker 1: different model parameters, allowing comparison between theory and observation. TON618
1:44:11
Speaker 1: represents more than an individual object. It's a window into
1:44:16
Speaker 1: cosmic dawn. showing us galaxy formation in action. By studying
1:44:22
Speaker 1: it and similar systems at high redshift, we reconstruct the
1:44:26
Speaker 1: processes that built today's galaxies. We learn how black holes
1:44:31
Speaker 1: and galaxies co-evolve. We understand how feedback regulates star formation.
1:44:38
Speaker 1: We trace the chemical enrichment of the universe. Each distant
1:44:42
Speaker 1: quasar adds another piece to this cosmic puzzle. The broader
1:44:47
Speaker 1: implications extend beyond individual systems. Ton, 618's existence, constrains theoretical
1:44:55
Speaker 1: models of the early universe. How common were such massive
1:44:59
Speaker 1: black holes? Current surveys suggest ultra-massive black holes are rare
1:45:05
Speaker 1: but not unique. Several candidates exist with comparable masses. Their
1:45:11
Speaker 1: scarcity indicates special conditions were needed for their formation. Perhaps
1:45:17
Speaker 1: they required unusually dense environments where gas could collapse rapidly.
1:45:22
Speaker 1: Perhaps they formed from direct collapse scenarios rather than stellar remnants.
1:45:29
Speaker 1: Perhaps they grew through exceptionally efficient accretion or rapid merger sequences.
1:45:35
Speaker 1: Population studies matter here. By cataloguing all known ultramassive black
1:45:41
Speaker 1: holes and analysing their properties statistically, astronomers can infer the
1:45:47
Speaker 1: conditions that produce them. Do they preferentially appear in certain
1:45:52
Speaker 1: cosmic environments? Do they show correlations with particular galaxy types?
1:46:00
Speaker 1: Do their host galaxies share common characteristics? These questions guide
1:46:07
Speaker 1: searches for additional examples and inform simulations of early structure formation.
1:46:13
Speaker 1: The theoretical framework faces genuine challenges. Standard accretion models predict
1:46:19
Speaker 1: growth timescales. A stellar mass black hole of 10 solar
1:46:25
Speaker 1: masses accreting at the Eddington limit would require hundreds of
1:46:29
Speaker 1: millions of years to reach a million solar masses. Reaching
1:46:34
Speaker 1: 40 billion solar masses within 3 billion years, the time
1:46:39
Speaker 1: available given ton 618's redshift, pushes these models to their limits.
1:46:46
Speaker 1: Super-Eddington accretion provides one solution. If black holes temporarily exceeded
1:46:52
Speaker 1: the Eddington limit during particularly gas-rich phases, they could grow
1:46:57
Speaker 1: faster than conventional models allow. Another possibility involves massive seed
1:47:03
Speaker 1: black holes. Instead of starting from stellar remnants of tens
1:47:08
Speaker 1: of solar masses, Perhaps some black holes began with thousands
1:47:13
Speaker 1: or even millions of solar masses. Direct collapse scenarios propose
1:47:19
Speaker 1: that under certain conditions, massive gas clouds could collapse directly
1:47:25
Speaker 1: into black holes without forming stars first. These scenarios require
1:47:31
Speaker 1: specific circumstances, pristine gas lacking metals that would enable cooling
1:47:37
Speaker 1: and fragmentation. Intense radiation fields preventing normal star formation. Rapid
1:47:43
Speaker 1: infall preventing feedback from disrupting the collapse. Whether such conditions
1:47:49
Speaker 1: existed in the early universe remains debated. Merger-driven growth offers
1:47:54
Speaker 1: yet another pathway. If multiple smaller black holes merged repeatedly
1:48:00
Speaker 1: in dense galactic environments, the combined mass could grow rapidly.
1:48:06
Speaker 1: Each merger would release gravitational waves and potentially kick the
1:48:11
Speaker 1: remnant black hole through recoil. But in sufficiently massive dark
1:48:16
Speaker 1: matter halos, the black hole would remain gravitational. bound and
1:48:21
Speaker 1: continue growing through subsequent mergers and accretion. Numerical simulations explore
1:48:28
Speaker 1: these scenarios, calculating expected growth rates and comparing them to observations.
1:48:35
Speaker 1: The physics near Ton 618's event horizon defies everyday intuition.
1:48:42
Speaker 1: At 1,300 astronomical units, the Schwarzschild radius exceeds the size
1:48:48
Speaker 1: of our entire solar system 40 times over. Light itself
1:48:53
Speaker 1: would take weeks to cross from one side to the other.
1:48:56
Speaker 1: A beam of light traveling at 300,000 kilometers per second
1:49:01
Speaker 1: traversing a distance so vast that our planetary system becomes
1:49:06
Speaker 1: insignificant by comparison. Matter approaching this boundary experiences gravitational forces
1:49:15
Speaker 1: strong enough to tear apart stars long before crossing the
1:49:20
Speaker 1: event horizon. Tidal forces scale inversely with black hole mass
1:49:25
Speaker 1: for equal distances from the centre. Paradoxically, This means crossing
1:49:30
Speaker 1: the event horizon of an ultra-massive black hole, like TON618,
1:49:36
Speaker 1: would be less violent than crossing into a stellar-mass black hole.
1:49:41
Speaker 1: The tidal gradient, the difference in gravitational force across an
1:49:45
Speaker 1: object's extent, decreases for larger black holes. An astronaut falling
1:49:51
Speaker 1: into TON618 could theoretically cross the event horizon without immediate spaghettification.
1:49:58
Speaker 1: The fatal tidal forces would manifest closer to the singularity,
1:50:03
Speaker 1: deep within the event horizon's interior. This counterintuitive result highlights
1:50:09
Speaker 1: general relativity's subtleties. The event horizon isn't a physical surface.
1:50:15
Speaker 1: Nothing marks its location locally. An infalling observer would notice
1:50:20
Speaker 1: nothing special upon crossing. No wall, no barrier, no sudden change.
1:50:27
Speaker 1: Only later, attempting to escape, would they discover the impossibility
1:50:32
Speaker 1: of their situation? All future-directed paths lead inward. No amount
1:50:40
Speaker 1: of thrust could reverse course. The event horizon represents a
1:50:45
Speaker 1: one-way membrane in spacetime itself. Hawking radiation introduces quantum effects
1:50:53
Speaker 1: Even black holes emit thermal radiation due to quantum fluctuations
1:50:57
Speaker 1: near the event horizon. The temperature depends inversely on mass.
1:51:03
Speaker 1: Stellar mass black holes have temperatures of millionths of a Kelvin.
1:51:09
Speaker 1: Ton 618's temperature would be proportionally lower, trillionths of a Kelvin,
1:51:15
Speaker 1: far colder than the cosmic microwave background. Such black holes
1:51:20
Speaker 1: gain mass from background radiations Faster than they lose mass
1:51:24
Speaker 1: to Hawking radiation, they grow rather than evaporate. Only in
1:51:31
Speaker 1: the distant future, after stars cease forming and the universe
1:51:35
Speaker 1: cools below even the minuscule Hawking temperature, would ultra-massive black
1:51:41
Speaker 1: holes begin evaporating. The timescale for complete evaporation scales is
1:51:47
Speaker 1: the cube of the mass. For ton 618, This exceeds
1:51:53
Speaker 1: 10 to the 100th power years, a number so large
1:51:58
Speaker 1: it dwarfs the current age of the universe by unimaginable factors.
