Latest / Boring Science / Porphyrion _ A Galaxy That Stretches 23 Million Light Years _ Largest Galaxy _ Science For Sleep

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Porphyrion _ A Galaxy That Stretches 23 Million Light Years _ Largest Galaxy _ Science For Sleep · Boring Science

• 0:00
  Speaker 1: A black hole at the center of a small galaxy
• 0:02
  Speaker 1: just produced something 140 times wider than our entire Milky Way.
• 0:08
  Speaker 1: Not the galaxy itself, not a structure inside it. Something
• 0:13
  Speaker 1: that erupted from it, stretched outward in two directions, and
• 0:17
  Speaker 1: kept going for 23 million light years. To put that
• 0:22
  Speaker 1: number somewhere useful, the distance from here to the Andromeda Galaxy,
• 0:26
  Speaker 1: our nearest large neighbor, is 2.5 million light years. Porphyreon
• 0:32
  Speaker 1: is nearly 10 times longer than that. End to end,
• 0:36
  Speaker 1: this is not a galaxy in the way most people
• 0:38
  Speaker 1: picture one. It is a pair of jets, plasma launched
• 0:42
  Speaker 1: at mere light speed from a supermassive black hole, shooting
• 0:45
  Speaker 1: outward above and below, traveling farther than any structure produced
• 0:50
  Speaker 1: by a single galaxy has ever been measured to travel.
• 0:53
  Speaker 1: And the thing that produced all of it, the engine
• 0:56
  Speaker 1: at the center, sits inside a galaxy smaller than the
• 1:00
  Speaker 1: Milky Way. That is the paradox. A modest galaxy. An
• 1:05
  Speaker 1: almost incomprehensible output. The jets reach two-thirds of the way
• 1:10
  Speaker 1: into the cosmic void. Not between galaxies. Between superclusters of galaxies.
• 1:16
  Speaker 1: Out into the empty filaments and dark corridors of the
• 1:19
  Speaker 1: cosmic web. The largest architecture in the universe. Until Porphyrian,
• 1:25
  Speaker 1: No black hole jet had ever been shown to operate
• 1:28
  Speaker 1: at that scale. The cosmic web was supposed to be
• 1:31
  Speaker 1: purely gravitational territory, something shaped by dark matter and the
• 1:36
  Speaker 1: slow accumulation of mass over billions of years. Porphyrian suggested
• 1:41
  Speaker 1: the picture was missing something. If you find comfort in
• 1:44
  Speaker 1: these gentle explorations of space and science, I'd be grateful
• 1:49
  Speaker 1: if you'd consider subscribing and giving this video a like.
• 1:53
  Speaker 1: I'd love to know where you're watching from and what
• 1:55
  Speaker 1: time it is for you. Feel free to drop your
• 1:58
  Speaker 1: location and time in the comments below. When the Discovery
• 2:08
  Speaker 1: paper appeared in Nature in September of 2024, it carried
• 2:12
  Speaker 1: a specific and uncomfortable implication. Supermassive black holes do not
• 2:18
  Speaker 1: only shape the galaxies they live in, they can reach
• 2:21
  Speaker 1: the cosmic web itself. They can push energy into the
• 2:25
  Speaker 1: filaments that connect and feed entire galaxy clusters. If jets
• 2:30
  Speaker 1: like this were common in the early universe, and there
• 2:33
  Speaker 1: is growing evidence they were, then the structure of everything
• 2:36
  Speaker 1: we can see may carry their fingerprint. That is what
• 2:40
  Speaker 1: one black hole did. A black hole sitting inside a
• 2:44
  Speaker 1: galaxy we can only see as it existed 7.5 billion
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  Speaker 1: years ago, when the universe was barely half its current age.
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  Speaker 1: The structure was named Porphyrian, after a giant from Greek mythology,
• 2:58
  Speaker 1: a rebellious giant, one who fought the gods and refused
• 3:02
  Speaker 1: to stay where he was put. The name fits. Before
• 3:06
  Speaker 1: this discovery, the largest known jet system was Alcyoneus, also
• 3:10
  Speaker 1: named after a mythological giant, also found by the same team,
• 3:15
  Speaker 1: also using the same radio telescope network. Alcyoneus spanned roughly
• 3:20
  Speaker 1: 100 Milky Ways. Porphyrion came in at 140. The record
• 3:26
  Speaker 1: it broke had only stood for two years, and the
• 3:29
  Speaker 1: record Porphyrion set was itself broken within months. Something is
• 3:34
  Speaker 1: out there. A whole population of structures at this scale,
• 3:38
  Speaker 1: invisible to previous generations of telescopes, finally showing up in
• 3:43
  Speaker 1: surveys sensitive enough to catch them. We are not looking
• 3:47
  Speaker 1: at a single exception. We are looking at the first
• 3:50
  Speaker 1: catalogue entries of something that was always enormous and always there.
• 3:56
  Speaker 1: This story involves radio telescopes spread across an entire continent,
• 4:01
  Speaker 1: plasma travelling at nearly the speed of light, a fuel
• 4:04
  Speaker 1: source that apparently never ran out, and a revision to
• 4:08
  Speaker 1: how astronomers think black holes interact with the universe at
• 4:11
  Speaker 1: its largest scales. The numbers in this story will stop
• 4:16
  Speaker 1: making sense several times. That is expected. That is the point.
• 4:21
  Speaker 1: Now look out, because we are about to go very,
• 4:24
  Speaker 1: very far. In September of 2024, a paper appeared in
• 4:29
  Speaker 1: the journal Nature that made a very specific and very
• 4:32
  Speaker 1: large claim. The team behind it was led by Martijn Owee,
• 4:37
  Speaker 1: an astronomer working out of the California Institute of Technology.
• 4:41
  Speaker 1: They had found something. Not a new planet, not a
• 4:45
  Speaker 1: new star, not even a new galaxy in the ordinary sense.
• 4:49
  Speaker 1: What they described in that paper was a structure stretching
• 4:51
  Speaker 1: 23 million light years from end to end, produced by
• 4:56
  Speaker 1: a single supermassive black hole sitting at the center of
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  Speaker 1: a galaxy, billions of light years away. The paper did
• 5:03
  Speaker 1: not bury the headline. The abstract stated the size. The
• 5:07
  Speaker 1: figures showed the shape. And within days, the finding was
• 5:11
  Speaker 1: moving through the astronomy community the way only a handful
• 5:14
  Speaker 1: of results do, Not as a curiosity, but as something
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  Speaker 1: that forced people to stop and reconsider assumptions they had
• 5:22
  Speaker 1: not realized they were making. The object had an official designation.
• 5:27
  Speaker 1: It was cataloged as J152932. 16 plus 6015334.4, a sequence of
• 5:36
  Speaker 1: numbers and decimals that tells you its coordinates in the sky,
• 5:40
  Speaker 1: its position in the constellation Draco, and nothing at all
• 5:44
  Speaker 1: about what it actually is. Designations like that are placeholders.
• 5:49
  Speaker 1: They are how astronomers keep track of objects before those
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  Speaker 1: objects mean something. This one would not stay a placeholder
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  Speaker 1: for long. The team gave it a name. They called
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  Speaker 1: it Porphyreon, borrowed from Greek mythology, from the story of
• 6:03
  Speaker 1: the Gigantomachy, the war between the giants and the Olympian gods.
• 6:08
  Speaker 1: Porphyreon was one of the most powerful of the giants.
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  Speaker 1: In some versions of the myth, he was the king
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  Speaker 1: of them. He rebelled against the gods and had to
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  Speaker 1: be struck down by both Heracles and Zeus together. The
• 6:21
  Speaker 1: choice of name was deliberate. The thing they had found was,
• 6:25
  Speaker 1: by any reasonable measure, titanic. The name fit for another reason.
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  Speaker 1: In Greek myth, the giants were born from the earth,
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  Speaker 1: rooted in something ancient and enormous. Porphyreon the structure was
• 6:39
  Speaker 1: built from something similarly ancient. The light captured in those
• 6:43
  Speaker 1: observations had left its source 7.5 billion years ago. The universe,
• 6:48
  Speaker 1: by best current estimates, is 13.8 billion years old. That
• 6:54
  Speaker 1: means astronomers were looking at a structure that existed when
• 6:57
  Speaker 1: the universe was roughly 6.3 billion years old, less than
• 7:02
  Speaker 1: half its present age. The cosmos was younger, denser, and
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  Speaker 1: in certain measurable ways, more compressed. What Porphyrian was doing
• 7:12
  Speaker 1: inside that younger universe, what it was reaching across, would
• 7:16
  Speaker 1: turn out to matter enormously. But before any of that
• 7:20
  Speaker 1: context became clear, the paper first had to establish the
• 7:24
  Speaker 1: raw fact of the size. Previous surveys had found large
• 7:28
  Speaker 1: jet structures before. Giant radio galaxies, that is the technical
• 7:33
  Speaker 1: term for objects like this, had been catalogued going back decades.
• 7:38
  Speaker 1: most of the well-known ones spanned a few million light
• 7:41
  Speaker 1: years at most. The record, such as it was, had
• 7:45
  Speaker 1: been broken in 2022. The same team led by OEA
• 7:50
  Speaker 1: had announced a structure called Alcyoneus, also named after one
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  Speaker 1: of the giants from the same myth, also found using
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  Speaker 1: the same radio telescope, spanning roughly 16 million light years.
• 8:03
  Speaker 1: That was, at the time, the largest known structure of
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  Speaker 1: its kind, It held the record for two years. Then
• 8:10
  Speaker 1: Porphyrian came in at 23 million light years, surpassing it
• 8:15
  Speaker 1: by 7 million. That is not a marginal improvement. 7
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  Speaker 1: million light years is 70 times the diameter of the
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  Speaker 1: Milky Way. The record did not inch forward. It jumped.
• 8:28
  Speaker 1: Here is why that matters. When a record moves by
• 8:31
  Speaker 1: small increments, it usually means the phenomenon is well understood
• 8:34
  Speaker 1: and researchers are refining measurements at the edges. When a
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  Speaker 1: record moves in large jumps, it often means something else.
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  Speaker 1: It means the underlying population of objects is not fully mapped.
• 8:47
  Speaker 1: It means the surveys and instruments being used have not
• 8:50
  Speaker 1: been sensitive enough to capture the full range of what
• 8:53
  Speaker 1: is out there. The jump from Alcyoneus to Porphyrian did
• 8:57
  Speaker 1: not suggest that Porphyrian was a freakish outlier. It suggested
• 9:01
  Speaker 1: that the tools being pointed at the sky were only
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  Speaker 1: recently powerful enough to see objects at this scale at all.
• 9:08
  Speaker 1: and that more were waiting to be found. The paper
• 9:11
  Speaker 1: made one additional claim that went beyond the record itself.
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  Speaker 1: Porphyrian was not merely the largest jet structure ever catalogued,
• 9:20
  Speaker 1: it was the first black hole jet to reach the
• 9:22
  Speaker 1: scale of the cosmic web. The cosmic web is the
• 9:26
  Speaker 1: term astronomers use for the large-scale architecture of the universe,
• 9:30
  Speaker 1: a vast network of filaments and voids, with galaxies strung
• 9:34
  Speaker 1: along the filaments like beads on an enormous, three-dimensional thread.
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  Speaker 1: These filaments are among the largest structures in existence. Clusters
• 9:44
  Speaker 1: and superclusters of galaxies sit where filaments intersect. Between them
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  Speaker 1: stretch regions called voids, enormous volumes where almost nothing lives.
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  Speaker 1: Porphyrian's jets extended two-thirds of the way into one of
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  Speaker 1: those voids. Two-thirds of the distance from where galaxies cluster
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  Speaker 1: to where almost nothing exists. No jet had done that before.
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  Speaker 1: No single galaxy-produced structure had ever been confirmed at that scale.
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  Speaker 1: This distinction was not a technicality. It changed what had
• 10:15
  Speaker 1: to be explained. Until Porphyrian, black hole jets were understood
• 10:20
  Speaker 1: as local forces. Powerful, yes. Consequential for their host galaxies, certainly.