1:52:03
Speaker 1: The black hole would outlast not just stars, but the
1:52:07
Speaker 1: very concept of conventional time in any recognisable sense. The
1:52:12
Speaker 1: information paradox lurks here. What happens to information that falls
1:52:18
Speaker 1: into a black hole? Does it disappear? violating quantum mechanics'
1:52:23
Speaker 1: unitarity principle? Does it somehow escape through Hawking radiation? Does
1:52:29
Speaker 1: it remain encoded on the event horizon? These questions remain
1:52:35
Speaker 1: unresolved despite decades of theoretical work. TON618, like all black holes,
1:52:44
Speaker 1: embodies this fundamental tension between general relativity and quantum mechanics.
1:52:51
Speaker 1: String theory and other quantum gravity approaches propose solutions. Perhaps
1:52:57
Speaker 1: black holes aren't truly black, but rather fuzzballs, quantum objects
1:53:02
Speaker 1: without event horizons. Perhaps the interior connects to other universes
1:53:08
Speaker 1: through wormhole-like structures. Perhaps information is preserved through holographic principles
1:53:15
Speaker 1: where the event horizon's surface encodes the volume's information. None
1:53:20
Speaker 1: of these ideas have achieved consensus, and experimental tests remain
1:53:25
Speaker 1: far beyond current capabilities. Gravitational waves from TON 618's formation
1:53:32
Speaker 1: and growth might carry information. When black holes merge, they
1:53:37
Speaker 1: produce gravitational waves, ripples in spacetime itself propagating at light speed.
1:53:44
Speaker 1: Detectors like LIGO and Virgo observe mergers of stellar mass
1:53:49
Speaker 1: black holes. Future space-based detectors like LISA will access lower
1:53:55
Speaker 1: frequencies corresponding to supermassive black hole mergers. Detecting gravitational waves
1:54:03
Speaker 1: from ultramassive black hole mergers would require even more ambitious instruments,
1:54:09
Speaker 1: but the scientific payoff would be enormous. Such detections would
1:54:14
Speaker 1: reveal black hole spins, masses, and orbital parameters with precision
1:54:19
Speaker 1: impossible through electromagnetic observations. They would test general relativity in
1:54:26
Speaker 1: the strongfield regime, where spacetime curvature reaches extreme values. They
1:54:32
Speaker 1: would provide independent mass measurements to compare with spectroscopic estimates.
1:54:39
Speaker 1: They would probe the merger history of massive galaxies across
1:54:44
Speaker 1: cosmic time. The challenge lies in the timescales. Gravitational wave
1:54:50
Speaker 1: signals from ultra-massive black holes have periods of days to years.
1:54:56
Speaker 1: Detecting them requires continuous monitoring over extended periods, correlating data
1:55:02
Speaker 1: from multiple spacecraft to achieve sufficient sensitivity. The signals would
1:55:09
Speaker 1: be weak. Even the most massive mergers produce only tiny
1:55:13
Speaker 1: strains in spacetime. by the time waves reach us. But
1:55:17
Speaker 1: the scientific returns justify the technological investment. TON-6, 1-8 jets,
1:55:25
Speaker 1: deserve closer examination. Radio observations reveal powerful outflows carrying enormous
1:55:32
Speaker 1: energy into the surrounding medium. The jet launching mechanism involves
1:55:37
Speaker 1: complex magnetohydrodynamics near the event horizon. Magnetic fields threading the
1:55:44
Speaker 1: accretion disk become twisted and amplified by differential rotation. The
1:55:50
Speaker 1: fields extract rotational energy from the black hole itself through
1:55:55
Speaker 1: the Blandford-Znajek process, channeling it into collimated outflows travelling at
1:56:01
Speaker 1: near-light speeds. These relativistic jets interact with ambient gas, creating
1:56:08
Speaker 1: shock waves and turbulence. They inflate enormous radio-emitting bubbles visible
1:56:14
Speaker 1: in low-frequency observations. They deposit energy across vast regions, heating
1:56:21
Speaker 1: gas and preventing it from cooling and forming stars. This
1:56:25
Speaker 1: feedback mechanism helps explain why the most massive galaxies today
1:56:30
Speaker 1: contain relatively little cold gas, despite their enormous masses. Their
1:56:35
Speaker 1: central black holes expelled or heated the gas during previous
1:56:39
Speaker 1: active phases. For TON 618, the jets align with the
1:56:46
Speaker 1: Lyman-alpha nebula's major axis. This alignment isn't coincidental. The jets
1:56:54
Speaker 1: shape gas distribution by pushing material perpendicular to their propagation direction.
1:57:01
Speaker 1: Gas swept into the jet's path gets accelerated, heated, or dispersed.
1:57:08
Speaker 1: Gas lying perpendicular to the jet's experiences less direct interaction,
1:57:13
Speaker 1: allowing it to accumulate into the observed nebular structures. The
1:57:18
Speaker 1: jet power must be substantial, perhaps 10 to the power
1:57:22
Speaker 1: of 46 ergs per second, equivalent to the luminosity of
1:57:27
Speaker 1: a trillion suns. Magnetic fields throughout the system remain poorly constrained.
1:57:33
Speaker 1: Theory predicts strong fields near the black hole where they
1:57:37
Speaker 1: drive jets Fields in the accretion disk channel plasma and
1:57:42
Speaker 1: affect angular momentum transport. Fields in the nebula might influence
1:57:48
Speaker 1: gas dynamics and star formation. But observing these fields directly
1:57:54
Speaker 1: proves difficult. Polarization measurements provide indirect evidence, showing that radiation
1:58:01
Speaker 1: has interacted with magnetic fields. Future radio polarimetry could map
1:58:08
Speaker 1: field structures in detail. The host galaxy's stellar population remains
1:58:13
Speaker 1: essentially invisible, overwhelmed by the quasar's brilliance. Estimates suggest it
1:58:20
Speaker 1: likely contains hundreds of billions of stars based on the
1:58:24
Speaker 1: black hole galaxy mass relationship observed in nearby systems. This relationship,
1:58:32
Speaker 1: the M-sigma relation, correlates black hole mass with the velocity
1:58:37
Speaker 1: dispersion of stars in the galactic bulge. Extrapolating to TON618
1:58:46
Speaker 1: suggests a galaxy mass exceeding a trillion solar masses. Such
1:58:51
Speaker 1: a galaxy would rank among the most massive ever formed.
1:58:56
Speaker 1: Its dark matter halo would be correspondingly enormous. perhaps containing
1:59:01
Speaker 1: 10 trillion solar masses or more. The halo provides the
1:59:05
Speaker 1: gravitational well within which gas accumulates. Galaxies merge and structure grows.