• 10:27
  Speaker 1: Occasionally influential at the scale of a galaxy cluster. But
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  Speaker 1: they were not understood as objects that could reach beyond
• 10:34
  Speaker 1: clusters entirely, that could push energy and plasma into the
• 10:38
  Speaker 1: cosmic web itself. The paper from OEI's team argued, carefully
• 10:43
  Speaker 1: and with data, that supermassive black holes do not only
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  Speaker 1: shape the galaxies they inhabit, they can shape the large-scale
• 10:51
  Speaker 1: structure surrounding those galaxies. That is a different kind of
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  Speaker 1: influence entirely. It reaches past the local neighborhood and into
• 11:00
  Speaker 1: the scaffolding of the universe. For most people, a paper
• 11:04
  Speaker 1: in a scientific journal is an endpoint. The research is done.
• 11:08
  Speaker 1: The result is published. In the world of astronomy, Publications
• 11:13
  Speaker 1: like this one are closer to ignition points. Within weeks,
• 11:16
  Speaker 1: theorists were asking what kind of environment could sustain a
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  Speaker 1: jet for the billions of years required to reach this scale.
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  Speaker 1: Observers were re-examining archival data for signs of similar structures.
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  Speaker 1: The question of whether porphyrium was exceptional or representative had
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  Speaker 1: no clean answer, and that open edge was exactly where
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  Speaker 1: the energy of the field moved. An enormous result with
• 11:39
  Speaker 1: an unresolved implication is, for astronomers, more productive than a
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  Speaker 1: clean answer. Clean answers stop conversations. This one started several.
• 11:49
  Speaker 1: And the conversations were not small. They touched on how
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  Speaker 1: the cosmic web formed, on how black holes in the
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  Speaker 1: early universe behaved differently than those in the local universe,
• 12:00
  Speaker 1: on whether the standard picture of galaxy evolution needed revision
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  Speaker 1: at scales nobody had previously bothered to model, What they
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  Speaker 1: had found was not just a record breaker, it was
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  Speaker 1: something that did not fit cleanly into the existing picture
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  Speaker 1: of how black holes behave. The first thing to understand
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  Speaker 1: about Porphyrian is that it is not a galaxy in
• 12:20
  Speaker 1: the way most people use that word. When most people
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  Speaker 1: hear galaxy they picture something like the Milky Way, a
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  Speaker 1: vast spinning disk of stars, gas and dust bound together
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  Speaker 1: by gravity. Porphyrian is not that. What astronomers named Porphyrian
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  Speaker 1: are the jets. Two enormous streams of plasma shooting outward
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  Speaker 1: from a single supermassive black hole in opposite directions, stretching
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  Speaker 1: 23 million light years from tip to tip. The galaxy
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  Speaker 1: that produced them is just the engine. The jets are
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  Speaker 1: the event. To understand how that is even possible, you
• 12:58
  Speaker 1: have to rethink what a black hole actually does. The
• 13:02
  Speaker 1: popular image is simple. A black hole swallows things. Matter
• 13:06
  Speaker 1: falls in. Nothing comes out. That image is not wrong,
• 13:10
  Speaker 1: but it is incomplete. Black holes, especially the supermassive ones
• 13:14
  Speaker 1: sitting at the centers of galaxies, are not just consumers.
• 13:19
  Speaker 1: Under the right conditions, they are among the most powerful
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  Speaker 1: ejectors in the universe. The key is what happens just
• 13:25
  Speaker 1: before matter crosses the point of no return. When a
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  Speaker 1: supermassive black hole is actively feeding, The material falling toward
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  Speaker 1: it does not fall straight in. It has angular momentum.
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  Speaker 1: It spirals. As it spirals inward, it forms a flattened
• 13:42
  Speaker 1: rotating structure called an accretion disk. Think of water draining
• 13:47
  Speaker 1: in a sink, but scaled up to billions of solar masses.
• 13:52
  Speaker 1: The material in this disk is moving fast, colliding with itself,
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  Speaker 1: heating up to temperatures of millions of degrees. At these temperatures,
• 14:00
  Speaker 1: the disk glows. It radiates enormous amounts of energy across
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  Speaker 1: the electromagnetic spectrum. A black hole with an active accretion
• 14:09
  Speaker 1: disk becomes what astronomers call an active galactic nucleus, or AGN.
• 14:15
  Speaker 1: Some AGN are among the brightest objects in the observable universe,
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  Speaker 1: outshining every star in their host galaxy combined. But brightness
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  Speaker 1: is not the strangest part. As the disk churns, it
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  Speaker 1: generates powerful magnetic fields. These fields do not sit still.
• 14:34
  Speaker 1: They twist. They tighten. They thread through the innermost regions
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  Speaker 1: of the accretion disc and anchor themselves to the spinning
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  Speaker 1: black hole itself. This is where the ejection begins. A
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  Speaker 1: fraction of the infalling material does not make it into
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  Speaker 1: the black hole. The magnetic fields grab it and redirect it.
• 14:52
  Speaker 1: Instead of falling inward, this material gets flung outward along
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  Speaker 1: the magnetic field lines, launching away from the black hole
• 15:00
  Speaker 1: perpendicular to the disk, in two beams shooting in opposite directions.
• 15:05
  Speaker 1: One goes up, one goes down. These are the jets.
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  Speaker 1: The material inside those jets is plasma, not gas in
• 15:13
  Speaker 1: the ordinary sense. Plasma is what you get when matter
• 15:17
  Speaker 1: is heated so intensely that electrons are stripped away from
• 15:21
  Speaker 1: their atoms entirely. leaving behind a sea of charged particles.
• 15:26
  Speaker 1: The plasma in a black hole jet is threaded through
• 15:29
  Speaker 1: with those same magnetic fields that launched it, and as
• 15:33
  Speaker 1: the charged particles spiral along those field lines, they emit radiation.
• 15:39
  Speaker 1: This specific process is called synchrotron radiation. It produces radio
• 15:44
  Speaker 1: waves at the low frequencies that telescopes like LOFAR are
• 15:48
  Speaker 1: built to detect. It also produces the bluish visible glow
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  Speaker 1: you see in images of famous nearby jets. Every radio
• 15:56
  Speaker 1: map of Porphyrion is, in a sense, a map of
• 15:59
  Speaker 1: electrons spinning along magnetic field lines at near light speed
• 16:03
  Speaker 1: across 23 million light years of space. The ability to
• 16:08
  Speaker 1: detect synchrotron radiation means that astronomers can observe jets even
• 16:13
  Speaker 1: when they are completely invisible in ordinary light. This is
• 16:16
  Speaker 1: one of the great advantages of radio astronomy. Where optical
• 16:20
  Speaker 1: telescopes would see nothing but darkness punctuated by distant stars,
• 16:25
  Speaker 1: radio telescopes reveal the jets in stark detail, tracing their
• 16:30
  Speaker 1: paths across millions of light years. The jets from Centaurus A,
• 16:35
  Speaker 1: one of the nearest large radio galaxies, have been studied
• 16:39
  Speaker 1: in extensive detail for this reason. Centaurus A's jets extend
• 16:44
  Speaker 1: for about a million light years, and they have taught
• 16:47
  Speaker 1: astronomers much of what they know about jet structure and behavior.
• 16:51
  Speaker 1: When astronomers first began to catalog these radio sources, they
• 16:55
  Speaker 1: did not always know they were looking at jets. Some
• 16:58
  Speaker 1: of the brightest radio sources in the sky remained mysterious
• 17:03
  Speaker 1: for decades. It was only through careful observation and comparison
• 17:07
  Speaker 1: with optical data that astronomers pieced together the picture Distant
• 17:12
  Speaker 1: black holes were launching jets with enough energy to outshine
• 17:16
  Speaker 1: their entire host galaxies at radio wavelengths. The power flowing
• 17:21
  Speaker 1: through a single jet can be equivalent to the total
• 17:24
  Speaker 1: energy output of a million stars. This staggering output depends
• 17:29
  Speaker 1: on the black hole's mass and how quickly it is feeding.
• 17:32
  Speaker 1: A more massive black hole feeding rapidly produces more powerful jets.
• 17:37
  Speaker 1: But even smaller black holes can generate impressive jets under
• 17:41
  Speaker 1: the right circumstances. The jets leave the black hole traveling
• 17:45
  Speaker 1: at a significant fraction of the speed of light. In
• 17:49
  Speaker 1: nearby galaxies where we can observe jets in detail, the
• 17:53
  Speaker 1: plasma in some jets moves at more than 99% of
• 17:57
  Speaker 1: light speed. The energy involved is staggering. The jets are
• 18:01
  Speaker 1: not drifting. They are punching outward with extraordinary force. And
• 18:06
  Speaker 1: in an actively feeding black hole like the one that
• 18:09
  Speaker 1: produced Porphyrian, they maintain that force continuously as long as
• 18:14
  Speaker 1: the black hole keeps feeding. At small scales, all of
• 18:18
  Speaker 1: this is well understood. Astronomers have studied black hole jets
• 18:22
  Speaker 1: for decades. They have mapped them in nearby galaxies, measured
• 18:26
  Speaker 1: their speeds, amylised their radiation, mobbled the magnetic field structures
• 18:31
  Speaker 1: threading through them. Jets that stretch a few thousand light years,
• 18:36
  Speaker 1: or even a few hundred thousand light years, fit neatly
• 18:40
  Speaker 1: into the models. There are hundreds of known examples, and
• 18:44
  Speaker 1: the physics is worked out well enough that scientists can
• 18:47
  Speaker 1: predict what a jet should look like based on what
• 18:50
  Speaker 1: they know about its host black hole. The trouble begins
• 18:53
  Speaker 1: when the jets get very long. Picture a garden hose.
• 18:57
  Speaker 1: Hold it at arm's length and turn the water on.
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  Speaker 1: The stream comes out straight, coherent, predictable. Now imagine that
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  Speaker 1: same hose extending not a few feet, but all the
• 19:07
  Speaker 1: way to the horizon. The stream has to maintain its
• 19:10
  Speaker 1: structure across enormous distance, through varying pressures, through turbulence, across
• 19:16
  Speaker 1: whatever material it encounters along the way. Real jets face
• 19:20
  Speaker 1: an analogous problem. The farther a jet travels from the
• 19:24
  Speaker 1: black hole, the more opportunities it has to interact with
• 19:27
  Speaker 1: the surrounding intergalactic medium. The plasma is not moving through
• 19:32
  Speaker 1: empty space. It is moving through a thin but real
• 19:35
  Speaker 1: distribution of gas that fills the space between galaxies. Every
• 19:40
  Speaker 1: interaction is a chance for the jet to lose energy,
• 19:43
  Speaker 1: to slow, to wobble, to break apart. Most jets do
• 19:47
  Speaker 1: eventually fall apart. The ones we observe spanning hundreds of
• 19:51
  Speaker 1: thousands of light years are already impressive. The ones spanning
• 19:55
  Speaker 1: millions of light years are exceptional. At those distances, something
• 20:00
  Speaker 1: has to be holding the jet together. Some combination of
• 20:03
  Speaker 1: initial power, magnetic field stability, and favorable surrounding environment. For
• 20:09
  Speaker 1: a jet to reach 23 million light years, all of
• 20:12
  Speaker 1: those conditions had to hold, simultaneously, for an almost unimaginable
• 20:18
  Speaker 1: length of time. There is no agreed upon mechanism that
• 20:22
  Speaker 1: cleanly explains how jets survive to that scale. The magnetic
• 20:26
  Speaker 1: fields threading through the plasma provide some structural coherence, acting
• 20:31
  Speaker 1: something like a spine keeping the beam from dissolving into
• 20:35
  Speaker 1: the surrounding medium. The ram pressure of the jet itself
• 20:39
  Speaker 1: The sheer momentum of the plasma moving outward helps punch
• 20:43
  Speaker 1: through any resistance. But both of these effects weaken with distance.
• 20:48
  Speaker 1: Magnetic fields spread out. Momentum diffuses. The models that work
• 20:53
  Speaker 1: for jets spanning thousands of light years start straining badly
• 20:57
  Speaker 1: when applied to jets spanning millions. This is why Porphyrian
• 21:01
  Speaker 1: was not just a record breaker. It was a problem.
• 21:05
  Speaker 1: It was something the existing machinery of jet physics could
• 21:09
  Speaker 1: not straightforwardly account for. Astronomers did not lack a general
• 21:13
  Speaker 1: understanding of how jets form. What they lacked was a
• 21:17
  Speaker 1: clear picture of how anything stays coherent across 23 million
• 21:21
  Speaker 1: light years of intergalactic space. The question nobody had a
• 21:26
  Speaker 1: satisfying answer to was how a jet gets that big
• 21:29
  Speaker 1: without falling apart. The galaxy responsible for all of this
• 21:33
  Speaker 1: is not particularly impressive on its own. If you placed
• 21:37
  Speaker 1: it beside the Milky Way, you would notice it is larger, heavier,
• 21:41
  Speaker 1: more substantial. Roughly ten times the mass of our galaxy.
• 21:46
  Speaker 1: But in a universe full of galaxies numbering in the
• 21:48
  Speaker 1: hundreds of billions, ten times the Milky Way is not
• 21:52
  Speaker 1: a remarkable number. There are galaxies thousands of times more massive.
• 21:57
  Speaker 1: There are clusters that contain thousands of galaxies each. By
• 22:01
  Speaker 1: the standards of what exists out there, the host of
• 22:04
  Speaker 1: Porphyrian is a solid, hefty object, and not much more
• 22:08
  Speaker 1: than that. Its official designation is J152932. 16 plus 6001534 by 4,
• 22:19
  Speaker 1: not a name that rolls off the tongue. Astronomers confirmed
• 22:23
  Speaker 1: its identity using the W.M. Keck Observatory in Hawaii, matching
• 22:27
  Speaker 1: it to the radio structure that LOFAR had revealed and
• 22:31
  Speaker 1: pinning down its distance with spectroscopic measurements. That distance turned
• 22:35
  Speaker 1: out to be 7.5 billion light years from Earth. Write
• 22:39
  Speaker 1: that number down somewhere and look at it. 7.5 billion
• 22:44
  Speaker 1: light years. The observable universe stretches roughly 46 billion light
• 22:49
  Speaker 1: years in every direction from where we are standing. This
• 22:52
  Speaker 1: galaxy sits more than a sixth of the way to
• 22:55
  Speaker 1: the edge of everything we can see. It is not
• 22:58
  Speaker 1: in our neighborhood. It is not in our corner of
• 23:01
  Speaker 1: the cosmos. It is deep out there, in territory that
• 23:05
  Speaker 1: feels genuinely remote, even by the standards of extragalactic astronomy.
• 23:11
  Speaker 1: Now consider what 7.5 billion light years actually means in time.
• 23:17
  Speaker 1: Light travels at roughly 186,000 miles per second. It circles
• 23:19
  Speaker 1: the Earth more than seven times in a single second.
• 23:26
  Speaker 1: It crosses the distance from here to the Moon in
• 23:29
  Speaker 1: just over a second, and yet light leaving that galaxy 7.5
• 23:34
  Speaker 1: billion years ago has only just now reached us. The
• 23:38
  Speaker 1: photons landing in our telescopes tonight, the ones painting the
• 23:42
  Speaker 1: faint radio image of Porphyrion across our data, started their
• 23:47
  Speaker 1: journey before our Sun existed, before the Earth existed. The
• 23:51
  Speaker 1: solar system formed roughly 4.6 billion years ago, from a
• 23:56
  Speaker 1: collapsing cloud of gas and dust. When the light now
• 24:00
  Speaker 1: arriving from Porphyrion's host galaxy departed, none of that had
• 24:04
  Speaker 1: happened yet. There was no sun. There was no Earth.
• 24:09
  Speaker 1: The material that would eventually build our planet was still
• 24:12
  Speaker 1: scattered through space, unformed and waiting. Think about the other
• 24:16
  Speaker 1: galaxies we know about and the light that reaches us
• 24:19
  Speaker 1: from them. The nearby Andromeda Galaxy, our largest galactic neighbor,
• 24:24
  Speaker 1: sits only 2.5 million light years away. When we observe it,
• 24:29
  Speaker 1: we see it as it was before human beings existed
• 24:33
  Speaker 1: on Earth, before our species had even begun its evolutionary journey.
• 24:37
  Speaker 1: Yet Andromeda feels almost local compared to J152932. 16 plus 61534.4.
• 24:41
  Speaker 1: The vast majority of the galaxies we study lie somewhere
• 24:44
  Speaker 1: between these extremes. near enough to seem accessible through our instruments,
• 24:56
  Speaker 1: yet far enough to represent centuries, millions of years, or
• 25:00
  Speaker 1: billions of years into the past. This graduated collection of
• 25:04
  Speaker 1: temporal distances is what allows astronomers to piece together how
• 25:09
  Speaker 1: galaxies evolve over cosmic time. We are not looking at
• 25:13
  Speaker 1: a single moment in the universe's history, but rather a
• 25:17
  Speaker 1: three-dimensional map where distance and time become interchangeable measures. The
• 25:22
  Speaker 1: universe itself was roughly 6.3 billion years old when that
• 25:26
  Speaker 1: light left. The universe is currently about 13.8 billion years old.
• 25:32
  Speaker 1: So we are looking at this galaxy as it appeared
• 25:35
  Speaker 1: when the cosmos was less than half its present age.
• 25:38
  Speaker 1: The universe was younger then, smaller, denser. Galaxies were closer together.
• 25:45
  Speaker 1: The web of filaments connecting them was more compressed. The
• 25:49
  Speaker 1: whole structure of everything was tighter and more active than
• 25:52
  Speaker 1: it is today. Here is something worth sitting with. The
• 25:56
  Speaker 1: light you see from Betelgeuse tonight left that star around
• 25:59
  Speaker 1: the year 1376. Nights were still riding through Europe. That
• 26:05
  Speaker 1: light has spent over 600 years crossing space just to
• 26:09
  Speaker 1: reach your eye. Now multiply that feeling by about 12 million.
• 26:13
  Speaker 1: The light arriving from Porphyrian's host galaxy has been crossing
• 26:17
  Speaker 1: the universe for 7.5 billion years. Whatever that galaxy looks
• 26:22
  Speaker 1: like right now, whatever it is doing at this moment,
• 26:25
  Speaker 1: we have absolutely no way of knowing. We cannot know.
• 26:29
  Speaker 1: The information hasn't arrived yet. What we have is a snapshot.
• 26:35
  Speaker 1: A single image frozen in time from an era so
• 26:39
  Speaker 1: distant that the Earth did not exist to receive it.
• 26:43
  Speaker 1: That galaxy may have merged with another galaxy by now.
• 26:47
  Speaker 1: It may have been torn apart. The jets may have
• 26:50
  Speaker 1: shut down entirely. The black hole at its center may
• 26:53
  Speaker 1: have gone quiet. We are looking at the past, and
• 26:57
  Speaker 1: the past is all we will ever have access to.
• 27:00
  Speaker 1: This is one of the stranger features of astronomy that
• 27:03
  Speaker 1: rarely gets acknowledged directly. We do not observe the universe
• 27:07
  Speaker 1: as it is. We observe it as it was, at
• 27:10
  Speaker 1: varying depths of time depending on how far away each
• 27:14
  Speaker 1: object sits. Nearby stars we see as they were a
• 27:18
  Speaker 1: few years ago. The Andromeda galaxy we see as it
• 27:21
  Speaker 1: was about 2.5 million years ago. Porphyrian's host we see
• 27:26
  Speaker 1: as it was 7.5 billion years ago. The universe we
• 27:31
  Speaker 1: think we know is actually a layered collage of different moments,
• 27:35
  Speaker 1: all arriving at our instruments at the same time. none
• 27:39
  Speaker 1: of them current. So what do we actually see when
• 27:42
  Speaker 1: we look at this galaxy from 7.5 billion years in
• 27:45
  Speaker 1: the past? A reasonably large elliptical-type galaxy. Massive, but not extraordinary.
• 27:52
  Speaker 1: Perhaps 70 billion solar masses, give or take. That estimate
• 27:56
  Speaker 1: places it roughly 10 times heavier than the Milky Way.
• 27:59
  Speaker 1: It was the kind of galaxy that, in a catalogue
• 28:02
  Speaker 1: of millions of objects, would not make any list of
• 28:05
  Speaker 1: the most dramatic or unusual. No exceptional brightness, no unusual
• 28:10
  Speaker 1: shape that would flag it as something worth investigating. If
• 28:14
  Speaker 1: you stripped away the jets and looked only at the
• 28:16
  Speaker 1: galaxy itself, you might flip past it without pausing. That
• 28:21
  Speaker 1: is what makes this situation strange. The object producing Porphyrian
• 28:26
  Speaker 1: is not some colossal once-in-a-universe anomaly. It is a substantial galaxy, yes,
• 28:32
  Speaker 1: but not an outlier, not the biggest, not the brightest.
• 28:37
  Speaker 1: not sitting at the center of some rare supercluster with
• 28:40
  Speaker 1: exceptional resources. And yet, from somewhere inside it, a pair
• 28:45
  Speaker 1: of jets extended outward until they had crossed 23 million
• 28:49
  Speaker 1: light years of space. The scale of what came out
• 28:53
  Speaker 1: of that galaxy bears no obvious proportion to the galaxy itself.
• 28:58
  Speaker 1: That mismatch is part of what made the 2024 discovery
• 29:02
  Speaker 1: so difficult to immediately process. The product was far more
• 29:06
  Speaker 1: impressive than the factory producing it. At the centre of
• 29:10
  Speaker 1: that galaxy sat a supermassive black hole. That is not unusual.
• 29:15
  Speaker 1: Most large galaxies host supermassive black holes at their cores,
• 29:20
  Speaker 1: objects containing millions or billions of times the mass of
• 29:24
  Speaker 1: our Sun, compacted into a region smaller than our solar system.
• 29:29
  Speaker 1: The Milky Way has one. It is called Sagittarius A star.
• 29:33
  Speaker 1: and it weighs about 4 million solar masses. The black
• 29:37
  Speaker 1: hole at the center of J1529 plus 6001534Bot4 was apparently
• 29:46
  Speaker 1: far more active, fed by infalling material, channeling energy outward
• 29:51
  Speaker 1: through those jets at a rate that maintained their structure
• 29:54
  Speaker 1: across distances no jet had ever been measured to cross.
• 29:58
  Speaker 1: The galaxy was the setting. The black hole was the engine.
• 30:02
  Speaker 1: Everything that Porphyreon is, all 23 million light years of it,
• 30:07
  Speaker 1: traces back to whatever was feeding that single black hole
• 30:11
  Speaker 1: at the center of a galaxy we can no longer
• 30:13
  Speaker 1: see as it exists today. To understand what 23 million
• 30:17
  Speaker 1: light years actually means, you need to start somewhere familiar
• 30:22
  Speaker 1: and keep going until your sense of scale breaks. Start
• 30:26
  Speaker 1: with the Milky Way. Our galaxy is roughly 100,000 light
• 30:30
  Speaker 1: years across, from one edge to the other. That number
• 30:34
  Speaker 1: alone is staggering. Light moves at 186,000 miles per second.
• 30:40
  Speaker 1: It circles the Earth seven times in a single second.
• 30:44
  Speaker 1: And yet a beam of light crossing the Milky Way
• 30:47
  Speaker 1: from end to end would take 100,000 years to complete
• 30:51
  Speaker 1: the trip. The galaxy you live inside is so wide,
• 30:55
  Speaker 1: that light itself means longer than modern humans have existed
• 30:58
  Speaker 1: to cross it. Hold that number. 100,000 light years. That
• 31:04
  Speaker 1: is your starting unit. Porphyrian is 23 million light years across.