1:59:13
Speaker 1: Understanding the halo's properties requires gravitational lensing observations. If a
1:59:19
Speaker 1: background galaxy fortuitously aligns with TON 618, its light would
1:59:25
Speaker 1: be bent and magnified. revealing the foreground mass distribution. Such
1:59:31
Speaker 1: alignments are rare, but not impossible. The cosmic web context matters.
1:59:38
Speaker 1: Large-scale structure simulations show that the most massive halos form
1:59:43
Speaker 1: at the intersections of filaments, the nodes where cosmic structure
1:59:48
Speaker 1: is densest. TON618 likely occupies such a node, positioned where
1:59:55
Speaker 1: multiple filaments meet. Gas flowing along filaments converges at these locations,
2:00:03
Speaker 1: providing abundant fuel for black hole growth and star formation.
2:00:08
Speaker 1: The system's environment probably included numerous companion galaxies, some of
2:00:13
Speaker 1: which may have merged with the host over time. Simulations
2:00:18
Speaker 1: help interpret observations by predicting what structures should look like
2:00:22
Speaker 1: under different assumptions. Cosmological simulations follow the evolution of dark
2:00:28
Speaker 1: matter from early density fluctuations to present-day structures. Adding gas physics,
2:00:36
Speaker 1: star formation, and black hole feedback allows comparison with observed galaxies.
2:00:43
Speaker 1: The simulations that best match observations constrain physical processes and
2:00:49
Speaker 1: parameter values, refining our understanding of how galaxies form. TON-618
2:00:56
Speaker 1: provides a particularly stringent test. Its extreme properties, ultra-massive black hole,
2:01:04
Speaker 1: enormous nebula, powerful jets, must all emerge naturally from physical
2:01:09
Speaker 1: processes operating in the early universe. Simulations that produce TON-618-like
2:01:17
Speaker 1: systems reveal which conditions and mechanisms were necessary. They guide
2:01:23
Speaker 1: observers toward key measurements that would distinguish between competing models.
2:01:28
Speaker 1: They suggest what future telescopes should look for when studying
2:01:32
Speaker 1: similar high redshift quasars. Future telescopes will transform our understanding.
2:01:39
Speaker 1: The James Webb Space Telescope, already operational, can detect infrared
2:01:45
Speaker 1: light from TON 618's host galaxy. piercing through dust that
2:01:51
Speaker 1: obscures optical observations. Webb's sensitivity allows imaging of structures near
2:01:56
Speaker 1: the quasar that were previously invisible, potentially revealing star formation regions,
2:02:03
Speaker 1: galactic morphology, and companion objects. The extremely large telescope, scheduled
2:02:11
Speaker 1: for completion in the late 2020s, will provide unprecedented angular
2:02:17
Speaker 1: resolution from the ground. Its 39-metre mirror will resolve features
2:02:23
Speaker 1: ten times smaller than current telescopes can achieve, possibly distinguishing
2:02:29
Speaker 1: different regions within TON618' s accretion disk or detecting individual star
2:02:36
Speaker 1: clusters in the host galaxy. Square-kilometre array radio observations will
2:02:43
Speaker 1: map the jets and magnetic fields with exquisite detail. This
2:02:48
Speaker 1: instrument's collecting area, equivalent to a square kilometer of radio antennas,
2:02:55
Speaker 1: will detect faint emissions from outflows and trace gas dynamics
2:03:00
Speaker 1: throughout the system. Combined with ALMA's molecular line observations, SKA
2:03:06
Speaker 1: data will reveal how jets shape the circumgalactic medium and
2:03:11
Speaker 1: regulate star formation across hundreds of thousands of light years.
2:03:17
Speaker 1: X-ray observatories like Athena, planned for the 2030s, will probe
2:03:22
Speaker 1: the high-energy physics near TON618' s event horizon. X-rays trace the
2:03:29
Speaker 1: hottest gas in the accretion disk's inner regions, where temperatures
2:03:34
Speaker 1: reach millions of degrees. Spectroscopy of these X-rays reveals chemical abundances,
2:03:41
Speaker 1: ionization states, and velocities. constraining accretion physics and testing general
2:03:47
Speaker 1: relativity in extreme gravitational fields. Time-resolved X-ray observations could detect
2:03:54
Speaker 1: variability caused by orbiting hotspots or magnetic reconnection events. Gravitational
2:04:02
Speaker 1: wave detectors might eventually sense TON618' s influence. Current detectors like
2:04:09
Speaker 1: LIGO and Virgo aren't sensitive enough to detect gravitational waves
2:04:15
Speaker 1: from individual supermassive black holes, but future space-based detectors, concepts
2:04:21
Speaker 1: like LISA, will observe lower frequency waves produced by merging
2:04:26
Speaker 1: supermassive black holes. If TON 618's black hole formed through mergers,
2:04:34
Speaker 1: as some theories suggest, similar events occurring today would generate
2:04:39
Speaker 1: detectable signals. These observations would reveal black hole spins, masses,
2:04:45
Speaker 1: and merger histories directly. Multimessenger astronomy combines electromagnetic observations with
2:04:52
Speaker 1: gravitational waves and neutrinos. If TON618' s jets accelerate particles to
2:05:00
Speaker 1: ultra-high energies, neutrino detectors might register signals from nuclear interactions
2:05:06
Speaker 1: in the jet plasma. Neutrinos travel unimpeded through space, arriving
2:05:12
Speaker 1: simultaneously with photons from the same event despite traversing different paths.
2:05:19
Speaker 1: Detecting neutrinos from TON618 would confirm hadronic acceleration mechanisms and
2:05:27
Speaker 1: constrain jet composition. Statistical studies of similar objects provide context.
2:05:35
Speaker 1: TON618 isn't unique. It's the most massive example of a population.
2:05:42
Speaker 1: Surveys identifying hundreds of high redshift quasars enable statistical analyses
2:05:47
Speaker 1: of their properties, clustering, and evolution. The distribution of black
2:05:52
Speaker 1: hole masses, accretion rates, and host galaxy properties reveals patterns
2:05:58
Speaker 1: that individual objects can't show. Comparing TON 618 to its
2:06:05
Speaker 1: peers highlights what makes it exceptional and what characteristics are
2:06:10
Speaker 1: typical for ultramassive systems. Quasar luminosity functions track the number
2:06:17
Speaker 1: density of quasars at different luminosities and redshifts. These functions
2:06:23
Speaker 1: show that luminous quasars were more common in the early universe,
2:06:27
Speaker 1: peaking around redshift 2-3 when the universe was 2-3 billion
2:06:31
Speaker 1: years old. TON618 at redshift 2.2 formed during this peak epoch.
2:06:42
Speaker 1: The decline in quasar activity at later times suggests that
2:06:46
Speaker 1: black hole growth rates decreased as gas supplies dwindled and
2:06:51
Speaker 1: feedback mechanisms became more effective at regulating accretion. Clustering analyses
2:06:57
Speaker 1: measure how quasars are distributed in space relative to the
2:07:01
Speaker 1: large-scale structure Quasars occupy the most massive dark matter halos,
2:07:08
Speaker 1: clustered in over-dense regions where galaxy formation is most active.