• 31:09
  Speaker 1: That is not 23 million compared to 100,000 in a
• 31:13
  Speaker 1: way that feels close. Do the division. Porphyrian is 230
• 31:18
  Speaker 1: times wider than the Milky Way. Some measurements put it
• 31:22
  Speaker 1: at 140 Milky Ways. depending on exactly where you draw
• 31:26
  Speaker 1: the outer boundary of the jet lobes. Either way, the
• 31:30
  Speaker 1: ratio is brutal. You could line up every star-forming disk,
• 31:34
  Speaker 1: every spiral arm, every dust lane of 140 galaxies identical
• 31:39
  Speaker 1: to our own, stretch them end to end in a
• 31:42
  Speaker 1: single unbroken chain, and you would still be looking at
• 31:46
  Speaker 1: something roughly the same size as Porphyrium. That chain of
• 31:49
  Speaker 1: galaxies would be Porphyrium. Now try a different comparison. The
• 31:54
  Speaker 1: nearest large galaxy to Earth is Andromeda. On a clear
• 31:58
  Speaker 1: dark night, you can actually see it with the naked eye,
• 32:02
  Speaker 1: a faint smear of light in the constellation of the
• 32:05
  Speaker 1: same name. Andromeda is 2.5 million light years away. That
• 32:10
  Speaker 1: distance feels cosmic. It is cosmic. Light leaving Andromeda right
• 32:15
  Speaker 1: now will not reach Earth for 2.5 million years. And
• 32:20
  Speaker 1: Porphyreon is nearly 10 times longer than that distance. You
• 32:24
  Speaker 1: could pack the full gap between the Milky Way and
• 32:27
  Speaker 1: Andromeda into Porphyrian's length ten times over and still have
• 32:32
  Speaker 1: room left. Here is one more. The Local Group is
• 32:36
  Speaker 1: the name astronomers give to the cluster of galaxies our
• 32:38
  Speaker 1: own Milky Way belongs to. It includes Andromeda, dozens of
• 32:43
  Speaker 1: smaller satellite galaxies, and everything else gravitationally bound to our neighbourhood.
• 32:48
  Speaker 1: The Local Group spans roughly 10 million light years. Porphyryon
• 32:53
  Speaker 1: is more than twice that. A single jet structure produced
• 32:57
  Speaker 1: by a single black hole is larger than the entire
• 33:00
  Speaker 1: gravitational family of galaxies that contains our home. Try the
• 33:04
  Speaker 1: scale model. Take the Milky Way and shrink it down
• 33:08
  Speaker 1: to the size of a dinner plate. A standard dinner
• 33:11
  Speaker 1: plate is about a foot across. At that scale, where
• 33:15
  Speaker 1: would Porphyryon end? Not across the table. Not across the room.
• 33:20
  Speaker 1: At that scale, Porphyrian would stretch approximately the length of
• 33:24
  Speaker 1: an American football field. You are standing at one end zone,
• 33:28
  Speaker 1: holding a dinner plate, and the far edge of Porphyrian
• 33:31
  Speaker 1: is in the other end zone, 100 yards away. The
• 33:35
  Speaker 1: dinner plate is your galaxy. The football field is the jet.
• 33:39
  Speaker 1: That comparison does something to a person if you sit
• 33:42
  Speaker 1: with it for a moment. The visceral quality matters. Abstract
• 33:46
  Speaker 1: numbers become concrete when translated into space you can walk.
• 33:50
  Speaker 1: The football field helps your mind grasp something that mathematics
• 33:54
  Speaker 1: alone cannot convey. Now bring in Centaurus A. If you
• 33:59
  Speaker 1: have spent any time looking at images from professional observatories,
• 34:03
  Speaker 1: you have probably seen Centaurus A without knowing its name.
• 34:07
  Speaker 1: It is one of the most photographed objects in the sky.
• 34:10
  Speaker 1: A massive elliptical galaxy with a dark dust lane cutting
• 34:14
  Speaker 1: across its middle, surrounded by enormous radio lobes. Centaurus A
• 34:20
  Speaker 1: is the closest active galactic nucleus to Earth, sitting about
• 34:24
  Speaker 1: 13 million light years away. Its jet system is famous
• 34:28
  Speaker 1: precisely because of how large it is. Those jets span
• 34:32
  Speaker 1: roughly 10 Milky Ways. Astronomers have studied Centaurus A for decades,
• 34:37
  Speaker 1: partly because at that scale, the structure is detailed enough
• 34:41
  Speaker 1: to examine closely. Porphyrian is 14 times larger than Centaurus A,
• 34:46
  Speaker 1: not slightly bigger. not a new record by a comfortable margin,
• 34:51
  Speaker 1: 14 times. That multiplier is not merely incremental. It places
• 34:57
  Speaker 1: Porphyreon in an entirely different category of cosmic object, operating
• 35:02
  Speaker 1: according to principles that existing theory had not adequately described.
• 35:07
  Speaker 1: Whatever made Centaurus A one of the most studied and
• 35:11
  Speaker 1: visually dramatic objects in the night sky, Porphyreon did that
• 35:15
  Speaker 1: and then kept going for another 13 times the same distance.
• 35:20
  Speaker 1: The nearest famous giant jet system we have, the one
• 35:23
  Speaker 1: close enough for us to study in detail, is a
• 35:26
  Speaker 1: fraction of what Porphyrian achieved. Why does this matter beyond
• 35:30
  Speaker 1: the spectacle of it? Because there are physical limits on
• 35:34
  Speaker 1: how big jets are supposed to get. As a jet
• 35:37
  Speaker 1: travels outward from its source, it is pushing through material,
• 35:41
  Speaker 1: not empty space exactly. but the diffuse gas that fills
• 35:45
  Speaker 1: the space between galaxies. Every light year of progress takes energy.
• 35:51
  Speaker 1: The jet is constantly being slowed, scattered, disrupted by the
• 35:55
  Speaker 1: medium it is moving through. At some point, the models say,
• 35:59
  Speaker 1: the energy runs out. The jet disperses. The lobes break
• 36:03
  Speaker 1: apart and fade. The structure loses coherence. There is a ceiling.
• 36:08
  Speaker 1: Porphyrion is through the ceilings. At 23 million light years,
• 36:13
  Speaker 1: this jet is operating in a regime where the standard
• 36:15
  Speaker 1: models of jet propagation simply did not predict anything should
• 36:19
  Speaker 1: survive intact. This is not a minor violation. The theoretical
• 36:24
  Speaker 1: models were built on observations of structures far smaller, making
• 36:28
  Speaker 1: Porphyrion's coherence a profound challenge to existing understanding. The gas
• 36:33
  Speaker 1: between galaxies becomes increasingly tenuous as you move away from
• 36:37
  Speaker 1: clusters and into the voids between superclusters. In one sense,
• 36:42
  Speaker 1: this helps. Less resistance means the jet can travel farther.
• 36:46
  Speaker 1: But even in near emptiness, a jet has to maintain
• 36:50
  Speaker 1: its structure. The magnetic fields threading through the plasma have
• 36:54
  Speaker 1: to hold their alignment across distances that dwarf anything astronomers
• 36:58
  Speaker 1: had previously measured. The energy pouring from the black hole
• 37:02
  Speaker 1: has to be consistent enough and sustained for long enough
• 37:06
  Speaker 1: that the jets do not simply collapse before they reach
• 37:09
  Speaker 1: full extension. Whatever Porphyrian's host black hole was doing, it
• 37:14
  Speaker 1: did it long enough and hard enough to push plasma
• 37:17
  Speaker 1: across 23 million light years and leave coherent lobes at
• 37:21
  Speaker 1: the far end. Those lobes, bright at their edges, are
• 37:25
  Speaker 1: the evidence. They are not faint smears. They are structured, definable,
• 37:31
  Speaker 1: with the hotspot morphology that marks an active, powerful jet system.
• 37:36
  Speaker 1: The coherence of those structures is what matters most. A
• 37:40
  Speaker 1: diffuse blob at this distance could be dismissed as noise
• 37:43
  Speaker 1: or coincidence. But defined lobes with distinct hotspots indicate real
• 37:48
  Speaker 1: physics operating at an unimaginable scale. The jet made it.
• 37:53
  Speaker 1: All the way out there, it made it. There is
• 37:56
  Speaker 1: something almost defiant about this. The universe imposes constraints. Objects
• 38:01
  Speaker 1: operating at the edge of those constraints are interesting precisely
• 38:05
  Speaker 1: because they reveal where the physics gets complicated. A jet
• 38:09
  Speaker 1: half this size would be remarkable. A jet twice as
• 38:12
  Speaker 1: large as any previous record would prompt serious investigation. Porphyrian
• 38:18
  Speaker 1: is 40% larger than the previous record holder, which itself
• 38:22
  Speaker 1: had shattered the record before that. Each time the outer
• 38:26
  Speaker 1: boundary of what jets can do gets extended, the theoretical
• 38:30
  Speaker 1: models have to stretch to accommodate the new reality. At
• 38:34
  Speaker 1: 23 million light years, the models do not just stretch.
• 38:38
  Speaker 1: They have to be rethought. You are not looking at
• 38:41
  Speaker 1: an exception at the edge of a known distribution. You
• 38:45
  Speaker 1: may be looking at a category of object that existing
• 38:48
  Speaker 1: theory had not properly accounted for. The same way Betelgeuse's
• 38:52
  Speaker 1: dimming turned out to be a clue about something deeper
• 38:55
  Speaker 1: happening in how the most powerful black holes interact with
• 38:58
  Speaker 1: the structure of the universe around them. The size is
• 39:01
  Speaker 1: not the end of the story. It is the question
• 39:04
  Speaker 1: the story is trying to answer. Nothing produced by a
• 39:08
  Speaker 1: single galaxy has ever been measured at this size, and
• 39:11
  Speaker 1: that by itself is enough to demand an explanation. Not
• 39:15
  Speaker 1: all black hole jets look the same, and the differences
• 39:18
  Speaker 1: are not cosmetic. When astronomers began cataloguing radio galaxies in
• 39:23
  Speaker 1: serious numbers during the mid-20th century, they noticed a pattern.
• 39:29
  Speaker 1: Some jets fade as they extended outward. Others grew brighter
• 39:33
  Speaker 1: toward their ends. This was not random. The shape of
• 39:37
  Speaker 1: the emission was telling them something about the physics happening inside.
• 39:41
  Speaker 1: A structure that brightens at its tips behaves differently from
• 39:44
  Speaker 1: one that dims at its tips. That difference has meanings.
• 39:49
  Speaker 1: and astronomers eventually built a system around it. In 1974,
• 39:54
  Speaker 1: two British astronomers named Bernard Phaneroff and Julia Riley sat
• 39:59
  Speaker 1: down with a catalogue of radio galaxies and sorted them
• 40:03
  Speaker 1: by morphology. What they found was clean enough to name.
• 40:07
  Speaker 1: There were two distinct families. The first had its brightest
• 40:11
  Speaker 1: emission concentrated near the centre, close to the core, with
• 40:15
  Speaker 1: the outer edges fading gradually into the surrounding medium. The
• 40:20
  Speaker 1: second family was the opposite. Its outer lobes were the
• 40:23
  Speaker 1: brightest parts of the entire structure, with sharp, concentrated knots
• 40:28
  Speaker 1: of emission sitting at the very tips. Phaneroff and Riley
• 40:32
  Speaker 1: called these two groups Class I and Class II. Astronomers
• 40:36
  Speaker 1: still call them FRI and FRII today, 50 years later,
• 40:41
  Speaker 1: because the distinction has held up under every test since.
• 40:44
  Speaker 1: The difference sounds like a bookkeeping detail. It is not.
• 40:49
  Speaker 1: What the shape tells you is how much power the
• 40:51
  Speaker 1: jet is carrying, and whether that power is enough to
• 40:54
  Speaker 1: punch through the material surrounding the galaxy. Fry jets are
• 40:59
  Speaker 1: the quieter ones. They launch from the black hole with
• 41:02
  Speaker 1: real energy. But as they travel outward, they slow down.
• 41:06
  Speaker 1: They mix with the surrounding gas. They lose coherence. The
• 41:11
  Speaker 1: brightness fades toward the edges because the jet is losing
• 41:14
  Speaker 1: the fight against the medium it is moving through. Picture
• 41:18
  Speaker 1: a garden sprinkler. Water fans outward in a soft arc,
• 41:22
  Speaker 1: spreads wide, and falls without hitting anything hard. The energy dissipates.
• 41:27
  Speaker 1: The pressure drops. Nothing at the edge is pushing back
• 41:31
  Speaker 1: because nothing is moving fast enough to reach it. FRII
• 41:35
  Speaker 1: jets are different. They carry enough power to stay coherent
• 41:39
  Speaker 1: over enormous distances. They drive through surrounding gas rather than
• 41:44
  Speaker 1: blending with it. The jet maintains its structure, pushes outward,
• 41:48
  Speaker 1: and eventually slams into the diffuse material at the far
• 41:52
  Speaker 1: edge of its reach. That collision is where the energy concentrates.
• 41:56
  Speaker 1: Particles pile up, magnetic fields compress, and the emission spikes.
• 42:02
  Speaker 1: Those spikes are the hotspots. They are the brightest features
• 42:05
  Speaker 1: of the entire system. sitting at the outer tips of
• 42:08
  Speaker 1: the lobes like two lit fists at the ends of
• 42:11
  Speaker 1: two very long arms. Think of a fire hose instead
• 42:15
  Speaker 1: of a sprinkler. The pressure stays high all the way
• 42:18
  Speaker 1: to the end, and when the water hits something solid,
• 42:21
  Speaker 1: it hits hard. This morphological difference maps directly onto a
• 42:25
  Speaker 1: difference in power. FRII galaxies are systematically more luminous in
• 42:30
  Speaker 1: radio wavelengths than FRII galaxies. Their jets are not just longer,
• 42:36
  Speaker 1: They are more energetic per unit length. They drive shock
• 42:40
  Speaker 1: waves into surrounding material at distances where fry jets would
• 42:44
  Speaker 1: have dissolved long ago. The boundary between the two classes
• 42:48
  Speaker 1: is not perfectly sharp, and some objects sit in between,
• 42:52
  Speaker 1: but the core distinction holds across thousands of catalogued systems.
• 42:57
  Speaker 1: Shape predicts power. Power predicts reach. An astronomer looking at
• 43:02
  Speaker 1: a radio image of an unfamiliar galaxy can read the
• 43:06
  Speaker 1: morphology the way a geologist reads rock strata. The structure
• 43:10
  Speaker 1: carries its history inside it. Over the decades since Fanaroff
• 43:15
  Speaker 1: and Reilly's original work, this classification scheme has become foundational
• 43:19
  Speaker 1: to how astronomers interpret large-scale cosmic structure and evolution. The
• 43:25
  Speaker 1: distinction between FRI and FRII objects reveals not merely morphology,
• 43:31
  Speaker 1: but fundamental physics of jet production and propagation through intergalactic space.
• 43:37
  Speaker 1: Astronomers discovered that FRII objects tend to inhabit more massive
• 43:42
  Speaker 1: galaxies with denser central environments, suggesting a direct connection between
• 43:48
  Speaker 1: jet power and host galaxy properties. This relationship has enabled
• 43:52
  Speaker 1: researchers to use radiomorphology as a diagnostic tool for understanding
• 43:58
  Speaker 1: both the black holes themselves and the broader cosmological contexts
• 44:02
  Speaker 1: in which they operate. The FRI to FRII classification has
• 44:07
  Speaker 1: thus evolved into one of extragalactic astronomy's most powerful and
• 44:12
  Speaker 1: enduring interpretive frameworks. Porphyrian is an FRI, emphatically. Its outer
• 44:19
  Speaker 1: lobes span 7 megaparsecs, which is 23 million light years,
• 44:25
  Speaker 1: and at the tips of those lobes sit the characteristic
• 44:27
  Speaker 1: bright hotspots of an edge-brightened system. When you look at
• 44:32
  Speaker 1: a radio image of Porphyrian, the center is relatively dim.
• 44:36
  Speaker 1: The power signature sits at the edges, 11.5 million light
• 44:40
  Speaker 1: years out from the core in each direction. where the
• 44:43
  Speaker 1: jets have spent an enormous stretch of cosmic time driving
• 44:47
  Speaker 1: through whatever lay in their path. That morphology is not
• 44:51
  Speaker 1: just a shape on a map. It is a statement
• 44:53
  Speaker 1: about what the black hole at the centre has been doing,
• 44:56
  Speaker 1: how hard it has been running, and for how long.
• 45:00
  Speaker 1: Classification systems like this exist for a reason. In astronomy,
• 45:05
  Speaker 1: you often cannot directly measure what you want to know.
• 45:08
  Speaker 1: You cannot fly out to a black hole and weigh
• 45:11
  Speaker 1: it or time it or watch it operate. What you
• 45:14
  Speaker 1: can do is measure the signature it leaves on the
• 45:17
  Speaker 1: material around it. The shape of a radio galaxy is
• 45:21
  Speaker 1: one of those signatures. An edge-brightened morphology with prominent hotspots
• 45:26
  Speaker 1: tells you the central engine was powerful enough to drive
• 45:30
  Speaker 1: a coherent jet across cosmological distances without losing the fight
• 45:35
  Speaker 1: to the surrounding medium. It is the radio equivalent of
• 45:38
  Speaker 1: a footprint. You see the shape and you know something
• 45:42
  Speaker 1: about what left it, even if the thing itself is 7.5
• 45:46
  Speaker 1: billion light years away and looks like nothing to the
• 45:49
  Speaker 1: naked eye. There is also a relationship between FII morphology
• 45:54
  Speaker 1: and environment. High-powered jets punch into the material around them,
• 46:00
  Speaker 1: but they also inflate enormous lobes of diffuse plasma that
• 46:04
  Speaker 1: spread outward from the hotspots. These lobes push back against
• 46:08
  Speaker 1: surrounding gas. They heat it. They displace it. The jet
• 46:12
  Speaker 1: builds its own cocoon of shocked material around itself as
• 46:16
  Speaker 1: it travels. At the scale of a system like Porphyrian,
• 46:20
  Speaker 1: that cocoon is not a small thing. It represents a
• 46:23
  Speaker 1: colossal volume of gas that the jet has physically moved, heated,
• 46:28
  Speaker 1: and rearranged across hundreds of millions of years. The shape
• 46:32
  Speaker 1: of the system, Those two edge-brightened lobes stretching in opposite
• 46:37
  Speaker 1: directions is the record of all that work preserved in
• 46:40
  Speaker 1: the radio spectrum. What makes Porphyrium remarkable, even among FII systems,
• 46:47
  Speaker 1: is not just the size, but what the size implies
• 46:50
  Speaker 1: about maintaining power across time. A jet of 7 megaparsecs
• 46:55
  Speaker 1: did not appear quickly. It required a continuous output sustained
• 46:59
  Speaker 1: across time scales that are difficult to hold in the mind.
• 47:03
  Speaker 1: At every stage of that journey, the jet had to
• 47:06
  Speaker 1: stay focused, stay energetic, and keep driving. The FII morphology
• 47:12
  Speaker 1: says it succeeded. The lobes are extended. The hotspots are bright.
• 47:17
  Speaker 1: The structure is intact. Whatever was powering the black hole
• 47:21
  Speaker 1: at the center of that host galaxy ran hard and
• 47:23
  Speaker 1: ran long, and the edge-brightened signature stretched across 23 million
• 47:28
  Speaker 1: light years is the direct evidence of that sustained campaign.
• 47:33
  Speaker 1: The hotspots at Peripherion's outer edges are where the jets
• 47:37
  Speaker 1: finally met resistance after travelling farther than any jet had
• 47:41
  Speaker 1: ever travelled before. The discovery did not come from a
• 47:45
  Speaker 1: single dramatic moment at a single telescope. There was no
• 47:49
  Speaker 1: night when an astronomer looked up from a screen and gasped.
• 47:53
  Speaker 1: No single instrument swung toward the right patch of sky
• 47:56
  Speaker 1: and caught something no one had ever seen. What found
• 47:59
  Speaker 1: Peripherion was something slower, stranger. and in its own way
• 48:03
  Speaker 1: more impressive than that. It was a map, the largest
• 48:07
  Speaker 1: and most detailed radio map of the universe ever assembled,
• 48:11
  Speaker 1: and Perferion had been hiding inside it the whole time.
• 48:15
  Speaker 1: To understand how that map got made, you need to
• 48:18
  Speaker 1: understand what LOFAR actually is. Most people, when they imagine
• 48:23
  Speaker 1: a radio telescope, picture a single enormous dish, something like
• 48:28
  Speaker 1: the Arecibo Observatory in Puerto Rico, a concrete bowl carved
• 48:33
  Speaker 1: into a hillside, or the Fast Telescope in China, 500
• 48:37
  Speaker 1: meters across and visible from space. Those instruments are real,
• 48:42
  Speaker 1: and they are remarkable. LOFAR is nothing like them. There
• 48:46
  Speaker 1: is no dish. There is no bowl. There is no
• 48:49
  Speaker 1: single structure you could point at and say, that is
• 48:52
  Speaker 1: the telescope. LOFAR is a network. Its full name is
• 48:57
  Speaker 1: the Low Frequency Array. and it is built from thousands
• 49:00
  Speaker 1: of small, simple antennas spread across the Netherlands and into
• 49:04
  Speaker 1: neighbouring countries in Europe. Each individual antenna looks almost unremarkable,
• 49:10
  Speaker 1: a set of crossed dipoles, low to the ground, not
• 49:13
  Speaker 1: much taller than a person. The kind of thing you
• 49:16
  Speaker 1: might mistake for an art installation or an abandoned science
• 49:20
  Speaker 1: fair project but the antennas do not work alone they
• 49:25
  Speaker 1: work together and the way they work together is what
• 49:28
  Speaker 1: makes lo far extraordinary the technique is called interferometry by
• 49:33
  Speaker 1: combining signals from antennas spread across hundreds of kilometers LOFAR
• 49:39
  Speaker 1: effectively behaves like a single telescope, as wide as the
• 49:43
  Speaker 1: entire baseline between its outermost stations. The signals from each
• 49:47
  Speaker 1: antenna are timestamped precisely and sent to a central processor,
• 49:52
  Speaker 1: where they are combined mathematically. Differences in the arrival time
• 49:57
  Speaker 1: of radio waves at different stations encode information about where
• 50:01
  Speaker 1: in the sky those waves came from. The wider the network,
• 50:05
  Speaker 1: the finer the resolution. LOFAR's baseline stretches across much of
• 50:10
  Speaker 1: northwestern Europe, giving it an effective aperture that no single
• 50:14
  Speaker 1: dish could approach at these frequencies. And the frequencies matter
• 50:19
  Speaker 1: enormously here. LOFAR operates between roughly 10 and 240 megahertz.
• 50:26
  Speaker 1: These are very low frequencies by the standards of radio astronomy,
• 50:30
  Speaker 1: corresponding to wavelengths between about 1 meter and 30 meters.
• 50:35
  Speaker 1: Most major radio telescopes operate at higher frequencies, where the
• 50:39
  Speaker 1: sky is less cluttered with interference and many well-studied objects
• 50:43
  Speaker 1: shine more brightly. The problem is that the extended lobes
• 50:47
  Speaker 1: of black hole jets glow most intensely at low frequencies.
• 50:51
  Speaker 1: This is a consequence of the physics inside the jets themselves.
• 50:55
  Speaker 1: The electrons spiralling through the magnetic fields of a jet
• 50:59
  Speaker 1: lose energy over time. The highest energy electrons fade first.
• 51:04
  Speaker 1: What remains in an old or diffuse jet structure is
• 51:08
  Speaker 1: a population of lower energy electrons emitting at longer wavelengths,
• 51:13
  Speaker 1: lower frequencies. Previous radio telescopes, tuned to higher frequencies, were
• 51:19
  Speaker 1: functionally blind to these faint, extended structures. The lobes were there.
• 51:25
  Speaker 1: The signal was real. The instruments just could not hear it.
• 51:29
  Speaker 1: LOFAR was designed specifically to operate where other telescopes could not.