2:07:13
Speaker 1: TON 618's position within the cosmic web determines its environment
2:07:20
Speaker 1: and influences its evolution. If located at a filament intersection,
2:07:25
Speaker 1: it would have access to copious gas supplies flowing along
2:07:28
Speaker 1: multiple filaments. If isolated in a massive halo, its fuel
2:07:34
Speaker 1: supply would depend more on internal processes like galaxy mergers.
2:07:40
Speaker 1: Chemical evolution studies trace element abundances through cosmic history. Early
2:07:46
Speaker 1: generation stars produced light elements, carbon, oxygen, nitrogen. Later generations
2:07:53
Speaker 1: synthesized heavier elements, iron, silicon, magnesium. The spectrum of TOS
2:08:01
Speaker 1: broadline region shows strong emission lines from carbon, nitrogen, and oxygen,
2:08:07
Speaker 1: indicating that significant stellar nucleosynthesis had already occurred by the
2:08:12
Speaker 1: time the quasar formed. The gas fueling the black hole
2:08:17
Speaker 1: had been enriched by previous generations of stars, constraining the
2:08:22
Speaker 1: timeline of star formation in the host galaxy. Metallicity measurements
2:08:27
Speaker 1: quantify these abundances relative to hydrogen. Solar metallicity refers to
2:08:34
Speaker 1: the chemical composition of our sun. About 2% of its
2:08:38
Speaker 1: mass consists of elements heavier than helium. Measurements of TON
2:08:46
Speaker 1: 618's broadline region suggest metallicities approaching or exceeding solar values,
2:08:52
Speaker 1: implying substantial prior star formation. This enrichment occurred within the
2:08:57
Speaker 1: first billion years of the galaxy's existence, requiring rapid star
2:09:01
Speaker 1: formation rates and efficient mixing of stellar ejecta throughout the
2:09:06
Speaker 1: interstellar medium. Dust observations provide additional constraints. Dust grains form
2:09:15
Speaker 1: when heavy elements condense in the cool outflows from dying stars.
2:09:20
Speaker 1: Infrared observations detect thermal emission from dust heated by starlight
2:09:25
Speaker 1: or quasar radiation. The infrared luminosity indicates the dust mass
2:09:31
Speaker 1: and temperature, revealing the star formation history and the balance
2:09:36
Speaker 1: between dust production and destruction. For TON618, infrared observations show
2:09:45
Speaker 1: substantial dust consistent with vigorous star formation, either currently ongoing
2:09:51
Speaker 1: or in the recent past. Star formation rates in the
2:09:55
Speaker 1: host galaxy remain uncertain due to contamination from quasar light.
2:10:01
Speaker 1: Typical estimates for luminous quasars at similar redshifts suggest rates
2:10:06
Speaker 1: of hundreds to thousands of solar masses per year. If
2:10:11
Speaker 1: TON618' s host galaxy forms stars at this pace, it would
2:10:16
Speaker 1: build a stellar mass exceeding a trillion solar masses within
2:10:19
Speaker 1: a billion years, consistent with the implied galaxy mass from
2:10:24
Speaker 1: the black hole galaxy correlation. Such rapid star formation requires
2:10:29
Speaker 1: enormous gas reservoirs and efficient conversion of gas into stars.
2:10:35
Speaker 1: Stellar initial mass function affects predictions. This function describes the
2:10:40
Speaker 1: relative numbers of stars formed at different masses. A standard
2:10:45
Speaker 1: IMF produces mostly low-mass stars with fewer massive stars. Alternative
2:10:52
Speaker 1: IMFs with more massive stars would yield different chemical enrichment patterns, luminosities,
2:10:58
Speaker 1: and feedback effects. Observations of stellar populations in distant galaxies
2:11:04
Speaker 1: suggest that the IMF may vary with redshift or environment,
2:11:09
Speaker 1: complicating interpretations of star formation rates and chemical evolution. Supernova
2:11:16
Speaker 1: feedback influences both star formation and black hole growth. Massive
2:11:21
Speaker 1: stars explode as supernovae after only a few million years,
2:11:26
Speaker 1: injecting energy and momentum into surrounding gas. This feedback heats
2:11:31
Speaker 1: and disperses gas, potentially suppressing subsequent star formation. In dense environments,
2:11:39
Speaker 1: supernovae might trigger star formation by compressing nearby gas clouds.
2:11:45
Speaker 1: The balance between suppression and triggering determines the overall star
2:11:50
Speaker 1: formation efficiency and the timescale over which galaxies build their
2:11:55
Speaker 1: stellar populations. Active galactic nucleus feedback operates on larger scales.
2:12:03
Speaker 1: Radiation pressure, jets, and winds driven by the central black
2:12:08
Speaker 1: hole affect the entire galaxy and its circumgalactic medium. This
2:12:13
Speaker 1: feedback can quench star formation by heating or expelling gas,
2:12:19
Speaker 1: explaining why the most massive galaxies observed today have relatively
2:12:24
Speaker 1: low star formation rates despite their large gas reservoirs. TON
2:12:30
Speaker 1: 618's powerful feedback likely regulates star formation in its host
2:12:35
Speaker 1: potentially transitioning the galaxy from an active star-forming phase to
2:12:40
Speaker 1: a quiescent, passive phase. Observations of other massive galaxies suggest
2:12:47
Speaker 1: this transition occurred in the past several billion years. Massive
2:12:53
Speaker 1: elliptical galaxies in the nearby universe contain old stellar populations,
2:12:58
Speaker 1: with little ongoing star formation. These galaxies likely experienced intense
2:13:05
Speaker 1: starburst phases at high redshift, then quenched due to AGN feedback,
2:13:11
Speaker 1: or exhaustion of gas supplies. TON618 may represent an earlier
2:13:18
Speaker 1: stage in this evolutionary sequence, captured during the peak of
2:13:22
Speaker 1: both black hole growth and star formation, before feedback mechanisms
2:13:27
Speaker 1: shut down both processes. Merger histories affect structure. Hierarchical structure
2:13:33
Speaker 1: formation predicts that massive galaxies assembled through numerous mergers of
2:13:38
Speaker 1: smaller galaxies. Each merger brings gas that can fuel starbursts
2:13:43
Speaker 1: and black hole accretion. The stellar populations formed during different
2:13:48
Speaker 1: merger events have distinct ages and metallicities, creating complex distributions
2:13:54
Speaker 1: that observations can potentially disentangle. TON618' s host likely experienced multiple
2:14:04
Speaker 1: major mergers, each contributing to its current mass and triggering
2:14:09
Speaker 1: episodes of quasar activity. Dynamical modeling reconstructs these histories. Simulations
2:14:16
Speaker 1: that reproduce observed properties reveal plausible formation pathways. For TON618,
2:14:23
Speaker 1: models must explain how the black hole grew so massive
2:14:27
Speaker 1: so quickly while simultaneously building the host galaxy's stellar population.
2:14:34
Speaker 1: Successful models typically invoke either continuous rapid accretion from dense
2:14:39
Speaker 1: gas streams, or episodic bursts of accretion triggered by mergers.