• 51:34
  Speaker 1: Its sensitivity at low frequencies is not a side feature.
• 51:38
  Speaker 1: It is the point. When its survey teams began scanning
• 51:41
  Speaker 1: the sky, they were looking at a part of the
• 51:44
  Speaker 1: spectrum that had been largely unexplored at this level of
• 51:47
  Speaker 1: resolution and depth. The structures that turned up were, in
• 51:51
  Speaker 1: some cases, unlike anything catalogued before. The survey that found
• 51:56
  Speaker 1: Porphyrian is called LO-TSS. The LOFAR 2-meter sky survey. The
• 52:03
  Speaker 1: 2 meter refers to the approximate wavelength at the survey's
• 52:06
  Speaker 1: core frequency. Over years of observing, LowTSS compiled data across
• 52:12
  Speaker 1: a significant portion of the northern sky, cataloguing radio sources
• 52:17
  Speaker 1: with a sensitivity and resolution that no previous low-frequency survey
• 52:22
  Speaker 1: had matched. When the results were processed, the catalogue contained 13.7
• 52:26
  Speaker 1: million individual radio sources. 13.7 million. galaxies, jets, supernovae remnants, pulsars,
• 52:37
  Speaker 1: and structures that did not fit neatly into any existing category.
• 52:41
  Speaker 1: It was the most detailed radio picture of the universe
• 52:44
  Speaker 1: ever produced. Porphyrian was one entry among those millions, finding
• 52:49
  Speaker 1: it was not obvious. A structure spanning 23 million light years,
• 52:55
  Speaker 1: seen from 7.5 billion light years away, subtends a certain
• 53:00
  Speaker 1: angle on the sky. That angle is large enough to
• 53:03
  Speaker 1: be noticed, but identifying it as a single coherent object
• 53:07
  Speaker 1: rather than several unrelated sources requires careful analysis. The team
• 53:13
  Speaker 1: working with the LAO-TSS data had to distinguish Porphyrion's two
• 53:17
  Speaker 1: giant lobes from the background noise of millions of other
• 53:21
  Speaker 1: radio emitters. They had to establish that both lobes belong
• 53:25
  Speaker 1: to the same object, and then they had to figure
• 53:28
  Speaker 1: out what that object actually was. meaning they had to
• 53:31
  Speaker 1: find the galaxy at the center responsible for producing the jets.
• 53:36
  Speaker 1: That is where the other telescopes came in. LOFAR could
• 53:39
  Speaker 1: see the radio emission from the lobes, but pinpointing a
• 53:43
  Speaker 1: host galaxy requires data at other wavelengths. The team turned
• 53:47
  Speaker 1: to the Giant Metrowave Radio Telescope in India, known as
• 53:51
  Speaker 1: the GMRT. The GMRT operates at higher radio frequencies than
• 53:56
  Speaker 1: LOFAR's survey band, giving complementary data on the jet structure
• 54:01
  Speaker 1: and helping to confirm that what LOFAR had detected was
• 54:04
  Speaker 1: a genuine extended source rather than an artifact. Together, LOFAR
• 54:09
  Speaker 1: and the GMRT gave the team a more complete picture
• 54:12
  Speaker 1: of the radio morphology. For the optical side, they used
• 54:16
  Speaker 1: data from DESI, the Dark Energy Spectroscopic Instrument. DESI is
• 54:21
  Speaker 1: a survey instrument mounted on a telescope at the Kitt
• 54:24
  Speaker 1: Peak National Observatory in Arizona. designed to map the large-scale
• 54:29
  Speaker 1: structure of the universe by measuring the redshifts of tens
• 54:32
  Speaker 1: of millions of galaxies. Its dataset contains detailed optical information
• 54:38
  Speaker 1: about enormous numbers of objects across the sky, and it
• 54:42
  Speaker 1: provided a candidate for the host galaxy sitting between Porphyrian's
• 54:46
  Speaker 1: two lobes. Identifying a candidate, though, is not the same
• 54:51
  Speaker 1: as confirming it. Confirmation required a spectrum, That spectrum came
• 54:56
  Speaker 1: from the W.M. Keck Observatory in Hawaii, one of the
• 54:59
  Speaker 1: most powerful optical telescopes on Earth. Keck's instruments can take
• 55:04
  Speaker 1: the light from a faint, distant galaxy and spread it
• 55:07
  Speaker 1: into its component wavelengths with enough precision to measure the
• 55:11
  Speaker 1: redshift directly. Redshift is the stretching of light as it
• 55:15
  Speaker 1: travels across an expanding universe, and measuring it tells you
• 55:19
  Speaker 1: how far away something is. The Keck observation placed the
• 55:23
  Speaker 1: host galaxy at a redshift corresponding to a distance of 7.5
• 55:28
  Speaker 1: billion light years. It locked in the distance. Without that measurement,
• 55:33
  Speaker 1: everything else was uncertain. With it, the team could calculate
• 55:36
  Speaker 1: the true physical scale of what LOFAR had found. No
• 55:40
  Speaker 1: single instrument in this chain could have completed the picture alone.
• 55:45
  Speaker 1: LOFAR had the low frequency sensitivity to detect the lobes.
• 55:49
  Speaker 1: The GMRT sharpened the radio picture. DESY pointed toward the
• 55:54
  Speaker 1: host galaxy. KEK confirmed the distance. Each step depended on
• 55:58
  Speaker 1: the previous one. Take any piece away and the discovery
• 56:02
  Speaker 1: either fails entirely or remains inconclusive. This is increasingly how
• 56:07
  Speaker 1: astronomy works at the frontier. Not one telescope pointing at
• 56:12
  Speaker 1: one object, but a coordinated sequence of instruments. each contributing
• 56:16
  Speaker 1: what it does best, each handing off to the next.
• 56:20
  Speaker 1: The structure had been sitting in the data the whole time,
• 56:23
  Speaker 1: waiting for someone to ask the right question in the
• 56:26
  Speaker 1: right part of the spectrum. The jets of Porphyrion are
• 56:29
  Speaker 1: not made of anything exotic, which makes their scale even
• 56:33
  Speaker 1: harder to explain. There is no mysterious substance here, no
• 56:37
  Speaker 1: unknown particle. The material inside those jets is plasma. the
• 56:42
  Speaker 1: same state of matter that fills the interior of stars,
• 56:46
  Speaker 1: the same thing that flickers inside a neon sign, just
• 56:49
  Speaker 1: taken to an extreme that the word extreme does not
• 56:53
  Speaker 1: adequately cover. To understand what plasma is, start with a
• 56:57
  Speaker 1: normal atom. A nucleus surrounded by electrons, orbiting at specific distances,
• 57:04
  Speaker 1: held there by electrical attraction. Heat that atom enough, and
• 57:09
  Speaker 1: the electrons get knocked loose. The atom stops being a
• 57:12
  Speaker 1: neutral particle and becomes a charged one. The electrons fly free.
• 57:18
  Speaker 1: What you have left is a soup of positively charged
• 57:20
  Speaker 1: nuclei and negatively charged electrons, no longer bound to each other,
• 57:26
  Speaker 1: responsive to magnetic fields in ways that neutral matter is not.
• 57:31
  Speaker 1: That is plasma. And that is what porphyrion is made of,
• 57:35
  Speaker 1: from one end to the other, across 23 million light years.
• 57:39
  Speaker 1: The plasma inside the jets is not drifting, it is
• 57:43
  Speaker 1: moving at speeds close to the speed of light, fractions
• 57:47
  Speaker 1: of a percent below the universal speed limit. At those velocities,
• 57:52
  Speaker 1: the particles carry enormous kinetic energy, and they do not
• 57:56
  Speaker 1: travel in straight lines through the jet, they spiral. Magnetic
• 58:00
  Speaker 1: field lines thread through the entire length of the structure,
• 58:04
  Speaker 1: twisting through the jet like a coiled spring running from
• 58:07
  Speaker 1: one end to the other. Charged particles moving through a
• 58:11
  Speaker 1: magnetic field do not cut across those field lines freely,
• 58:15
  Speaker 1: they wrap around them. An electron caught in a magnetic
• 58:18
  Speaker 1: field spirals along it in tight loops, following the field
• 58:22
  Speaker 1: line wherever it goes. In Porphyreon, those field lines run
• 58:27
  Speaker 1: for millions of light years, and the electrons follow them
• 58:30
  Speaker 1: the entire way. Here is where the physics produces something detectable.
• 58:35
  Speaker 1: When a charged particle spirals along the magnetic field line,
• 58:39
  Speaker 1: it accelerates. Accelerating charges emit radiation. The specific kind of
• 58:46
  Speaker 1: radiation produced by relativistic electrons spiraling through a magnetic field
• 58:51
  Speaker 1: has a name, synchrotron radiation. It covers a broad spectrum,
• 58:56
  Speaker 1: from radio waves up through visible light, and the frequency
• 59:00
  Speaker 1: of the emission depends on the strength of the magnetic
• 59:03
  Speaker 1: field and the energy of the electrons. In visible light,
• 59:07
  Speaker 1: synchrotron radiation from jets produces a characteristic bluish glow. In
• 59:12
  Speaker 1: the radio part of the spectrum, it produces the low
• 59:15
  Speaker 1: frequency emissions that LOFAR was built to detect. Every radio
• 59:20
  Speaker 1: map of Porphyryon is, in the most literal sense, a
• 59:23
  Speaker 1: map of electrons spiraling along magnetic field lines. The light
• 59:28
  Speaker 1: reaching those antenna arrays in the Netherlands is the direct
• 59:32
  Speaker 1: physical product of charged particles corkscrewing through a magnetic structure 7.5
• 59:39
  Speaker 1: billion light years away. The energy required to maintain this
• 59:43
  Speaker 1: across 23 million light years is not easy to put
• 59:47
  Speaker 1: into ordinary terms. A single cubic meter of plasma moving
• 59:51
  Speaker 1: at near light speed along the magnetic field line carries
• 59:55
  Speaker 1: a tremendous amount of energy. Multiply that by the volume
• 59:59
  Speaker 1: of a structure 23 million light years long, and wide
• 1:00:03
  Speaker 1: enough to register on radio maps, and the total energy
• 1:00:06
  Speaker 1: content becomes a number that loses all intuitive meaning. Researchers
• 1:00:11
  Speaker 1: working on jet energetics have to use units borrowed from
• 1:00:14
  Speaker 1: cosmology just to write it down without the exponent becoming absurd.
• 1:00:19
  Speaker 1: The power output of Porphyrian's jets has been estimated at
• 1:00:23
  Speaker 1: the equivalent of several trillion suns, running continuously. Not for
• 1:00:28
  Speaker 1: a day, not for a year, for what must have
• 1:00:31
  Speaker 1: been hundreds of millions of years at minimum to have
• 1:00:34
  Speaker 1: built something this long. The problem with this picture is
• 1:00:38
  Speaker 1: that plasma, at large scales, wants to come apart. Jets
• 1:00:42
  Speaker 1: are not stable by default. The plasma inside a jet
• 1:00:46
  Speaker 1: is subject to instabilities that are well understood in the
• 1:00:49
  Speaker 1: physics of magnetohydrodynamics, which is the field concerned with how
• 1:00:53
  Speaker 1: magnetic fields and conducting fluids like plasma interact. Kelvin-Helmholtz instability
• 1:00:59
  Speaker 1: occurs at the boundary between the fast-moving jet and the
• 1:01:03
  Speaker 1: slower material outside it. The shearing between those two regions
• 1:01:08
  Speaker 1: generates ripples, and those ripples can grow into large-scale disruptions
• 1:01:13
  Speaker 1: but shred the jet apart. Kink instability occurs when the
• 1:01:17
  Speaker 1: magnetic field threading through the jet gets bent, and the
• 1:01:21
  Speaker 1: bending amplifies itself, twisting the jet until it loses coherence.
• 1:01:27
  Speaker 1: These are not theoretical edge cases. They're real processes that
• 1:01:31
  Speaker 1: have been observed in jets far smaller than Porphyrion. Most
• 1:01:35
  Speaker 1: jets do not survive them at large scales. Most jets
• 1:01:39
  Speaker 1: dissipate their energy, spread out, and stop being jets long
• 1:01:44
  Speaker 1: before they cover anything close to a megaparsec. Porphyrion covers
• 1:01:48
  Speaker 1: 7 megaparsecs. It did not dissipate. something kept it coherent
• 1:01:54
  Speaker 1: across a distance where every known instability should have torn
• 1:01:58
  Speaker 1: it apart. The answer, as far as researchers can determine,
• 1:02:02
  Speaker 1: lies in the magnetic field itself. A jet threaded by
• 1:02:06
  Speaker 1: a strong, well-ordered magnetic field is more resistant to these
• 1:02:10
  Speaker 1: instabilities than one with a weaker or more tangled field structure.
• 1:02:15
  Speaker 1: The magnetic field acts as a kind of internal scaffolding.
• 1:02:19
  Speaker 1: It suppresses the growth of the kink instability, by providing
• 1:02:22
  Speaker 1: a restoring force that pulls the jet back toward alignment
• 1:02:26
  Speaker 1: when it starts to bend. It controls the boundary mixing
• 1:02:29
  Speaker 1: at the edges of the jet by organizing the plasma
• 1:02:32
  Speaker 1: in a way that resists shearing. The magnetic field is,
• 1:02:36
  Speaker 1: in the simplest terms, what holds a jet together. This
• 1:02:40
  Speaker 1: is not controversial. What is not understood is how Porphyrian
• 1:02:44
  Speaker 1: maintained a sufficiently strong and ordered magnetic field across this
• 1:02:49
  Speaker 1: specific scale and over this specific time scale. Magnetic fields
• 1:02:54
  Speaker 1: in plasma are not static. They evolve. They reconnect. They
• 1:02:59
  Speaker 1: get tangled by turbulence. Keeping a magnetic field coherent over
• 1:03:04
  Speaker 1: millions of light years of jet is not simply a
• 1:03:07
  Speaker 1: matter of switching it on at the source and watching
• 1:03:10
  Speaker 1: it hold. The field has to be continuously sustained, replenished
• 1:03:15
  Speaker 1: by the energy flowing out of the central black hole.
• 1:03:18
  Speaker 1: and threaded through the jet as new material is launched.
• 1:03:22
  Speaker 1: The connection between the field structure near the black hole
• 1:03:25
  Speaker 1: and the field structure at the outer lobes, 11 million
• 1:03:29
  Speaker 1: light years away on either side, is something that jet
• 1:03:33
  Speaker 1: physics at this scale has never had to account for before.
• 1:03:37
  Speaker 1: At smaller scales, models handle this reasonably well. At 7 megaparsecs,
• 1:03:43
  Speaker 1: the models are being pushed into territory they were not
• 1:03:46
  Speaker 1: designed for. there is another wrinkle. As the plasma moves
• 1:03:50
  Speaker 1: outward from the black hole and the electrons radiate away
• 1:03:53
  Speaker 1: their energy through synchrotron emission, those electrons lose energy. Old electrons,
• 1:04:00
  Speaker 1: far from the source, have been spiralling for much longer
• 1:04:04
  Speaker 1: and have radiated away a larger fraction of what they
• 1:04:07
  Speaker 1: started with. This means the outer regions of a jet,
• 1:04:10
  Speaker 1: in theory, should be populated by lower energy electrons producing
• 1:04:15
  Speaker 1: lower frequency radio emission. Detecting these faint outer regions requires
• 1:04:21
  Speaker 1: sensitivity at the lowest radio frequencies available, which is precisely
• 1:04:26
  Speaker 1: what LOFAR provides, and why LOFAR found Porphyrion when other
• 1:04:30
  Speaker 1: telescopes had not. The electrons in those outer lobes had
• 1:04:34
  Speaker 1: been spiralling and radiating for an enormous amount of time.
• 1:04:39
  Speaker 1: The signal they produce is faint. stretched to the lowest frequencies,
• 1:04:44
  Speaker 1: but it is still there. The magnetic field was still
• 1:04:47
  Speaker 1: there to keep them spiraling. Whatever kept those magnetic fields
• 1:04:51
  Speaker 1: locked in alignment across 23 million light years for billions
• 1:04:56
  Speaker 1: of years is not a question anyone has fully answered.
• 1:05:01
  Speaker 1: Two years before Perferion, the same team had already broken
• 1:05:05
  Speaker 1: the record once. In early 2022, Martyn Oe and his
• 1:05:10
  Speaker 1: colleagues at Leiden Observatory published a paper announcing the discovery
• 1:05:14
  Speaker 1: of a radio galaxy so large it required a name
• 1:05:18
  Speaker 1: from mythology to feel appropriate. They called it Alcyoneus. In
• 1:05:23
  Speaker 1: Greek tradition, Alcyoneus was one of the giants, a son
• 1:05:27
  Speaker 1: of Gaia, one of the most formidable opponents the Olympian
• 1:05:31
  Speaker 1: gods faced during their war against the giant-born. The astronomers
• 1:05:35
  Speaker 1: chose the name deliberately. What they had found was the
• 1:05:38
  Speaker 1: largest known structure of galactic origin ever measured. Its jets
• 1:05:43
  Speaker 1: stretched across roughly 16 million light years end to end.
• 1:05:48
  Speaker 1: That is about 100 Milky Ways laid in a line.
• 1:05:52
  Speaker 1: The previous record holder had not come close to that.
• 1:05:55
  Speaker 1: Alcyoneus did not nudge the record forward. It shattered it.
• 1:06:00
  Speaker 1: To understand what that meant, you have to know what
• 1:06:03
  Speaker 1: the field looked like before Alcyoneus arrived. Giant radio galaxies
• 1:06:08
  Speaker 1: have been catalogued for decades. Astronomers had moaned for a
• 1:06:12
  Speaker 1: long time that some black hole jets travel impressively far.
• 1:06:17
  Speaker 1: But impressively far, in the pre-LOFAR era, meant something far
• 1:06:22
  Speaker 1: more modest than 16 million light years. The largest confirmed
• 1:06:26
  Speaker 1: systems before 2022 spanned a few million light years at most.
• 1:06:32
  Speaker 1: Some of the most famous jet systems in the sky,
• 1:06:35
  Speaker 1: like Centaurus A, the nearest example visible from Earth, stretch
• 1:06:40
  Speaker 1: across roughly 10 Milky Ways. That was considered enormous. Centaurus
• 1:06:46
  Speaker 1: A sits close enough that its jets have been studied
• 1:06:49
  Speaker 1: in detail for generations. It appears in textbooks. It appears
• 1:06:54
  Speaker 1: in documentary footage. It is the kind of object that
• 1:06:57
  Speaker 1: feels definitive, like the upper boundary of what is possible.
• 1:07:02
  Speaker 1: Then Alcyoneus came in at 10 times that scale. and
• 1:07:06
  Speaker 1: the upper boundary ceased to exist. The host galaxy of
• 1:07:10
  Speaker 1: Alcyoneus is located about 3 billion light years from Earth.
• 1:07:14
  Speaker 1: That is far, but not as far as Porphyrian. Its jets,
• 1:07:18
  Speaker 1: like Porphyrian's, were detected in radio wavelengths at low frequencies.
• 1:07:23
  Speaker 1: Like Porphyrian, its structure had been sitting unrecognized in the sky,
• 1:07:28
  Speaker 1: too spread out and too faint at conventional wavelengths for
• 1:07:31
  Speaker 1: earlier surveys to catch its full extent. LOFAR changed that.
• 1:07:36
  Speaker 1: The low frequency sensitivity of the array revealed the full
• 1:07:39
  Speaker 1: reach of Alcyoneus' lobes in a way that no previous
• 1:07:43
  Speaker 1: instrument could. What had been invisible became visible almost overnight.
• 1:07:48
  Speaker 1: The paper describing Alcyoneus drew immediate attention. Here was a
• 1:07:53
  Speaker 1: structure produced by a single galaxy that reached across a
• 1:07:57
  Speaker 1: distance larger than most galaxy groups. Here was an object
• 1:08:02
  Speaker 1: that raised the same uncomfortable questions Porphyrian would raise two
• 1:08:06
  Speaker 1: years later. How does a jet hold together across that
• 1:08:10
  Speaker 1: kind of distance? What does it mean for the surrounding
• 1:08:13
  Speaker 1: environment when that much energy travels that far? The field
• 1:08:17
  Speaker 1: had new territory to explore, and Alcyoneus opened it. Then
• 1:08:22
  Speaker 1: something happened that almost never happens in the same research
• 1:08:25
  Speaker 1: group twice in two years. The record broke again. When
• 1:08:30
  Speaker 1: Porphyrian was announced in September 2024, it was not a
• 1:08:34
  Speaker 1: different team working independently and happening to find something larger.
• 1:08:39
  Speaker 1: It was the same group, Martino E, still at the
• 1:08:43
  Speaker 1: center of the work, this time based at Caltech. The
• 1:08:46
  Speaker 1: same LOFAR survey data pushed further, filtered differently, scrutinized more carefully.
• 1:08:53
  Speaker 1: Out of that same low-frequency sky, a second giant emerged.
• 1:08:59
  Speaker 1: This one stretched 23 million light-years from lobe to lobe,
• 1:09:04
  Speaker 1: 7 million light-years longer than Alcyoneus, roughly 140 Milky Ways
• 1:09:09
  Speaker 1: instead of 100. Another Greek giant, another structure that had
• 1:09:14
  Speaker 1: been sitting in the radio sky, undetected, Until the right
• 1:09:18
  Speaker 1: set of tools and the right set of eyes found it,
• 1:09:21
  Speaker 1: the gap between these two discoveries is worth sitting with.
• 1:09:25
  Speaker 1: Two years, the same survey, the same team. Two record-breaking
• 1:09:31
  Speaker 1: structures found one after the other. In most fields, breaking
• 1:09:36
  Speaker 1: a decades-old record once is a career-defining event. Breaking it again, immediately,
• 1:09:42
  Speaker 1: with an even larger object is something different. It suggests
• 1:09:47
  Speaker 1: the record itself was not a true ceiling. It suggests
• 1:09:51
  Speaker 1: the ceiling had not yet been found. Part of what
• 1:09:54
  Speaker 1: makes this pattern significant is what it says about the
• 1:09:57
  Speaker 1: survey rather than the objects themselves. LOFAR's 2-metre sky survey,
• 1:10:02
  Speaker 1: the LoTSS project, is not a targeted search. It is
• 1:10:06
  Speaker 1: a wide-field mapping effort, accumulating data across enormous areas of
• 1:10:11
  Speaker 1: the sky in the frequency range where extended radio lobes
• 1:10:15
  Speaker 1: glow most clearly. As more of the sky gets covered
• 1:10:18
  Speaker 1: at higher sensitivity, the population of detected structures grows. Alcyoneus
• 1:10:25
  Speaker 1: was found in one part of that survey. Porphyrian was
• 1:10:28
  Speaker 1: found in another. Neither was the result of a pointed
• 1:10:32
  Speaker 1: search for giant objects. Both emerged from systematic data analysis
• 1:10:37
  Speaker 1: of a survey designed to catalog everything the sky was
• 1:10:41
  Speaker 1: doing at low radio frequencies. This matters because it means
• 1:10:45
  Speaker 1: the sample is incomplete by definition. The low TSS survey
• 1:10:49
  Speaker 1: was still mapping the sky when both discoveries were made.