2:14:46
Speaker 1: Both scenarios require specific initial conditions and environmental factors that
2:14:52
Speaker 1: may be rare. explaining why ultramassive black holes like TON618
2:14:58
Speaker 1: are uncommon. Observational biases affect discovery rates. Luminous quasars are
2:15:06
Speaker 1: easier to detect than faint ones, so surveys naturally find
2:15:10
Speaker 1: the brightest examples like TON618. Fainter quasars with smaller black
2:15:16
Speaker 1: holes might outnumber the ultramassive ones, but remain undetected. due
2:15:22
Speaker 1: to instrumental sensitivity limits. Correcting for these biases requires careful
2:15:29
Speaker 1: statistical analysis of survey selection functions, allowing astronomers to infer
2:15:35
Speaker 1: the true number density of black holes at different masses.
2:15:39
Speaker 1: Variability studies track changes over time. Quasars vary in brightness
2:15:45
Speaker 1: due to fluctuations in accretion rate or changes in obscuration.
2:15:51
Speaker 1: TON 618 over months or years, could reveal variability patterns
2:15:57
Speaker 1: that constrain the accretion disk's size and structure. Shorter timescale
2:16:02
Speaker 1: variations probe smaller spatial regions closer to the black hole,
2:16:07
Speaker 1: while longer-term trends reflect changes in the overall fuel supply
2:16:12
Speaker 1: or feedback processes. Spectroscopic monitoring detects changes in emission line profiles,
2:16:20
Speaker 1: If the broadline region's structure evolves, line widths and intensities
2:16:26
Speaker 1: shift accordingly. Reverberation mapping exploits these changes to measure the
2:16:32
Speaker 1: region's size by timing the delay between continuum variations and
2:16:38
Speaker 1: line response. For ton 618, such measurements would refine black
2:16:45
Speaker 1: hole mass estimates and test whether the broadline region's properties
2:16:49
Speaker 1: differ from those in less extreme systems. Polarization measurements reveal
2:16:55
Speaker 1: magnetic field geometries and scattering processes. Light from the accretion
2:17:01
Speaker 1: disk becomes polarized through scattering off electrons or alignment of
2:17:06
Speaker 1: dust grains by magnetic fields. The degree and direction of
2:17:12
Speaker 1: polarization encode information about field strength. orientation, and the distribution
2:17:19
Speaker 1: of scattering material. For TON618, polarization data would constrain jet
2:17:28
Speaker 1: magnetic fields and accretion disk structure, complementing spectroscopic and photometric observations.
2:17:37
Speaker 1: The broader cosmological context matters, TON618 formed during an epoch
2:17:44
Speaker 1: when the universe's structure was rapidly evolving. The cosmic star
2:17:49
Speaker 1: formation rate peaked around Redshift 2, then declined as gas
2:17:53
Speaker 1: was consumed and feedback mechanisms became more efficient. Understanding why
2:17:59
Speaker 1: this transition occurred requires studying objects like T-O-N-618 that exemplify
2:18:06
Speaker 1: the peak phase. Their properties constrain models of gas accretion,
2:18:12
Speaker 1: star formation, and feedback that govern galaxy evolution. Dark energy's
2:18:18
Speaker 1: influence becomes relevant on the largest scales. The accelerated expansion
2:18:23
Speaker 1: of the universe affects structure growth by counteracting gravitational collapse.
2:18:30
Speaker 1: In the distant future, dark energy will prevent new structures
2:18:33
Speaker 1: from forming. and eventually tear apart gravitationally bound systems. But
2:18:40
Speaker 1: during Ton's epoch, dark energy's effects were minimal, allowing structures
2:18:47
Speaker 1: to grow rapidly through gravitational instability. The current dominance of
2:18:53
Speaker 1: dark energy marks a transition point in cosmic history, after
2:18:58
Speaker 1: which structure formation slows dramatically. 618 offers a window into
2:19:06
Speaker 1: processes that shaped the universe. Its extreme properties, ultra-massive black hole,
2:19:13
Speaker 1: intense luminosity, enormous nebula, powerful jets, reflect conditions in the
2:19:19
Speaker 1: early universe that no longer prevail. Studying this system reveals
2:19:24
Speaker 1: how galaxies formed from primordial gas, how black holes grew
2:19:30
Speaker 1: to dominate galactic centers, and how feedback regulated the transformation
2:19:36
Speaker 1: from actively star-forming systems to passive ellipticals. Every observation adds
2:19:43
Speaker 1: another piece to this cosmic puzzle. The system's fate remains
2:19:48
Speaker 1: uncertain over cosmic timescales. Will the black hole continue growing
2:19:53
Speaker 1: through mergers, eventually exceeding theoretical mass limits? Will feedback mechanisms
2:20:01
Speaker 1: shut down accretion permanently, leaving a quiescent remnant? Will the
2:20:06
Speaker 1: host galaxy merge with neighbours, triggering new episodes of activity?
2:20:13
Speaker 1: These questions await answers that observations over coming decades will provide.
2:20:19
Speaker 1: What we know today represents a beginning. TON618 challenges our understanding.
2:20:27
Speaker 1: and pushes theoretical models to their limits. It exemplifies the
2:20:32
Speaker 1: universe's capacity for extremes, objects so massive, so luminous, so energetic,
2:20:40
Speaker 1: that they redefine what we consider possible. In studying this
2:20:44
Speaker 1: cosmic giant, we confront fundamental questions about growth, limits, and
2:20:50
Speaker 1: the processes that govern the largest structures in existence. The
2:20:54
Speaker 1: numbers don't lie. but they don't quite capture it either.
2:20:59
Speaker 1: You now know that TON 618's event horizon spans 2,600
2:21:05
Speaker 1: astronomical units. You understand that light takes weeks to cross
2:21:10
Speaker 1: its shadow. You've grasped that it outmasses every star in
2:21:15
Speaker 1: our galaxy combined. But knowing these facts and truly comprehending
2:21:20
Speaker 1: them remain different things entirely. Your brain isn't wired for
2:21:24
Speaker 1: this scale. Evolution shaped your intuitions for objects measured in meters,
2:21:30
Speaker 1: distances covered in hours, masses you can lift, or at
2:21:35
Speaker 1: least imagine lifting. Ton. 618 exists so far outside this
2:21:42
Speaker 1: comfortable range that even armed with precise measurements and careful comparisons,
2:21:48
Speaker 1: you can't really picture it. The best you can do
2:21:52
Speaker 1: is understand the relationships. how it compares to things slightly
2:21:57
Speaker 1: less incomprehensible, building a ladder of analogies that points toward
2:22:04
Speaker 1: but never quite reaches the truth. What makes TON 618
2:22:09
Speaker 1: genuinely remarkable isn't just its size. Plenty of things in
2:22:14
Speaker 1: the universe are large. Galaxy clusters span millions of light years.
2:22:20
Speaker 1: Cosmic voids stretch across hundreds of millions. The observable universe
2:22:26
Speaker 1: itself measures 93 billion light years across. Size alone doesn't
2:22:32
Speaker 1: make something special. The remarkable aspect is concentration. 66 billion
2:22:39
Speaker 1: solar masses packed into a region you could traverse at
2:22:42
Speaker 1: light speed in a few weeks. That concentration creates gravitational
2:22:47
Speaker 1: fields so intense they warp spacetime into shapes that break
2:22:52
Speaker 1: your intuitive understanding. It creates energy densities that shouldn't exist
2:22:57
Speaker 1: according to some theoretical limits. It produces feedback effects that
2:23:03
Speaker 1: reshape entire galaxies across hundreds of thousands of light years.
2:23:09
Speaker 1: TON618 represents physics operating at the edge of what's possible.
2:23:16
Speaker 1: Black holes can't grow arbitrarily large through accretion. Radiation pressure
2:23:21
Speaker 1: eventually prevents further growth. Theoretical calculations put this limit around
2:23:28
Speaker 1: 50 billion solar masses for non-spinning black holes, potentially higher
2:23:34
Speaker 1: for rapidly spinning ones. Ton 618 sits right at this boundary,
2:23:40
Speaker 1: possibly already at its maximum accretion-based mass. It's not just big,
2:23:46
Speaker 1: it's as big as a black hole can get through
2:23:48
Speaker 1: the standard growth mechanism. The timeline makes it worse. This
2:23:54
Speaker 1: object assembled its mass within 3 billion years of the
2:23:57
Speaker 1: Big Bang. Standard growth models struggle to explain this. You
2:24:03
Speaker 1: can't simply start with a stellar mass black hole and
2:24:07
Speaker 1: grow it to 66 billion solar masses in that time
2:24:11
Speaker 1: frame using conventional accretion. The math doesn't work. Something unusual happened.
2:24:20
Speaker 1: Either the seed black hole started much more massive than
2:24:23
Speaker 1: stellar remnants typically provide, or accretion proceeded faster than theoretical
2:24:29
Speaker 1: limits suggest, or multiple massive black holes merged in rapid succession,
2:24:36
Speaker 1: or all three occurred simultaneously. We don't know which explanation
2:24:41
Speaker 1: is correct. Each has problems. Direct collapse scenarios require special
2:24:47
Speaker 1: conditions that may not have been common. Super-Eddington accretion faces
2:24:53
Speaker 1: stability issues. Rapid merger sequences seem statistically unlikely. Yet TON
2:25:01
Speaker 1: 618 exists anyway, indifferent to our theoretical difficulties. The surrounding
2:25:08
Speaker 1: nebula adds another layer to this puzzle. 100 billion solar
2:25:13
Speaker 1: masses of gas extending 330,000 light-years, twice the Milky Way's diameter.
2:25:21
Speaker 1: This isn't just decoration. It's fuel. It's the raw material
2:25:27
Speaker 1: for future star formation or continued black hole growth. The
2:25:32
Speaker 1: nebula's structure, aligned with the radio jets, shows how the
2:25:36
Speaker 1: black hole has already shaped its environment on galactic scales.
2:25:42
Speaker 1: Radiation and outflows have redistributed gas, heated it, ionized it,
2:25:48
Speaker 1: preventing it from cooling and collapsing into stars. This feedback
2:25:54
Speaker 1: mechanism explains why massive galaxies today contain relatively little cold
2:25:59
Speaker 1: gas despite their enormous masses. Their central black holes expelled
2:26:05
Speaker 1: or heated most of it during earlier active phases. TON
2:26:11
Speaker 1: 618 shows us this process in action. the moment when
2:26:15
Speaker 1: a quasar is actively regulating its own fuel supply and
2:26:19
Speaker 1: suppressing star formation throughout its host galaxy. Eventually the fuel
2:26:24
Speaker 1: runs out, the quasar dims, and the heated gas cools
2:26:29
Speaker 1: over hundreds of millions of years before forming the next
2:26:32
Speaker 1: generation of stars. That future state represents what astronomers call
2:26:38
Speaker 1: a red and dead galaxy. Massive, elliptical, containing old stellar
2:26:44
Speaker 1: populations with little ongoing star formation. Our observations suggest most
2:26:50
Speaker 1: massive ellipticals in the nearby universe went through quasar phases
2:26:54
Speaker 1: billions of years ago. TON618 provides a window into that
2:27:00
Speaker 1: earlier epoch, showing us what these systems looked like during
2:27:05
Speaker 1: their violent youth. The jets deserve emphasis. Streams of plasma
2:27:12
Speaker 1: accelerated to 99.9% light speed, carrying power equivalent to a
2:27:18
Speaker 1: trillion suns, extending across hundreds of thousands of light years.
2:27:24
Speaker 1: These aren't side effects. They're integral to how supermassive black
2:27:28
Speaker 1: holes influence their environments. The jets inject energy throughout the
2:27:34
Speaker 1: circumgalactic medium, heating gas and maintaining it at temperatures too
2:27:39
Speaker 1: high for star formation. They shape the distribution of gas
2:27:43
Speaker 1: on scales far larger than the accretion disk, or even
2:27:48
Speaker 1: the host galaxy itself. Magnetic fields thread through the entire system,
2:27:55
Speaker 1: though we can't observe them directly. Theory predicts strong fields
2:28:00
Speaker 1: near the event horizon, where they extract rotational energy from
2:28:04
Speaker 1: the spinning black hole and channel it into the jets.
2:28:10
Speaker 1: Fields in the accretion disk affect how matter spirals inward.
2:28:16
Speaker 1: Fields in the nebula might influence gas dynamics and future
2:28:21
Speaker 1: star formation. Understanding these fields requires polarisation measurements and radio
2:28:28
Speaker 1: observations that push current instruments to their limits. The host
2:28:33
Speaker 1: galaxy remains essentially invisible, outshone by the central quasar despite
2:28:39
Speaker 1: potentially containing hundreds of billions of stars. We can infer
2:28:44
Speaker 1: its properties from the black hole galaxy-mass relationship observed in
2:28:49
Speaker 1: nearby systems, but we can't observe it directly. Future telescopes
2:28:55
Speaker 1: like JWST or the Extremely Large Telescope might eventually resolve details,
2:29:02
Speaker 1: but for now, the galaxy is lost in the glare
2:29:05
Speaker 1: of the accretion disk's brilliance. This creates an odd situation
2:29:10
Speaker 1: where we know more about the black hole, an object
2:29:14
Speaker 1: we can't see directly, than about the galaxy surrounding it,
2:29:19
Speaker 1: which should be far easier to observe. The black hole's
2:29:23
Speaker 1: mass comes from measuring velocities of orbiting gas in the
2:29:27
Speaker 1: broad-line region. The galaxy's stellar population remains hidden, revealed only
2:29:33
Speaker 1: through gravitational effects and statistical relationships with other systems. Discovery
2:29:40
Speaker 1: histories often reveal something about scientific progress. TON 618 was
2:29:47
Speaker 1: photographed in 1957. catalogued as a mysterious violet object, then
2:29:54
Speaker 1: sat in records for 13 years before anyone realised what
2:29:58
Speaker 1: it was. Only after quasars were recognised as a distinct
2:30:02
Speaker 1: class of objects in 1963, and after radio observations flagged
2:30:08
Speaker 1: it as unusual in 1970, did spectroscopy reveal its true nature.
2:30:14
Speaker 1: We observed it decades before understanding it. This pattern repeats
2:30:20
Speaker 1: throughout astronomy. We detect signals, catalogue objects, take images, and
2:30:26
Speaker 1: only later, sometimes much later, do we grasp their significance.
2:30:32
Speaker 1: The delay reflects both technological limitations and conceptual ones. Sometimes
2:30:38
Speaker 1: we lack instruments sensitive enough to observe crucial details. Sometimes
2:30:44
Speaker 1: we lack the theoretical framework to interpret what we're seeing.
2:30:49
Speaker 1: Progress requires both better observations and better theories, each informing
2:30:55
Speaker 1: the other. For TON618, key questions remain unanswered. We don't
2:31:02
Speaker 1: know its precise three-dimensional structure. Observations provide projections on the sky,
2:31:08
Speaker 1: but not depth information. We don't know the detailed velocity
2:31:13
Speaker 1: field throughout the nebula. We don't know how magnetic fields
2:31:18
Speaker 1: vary spatially. We don't know the metallicity distribution in different regions.
2:31:24
Speaker 1: We don't know whether previous active phases occurred before the
2:31:28
Speaker 1: one we observe. Future observations will address some of these gaps.
2:31:34
Speaker 1: JWST can probe dusty regions invisible at optical wavelengths. The
2:31:41
Speaker 1: Extremely Large Telescope will resolve structures ten times smaller than
2:31:46
Speaker 1: current observations achieve. The square-kilometer array will map molecular gas
2:31:53
Speaker 1: and magnetic fields with unprecedented detail. Gravitational wave detectors might
2:31:59
Speaker 1: eventually sense mergers involving similarly massive black holes, revealing formation
2:32:05
Speaker 1: pathways and growth histories. But some questions may remain permanently unanswerable.
2:32:12
Speaker 1: We observe TON 618 as it was 10.8 million billion
2:32:19
Speaker 1: years ago. The light we see has been traveling since
2:32:23
Speaker 1: the universe was only three billion years old. We have
2:32:27
Speaker 1: no information about what's happened since then. The system has
2:32:32
Speaker 1: evolved for 10.8 billion years in ways we can't observe.
2:32:38
Speaker 1: The quasar might still be active, or it might have
2:32:41
Speaker 1: shut down billions of years ago. The nebula might have
2:32:45
Speaker 1: formed stars. or it might remain diffuse. We simply don't know.
2:32:51
Speaker 1: This limitation applies to all high redshift observations. We see
2:32:56
Speaker 1: distant objects as they were long ago, frozen in time
2:33:01
Speaker 1: at whatever epoch their light departed. The universe has continued evolving,
2:33:07
Speaker 1: but that evolution remains hidden from us, blocked by the
2:33:11
Speaker 1: finite speed of light. Only by observing many similar systems
2:33:16
Speaker 1: at different redshifts can we reconstruct the evolutionary sequence, piecing
2:33:22
Speaker 1: together cosmic history from snapshots at different epochs. Ton 618
2:33:29
Speaker 1: occupies a crucial position in that sequence. It formed during
2:33:33
Speaker 1: the peak of quasar activity, when black hole growth rates
2:33:37
Speaker 1: and star formation rates both reached their cosmic maxima. Understanding
2:33:43
Speaker 1: this epoch reveals how galaxies transitioned from gas-rich, actively forming
2:33:49
Speaker 1: systems to gas-poor, passive ones. It shows us when and
2:33:54
Speaker 1: how feedback mechanisms became effective at regulating growth. It constrains
2:34:01
Speaker 1: models of cosmic evolution that predict the properties of galaxies
2:34:05
Speaker 1: we observe today. The broader implications extend beyond individual objects.
2:34:11
Speaker 1: Ultramassive black holes like TON 618 provide tests of fundamental
2:34:17
Speaker 1: physics in extreme conditions. General relativity predicts how spacetime should
2:34:23
Speaker 1: curve near such massive objects, but we've never tested those
2:34:27
Speaker 1: predictions in regimes this extreme. The event horizon should behave
2:34:32
Speaker 1: in specific ways. Tidal forces should follow predictable patterns. Time
2:34:38
Speaker 1: dilation should match theoretical calculations. Confirming these predictions validates our
2:34:45
Speaker 1: understanding of gravity where it matters most. Quantum effects remain mysterious.
2:34:52
Speaker 1: Hawking radiation suggests black holes emit thermal radiation and eventually evaporate,
2:34:59
Speaker 1: but the timescale for ton 618 exceeds 10 to the
2:35:04
Speaker 1: power of 100 years, so long that the concept of
2:35:07
Speaker 1: time itself becomes questionable. The information paradox asks what happens
2:35:13
Speaker 1: to information that falls into a black hole, and no
2:35:17
Speaker 1: consensus answer exists despite decades of theoretical work. TON 618
2:35:25
Speaker 1: embodies this paradox as dramatically as any object can. String
2:35:29
Speaker 1: theory and quantum gravity approaches proposed solutions, but experimental tests
2:35:36
Speaker 1: remain impossible with current technology. We can't probe physics at
2:35:42
Speaker 1: the Planck scale where quantum effects should modify general relativity.
2:35:47
Speaker 1: We can't observe the interior of event horizons where singularities
2:35:52
Speaker 1: supposedly lurk. We're left with mathematics and theoretical arguments, unable
2:35:58
Speaker 1: to test predictions directly. TON 618 reminds us that the
2:36:04
Speaker 1: universe contains regimes where our best theories break down. And
2:36:09
Speaker 1: new physics must eventually emerge. The scale still doesn't quite register.
2:36:14
Speaker 1: You can recite the numbers. 1,300 astronomical units Schwarzschild radius.
2:36:21
Speaker 1: 66 billion solar masses. 140 trillion times solar luminosity. You
2:36:28
Speaker 1: can follow the comparisons. 40 times Neptune's orbit. More massive
2:36:33
Speaker 1: than the Milky Way's stars combined. Light takes weeks to
2:36:37
Speaker 1: cross its shadow. but actually visualizing it, actually grasping what
2:36:42
Speaker 1: those numbers mean in any visceral sense. That remains beyond
2:36:48
Speaker 1: human capability. Your brain compresses the information into abstractions. TON618
2:36:56
Speaker 1: becomes a category, ultramassive black hole, rather than a thing
2:37:01
Speaker 1: you can imagine. The nebula becomes a number, 100 billion
2:37:06
Speaker 1: solar masses. rather than a physical structure you can picture.
2:37:11
Speaker 1: The jets become a concept, relativistic outflows, rather than actual
2:37:17
Speaker 1: streams of plasma you can visualize. The translation from measurement
2:37:22
Speaker 1: to understanding hits fundamental cognitive limits. This limitation isn't failure,
2:37:29
Speaker 1: it's recognition. of scope. The universe operates at scales both
2:37:34
Speaker 1: far smaller and far larger than human experience spans. Quarks
2:37:40
Speaker 1: and electrons inhabit realms trillions of times smaller than anything
2:37:44
Speaker 1: you can see. Galaxy superclusters and cosmic voids extend billions
2:37:51
Speaker 1: of light years beyond anything you can travel to. Your intuitions,
2:37:56
Speaker 1: shaped by evolution to navigate a world of medium-sized objects
2:38:01
Speaker 1: moving at moderate speeds, simply weren't designed for extremes in
2:38:06
Speaker 1: either direction. What you can grasp is relationship and context.
2:38:12
Speaker 1: TON 618 isn't just large. It's among the largest black
2:38:17
Speaker 1: holes known. It isn't just distant. It's one of the
2:38:21
Speaker 1: most distant quasars we've studied in detail. It isn't just massive.
2:38:27
Speaker 1: It's at or near the theoretical maximum mass achievable through accretion.
2:38:34
Speaker 1: These relationships place it in context, showing where it fits
2:38:39
Speaker 1: in the cosmic hierarchy of extreme objects. You can also
2:38:44
Speaker 1: grasp implication. TON 618's existence tells us something about the
2:38:51
Speaker 1: early universe, that conditions allowed such massive black holes to
2:38:56
Speaker 1: form within 3 billion years. Its properties constrain theoretical models
2:39:02
Speaker 1: of black hole growth and galaxy evolution. Its feedback effects
2:39:07
Speaker 1: demonstrate how black holes influence their environments on scales far
2:39:12
Speaker 1: exceeding their physical size. These implications connect TON 618 to
2:39:19
Speaker 1: broader questions about cosmic structure and evolution. The human tendency
2:39:24
Speaker 1: to seek meaning in observations runs deep. You look at
2:39:29
Speaker 1: TON 618 and want to know what it means. what
2:39:33
Speaker 1: significance it holds beyond just being large and distant. The
2:39:38
Speaker 1: scientific answer focuses on what we learn, constraints on accretion physics,
2:39:44
Speaker 1: tests of general relativity, insights into galaxy formation. But there's
2:39:50
Speaker 1: another meaning, less precise, but perhaps more profound. TON 618
2:39:58
Speaker 1: represents the universe's capacity for extremes. Physics allows black holes
2:40:04
Speaker 1: to exist. The laws of nature permit matter to collapse
2:40:08
Speaker 1: into regions so dense that space-time itself warps beyond recognition.
2:40:15
Speaker 1: The same forces that shape ordinary stars and planets, scaled
2:40:19
Speaker 1: up and concentrated, produce objects that challenge our ability to understand.
2:40:26
Speaker 1: The universe isn't obligated to operate at scales we find
2:40:30
Speaker 1: comfortable or comprehensible, It simply operates according to its laws,
2:40:36
Speaker 1: producing whatever those laws allow. This indifference to human comprehension
2:40:42
Speaker 1: is itself significant. The universe doesn't care whether we understand it.
2:40:48
Speaker 1: TON618 existed long before humans evolved, will continue existing long
2:40:55
Speaker 1: after our species is gone, and would remain exactly as
2:40:59
Speaker 1: it is, even if no conscious observers ever studied it.
2:41:05
Speaker 1: Our attempts to measure and understand it reflect our curiosity,
2:41:10
Speaker 1: not any intrinsic meaning the object possesses. Yet that curiosity matters.
2:41:16
Speaker 1: Humans are the universe's way of studying itself, matter arranged
2:41:21
Speaker 1: in such a way that it can contemplate its own
2:41:24
Speaker 1: existence and origins. When you think about Ton 618, When
2:41:30
Speaker 1: you grapple with its scale and try to understand its properties,
2:41:35
Speaker 1: you're participating in something remarkable. Atoms forged in ancient stars,
2:41:42
Speaker 1: now arranged into a human brain, considering the nature of
2:41:46
Speaker 1: an ultra-massive black hole billions of light-years away. The universe
2:41:52
Speaker 1: examining itself through the medium of consciousness. That's the real
2:41:57
Speaker 1: story TON618 tells. Not just facts about mass and size
2:42:03
Speaker 1: and luminosity, though those are important. Not just implications for
2:42:08
Speaker 1: cosmology and galaxy evolution, though those matter too. The deeper
2:42:14
Speaker 1: story is about the relationship between the universe and the
2:42:17
Speaker 1: minds that try to understand it. How we push against
2:42:21
Speaker 1: the limits of comprehension, developing mathematics and observations and theories
2:42:27
Speaker 1: to grasp phenomena that exceed our intuitive capabilities. The effort
2:42:33
Speaker 1: itself is valuable regardless of how complete our understanding becomes.
2:42:39
Speaker 1: We'll never stand on a planet orbiting TON618, never directly
2:42:45
Speaker 1: observe its event horizon, never witness its eventual fate billions
2:42:51
Speaker 1: of years from now. But we can measure its properties,
2:42:55
Speaker 1: model its evolution, connect it to theoretical frameworks that explain
2:43:00
Speaker 1: how such objects form and grow. We can place it
2:43:04
Speaker 1: in context, understand its significance, and use it to test
2:43:09
Speaker 1: our theories about the cosmos. That's what science offers. Not
2:43:13
Speaker 1: complete understanding, but progressive refinement of incomplete understanding. Each observation
2:43:21
Speaker 1: adds detail. Each measurement constrains theories, Each new instrument reveals
2:43:28
Speaker 1: previously hidden aspects. The process continues, building knowledge incrementally, occasionally
2:43:35
Speaker 1: making dramatic leaps when new technologies or insights become available.
2:43:41
Speaker 1: TON618 will continue revealing secrets as our capabilities improve. JWST
2:43:49
Speaker 1: observations might resolve the host galaxy's structure. Gravitational wave detectors
2:43:56
Speaker 1: might sense mergers involving similar objects. Advanced simulations might explain
2:44:02
Speaker 1: how it grew so massive so quickly. Future generations of
2:44:06
Speaker 1: astronomers will study it with instruments we haven't yet imagined,
2:44:11
Speaker 1: asking questions we haven't yet formulated. For now, you know
2:44:16
Speaker 1: what can be known from current observations. You understand the
2:44:20
Speaker 1: scale even if you can't truly visualize it. You grasp
2:44:24
Speaker 1: the implications even if the full picture remains incomplete. You've
2:44:29
Speaker 1: confronted one of the most extreme objects in the universe
2:44:33
Speaker 1: and emerged with some measure of understanding, however limited human
2:44:38
Speaker 1: comprehension must be when faced with phenomena this far beyond
2:44:44
Speaker 1: everyday experience. The universe contains TON618 and countless other wonders,
2:44:52
Speaker 1: objects and phenomena that push the boundaries of what physics allows.
2:44:58
Speaker 1: Some we've discovered. Many more await detection. Each one challenges
2:45:03
Speaker 1: us to expand our understanding, to develop new ways of
2:45:07
Speaker 1: thinking about matter, energy, space, and time. Each one reminds
2:45:13
Speaker 1: us that reality is richer and stranger than we might imagine.
2:45:18
Speaker 1: That's how Big Ton 618 really is. not just in
2:45:23
Speaker 1: astronomical units or solar masses, but in the space it
2:45:27
Speaker 1: occupies in our attempts to understand the cosmos, a landmark
2:45:31
Speaker 1: at the edge of comprehension, pointing toward mysteries that still
2:45:35
Speaker 1: await resolution.