• 1:10:53
  Speaker 1: Large areas remained uncovered. The sensitivity at the edges of
• 1:10:58
  Speaker 1: the survey is lower than at the center. Processing pipelines
• 1:11:01
  Speaker 1: improve over time. and structures that were missed in earlier
• 1:11:05
  Speaker 1: runs sometimes appear in later analyses. Alcyoneus and Porphyrian are
• 1:11:10
  Speaker 1: the largest objects the survey has produced so far. They
• 1:11:14
  Speaker 1: are almost certainly not the largest objects the survey will
• 1:11:18
  Speaker 1: ever produce. There is a name for this kind of
• 1:11:21
  Speaker 1: situation in observational astronomy. It is called a detection bias
• 1:11:25
  Speaker 1: correction problem. What you find depends on what you are
• 1:11:29
  Speaker 1: able to find. Before LOFAR, The instruments available to survey
• 1:11:33
  Speaker 1: the low-frequency radio sky simply did not have the combination
• 1:11:38
  Speaker 1: of sensitivity, resolution and sky coverage needed to detect structures
• 1:11:43
  Speaker 1: at the scale of Alcyoneus or Porphyrium. They were not hiding,
• 1:11:47
  Speaker 1: they were emitting radio waves the entire time. The technology
• 1:11:51
  Speaker 1: to hear those waves across the full extent of the
• 1:11:54
  Speaker 1: jets did not exist in sufficient form until LOFAR's survey
• 1:11:58
  Speaker 1: data began accumulating. Alcyoneus and Porphyrian were not rare events
• 1:12:03
  Speaker 1: that happened to be discovered. They were always out there, broadcasting.
• 1:12:08
  Speaker 1: Astronomers just could not pick up the signal. What that
• 1:12:11
  Speaker 1: implies for the broader population is something researchers are now
• 1:12:15
  Speaker 1: actively working through. If two of the largest structures ever
• 1:12:19
  Speaker 1: found came out of the same survey in the same
• 1:12:22
  Speaker 1: two-year window, The survey is clearly sampling a population of
• 1:12:26
  Speaker 1: giant radio galaxies that previous catalogues systematically undercounted. How many
• 1:12:31
  Speaker 1: more Alcyonea-scale systems are sitting in the current data, unrecognised?
• 1:12:36
  Speaker 1: How many more at Porphyrian scale? How many at even
• 1:12:39
  Speaker 1: larger scales, in parts of the sky not yet covered
• 1:12:42
  Speaker 1: at full sensitivity? Nobody has a firm answer. The estimates
• 1:12:47
  Speaker 1: suggest the population of known giant radio galaxies will grow
• 1:12:50
  Speaker 1: substantially as the survey continues. Whether it will produce another
• 1:12:55
  Speaker 1: record holder, and how large that record holder will be,
• 1:12:59
  Speaker 1: is genuinely open. What the sequence of Alcyoneus and Porphyrian
• 1:13:04
  Speaker 1: demonstrates is that the largest known structures in the universe
• 1:13:08
  Speaker 1: are not stable discoveries. They are waypoints. Each one stands
• 1:13:14
  Speaker 1: as the largest until the survey reveals something larger. Alcyoneus
• 1:13:18
  Speaker 1: held that position for two years. Porphyrian took it. The
• 1:13:23
  Speaker 1: survey kept going after Porphyrian was announced. The fact that
• 1:13:27
  Speaker 1: both discoveries came from the same survey within two years
• 1:13:30
  Speaker 1: of each other was less a coincidence than a signal
• 1:13:34
  Speaker 1: that the survey was finding things nobody had been able
• 1:13:37
  Speaker 1: to look for before. Galaxies are not scattered randomly through
• 1:13:41
  Speaker 1: the universe. If you could step back far enough, far
• 1:13:45
  Speaker 1: enough that entire galaxy clusters looked like dust specks, You
• 1:13:50
  Speaker 1: would see something that nobody expected when astronomers first started
• 1:13:54
  Speaker 1: mapping the large-scale structure of the cosmos. The universe has
• 1:13:58
  Speaker 1: a shape. It is organized into a vast web. Enormous
• 1:14:03
  Speaker 1: filaments of gas and dark matter stretch across hundreds of
• 1:14:07
  Speaker 1: millions of light years, connecting galaxy clusters at their nodes
• 1:14:11
  Speaker 1: like threads connecting beads. Between those filaments sit voids. Not empty, exactly,
• 1:14:18
  Speaker 1: but close. Regions of space so underpopulated compared to the
• 1:14:23
  Speaker 1: filaments that matter there is spread almost unimaginably thin. This structure,
• 1:14:29
  Speaker 1: the filaments and the voids and the clusters at the intersections,
• 1:14:33
  Speaker 1: is what cosmologists call the cosmic web. It is the
• 1:14:37
  Speaker 1: skeleton of everything. The filaments are not a minor feature.
• 1:14:42
  Speaker 1: They are among the largest structures in the known universe.
• 1:14:46
  Speaker 1: A single filament can stretch for hundreds of millions of
• 1:14:49
  Speaker 1: light years. They are the highways along which gas travels,
• 1:14:53
  Speaker 1: funneling material down toward the dense galaxy clusters sitting at
• 1:14:57
  Speaker 1: their junctions. When astronomers talk about galaxies being fed by
• 1:15:01
  Speaker 1: cosmic filaments, this is what they mean. Matter flows along
• 1:15:06
  Speaker 1: those threads, falling inward under gravity, eventually reaching a galaxy
• 1:15:10
  Speaker 1: cluster and the galaxies inside it. The filament's shaped where
• 1:15:15
  Speaker 1: galaxies formed, which galaxies grew large, and which ones stalled.
• 1:15:20
  Speaker 1: They are not passive architecture. They are the plumbing of
• 1:15:23
  Speaker 1: the universe. Now hold that picture in your head. A
• 1:15:27
  Speaker 1: web of filaments, each hundreds of millions of light years long,
• 1:15:31
  Speaker 1: with vast voids stretching between them. The scale of a
• 1:15:35
  Speaker 1: single filament dwarfs anything a galaxy can produce. A galaxy,
• 1:15:40
  Speaker 1: even a large one, is a tiny node sitting somewhere
• 1:15:44
  Speaker 1: along one of those threads. The Milky Way, 100,000 light
• 1:15:49
  Speaker 1: years across, is essentially a rounding error on the scale
• 1:15:52
  Speaker 1: of a cosmic filament. No galaxy scale process was supposed
• 1:15:56
  Speaker 1: to reach filament scales. That was simply not how astronomers
• 1:16:00
  Speaker 1: thought about the influence of individual galaxies or their central
• 1:16:04
  Speaker 1: black holes. Local forces stayed local. The cosmic web was
• 1:16:08
  Speaker 1: a gravitational phenomenon, shaped by dark matter and the initial
• 1:16:13
  Speaker 1: conditions of the early universe. black holes were not part
• 1:16:17
  Speaker 1: of that picture, until Porphyrian. Porphyrian's jets extend 23 million
• 1:16:23
  Speaker 1: light years from end to end. The lobes, the two
• 1:16:27
  Speaker 1: enormous clouds of plasma sitting at the far reaches of
• 1:16:30
  Speaker 1: each jet, reach two-thirds of the way into the cosmic void,
• 1:16:34
  Speaker 1: the space between not just individual galaxies, but between superclusters
• 1:16:39
  Speaker 1: of galaxies. This is not a measurement that sits comfortably
• 1:16:43
  Speaker 1: in any previous category. Porphyrian is not reaching the edge
• 1:16:47
  Speaker 1: of its host galaxy cluster. It is not filling the
• 1:16:50
  Speaker 1: space between neighboring clusters. It is pushing into the emptiness
• 1:16:55
  Speaker 1: between superclusters, the deepest kind of void the universe contains.
• 1:17:00
  Speaker 1: Two-thirds of the way into that void. That is not
• 1:17:03
  Speaker 1: a local event. That is a cosmological one. Here is
• 1:17:07
  Speaker 1: the piece that makes the raw number even more striking.
• 1:17:11
  Speaker 1: When Porphyrian's jets were active, The universe was approximately 6.3
• 1:17:17
  Speaker 1: billion years old. The universe today is 13.8 billion years old.
• 1:17:23
  Speaker 1: This matters because the universe has been expanding this entire time.
• 1:17:28
  Speaker 1: The cosmic web has been stretching along with it. The
• 1:17:31
  Speaker 1: filaments that existed 7.5 billion years ago were compressed, closer together.
• 1:17:38
  Speaker 1: The voids between them were smaller, so when Porfirion's jets
• 1:17:42
  Speaker 1: were punching outward at that time, covering 23 million light
• 1:17:46
  Speaker 1: years in a universe that was roughly half its current size.
• 1:17:50
  Speaker 1: They were covering a larger fraction of the existing cosmic
• 1:17:54
  Speaker 1: web than the same distance would represent today. The web
• 1:17:58
  Speaker 1: was tighter. Porphyrian reached proportionally farther into it. A ruler
• 1:18:03
  Speaker 1: that crosses two-thirds of a room covers more of the
• 1:18:07
  Speaker 1: room than that same ruler in a larger room. The
• 1:18:10
  Speaker 1: universe has since expanded that room considerably. This is why
• 1:18:15
  Speaker 1: researchers describe Porphyreon as the first black hole jet to
• 1:18:19
  Speaker 1: operate at cosmic web scales. Not because 23 million light
• 1:18:24
  Speaker 1: years happens to match some arbitrary threshold, but because at
• 1:18:29
  Speaker 1: the time and place this jet existed, it genuinely reached
• 1:18:33
  Speaker 1: across a meaningful fraction of the universe's large scale structure.
• 1:18:37
  Speaker 1: It crossed from one kind of cosmic environment into another.
• 1:18:42
  Speaker 1: It started inside a galaxy cluster and ended in the
• 1:18:45
  Speaker 1: void between superclusters. Nothing produced by a single black hole
• 1:18:51
  Speaker 1: had been observed to do that before. What does it
• 1:18:54
  Speaker 1: actually mean to operate at cosmic web scales? Consider what
• 1:18:58
  Speaker 1: the filaments do. They transport matter. They channel gas from
• 1:19:03
  Speaker 1: the voids toward the dense regions where galaxies form and grow.
• 1:19:08
  Speaker 1: They are the supply lines. A jet that pushes energy
• 1:19:11
  Speaker 1: into those filaments, into the gas threading along those structures,
• 1:19:16
  Speaker 1: is not just affecting its neighborhood. It is interfering with
• 1:19:19
  Speaker 1: the plumbing. It is heating gas that was supposed to
• 1:19:23
  Speaker 1: cool and fall inward. It is pushing material that was
• 1:19:26
  Speaker 1: supposed to flow in one direction sideways. When astronomers talk
• 1:19:30
  Speaker 1: about Porphyrium reshaping its environment, they are not speaking loosely.
• 1:19:35
  Speaker 1: The jets were depositing energy directly into the medium that
• 1:19:39
  Speaker 1: feeds galaxy clusters and the galaxies inside them. Whatever gas
• 1:19:44
  Speaker 1: was flowing along the filament that Porphyrian's lobes reached into
• 1:19:48
  Speaker 1: was being heated and disturbed by a process that originated
• 1:19:51
  Speaker 1: 23 million light-years away in the core of a galaxy
• 1:19:56
  Speaker 1: it would never interact with gravitationally. The implications are not small.
• 1:20:01
  Speaker 1: If Porphyrian was not unique, and there is growing reason
• 1:20:04
  Speaker 1: to believe it was not, then jets at this scale
• 1:20:07
  Speaker 1: may have been operating throughout the early universe. The universe
• 1:20:11
  Speaker 1: at 6 billion years old was a busy, dense place.
• 1:20:15
  Speaker 1: Galaxy clusters were assembling. Filaments were channeling enormous quantities of gas.
• 1:20:21
  Speaker 1: Supermassive black holes across the universe were being fed at
• 1:20:25
  Speaker 1: high rates. If a meaningful fraction of them were producing
• 1:20:29
  Speaker 1: jets on the scale of Porphyrians, then the energy they
• 1:20:32
  Speaker 1: injected into the cosmic web would have been substantial. It
• 1:20:36
  Speaker 1: would have heated gas across large volumes. It would have
• 1:20:40
  Speaker 1: suppressed the formation of galaxies in some regions and perhaps
• 1:20:44
  Speaker 1: altered which filaments could efficiently channel material in others. The
• 1:20:48
  Speaker 1: distribution of galaxies we observe today, which parts of the
• 1:20:52
  Speaker 1: cosmic web are populated and which remain sparse, might carry
• 1:20:56
  Speaker 1: the mark of that activity. This is a genuinely new claim.
• 1:21:01
  Speaker 1: The standard model of cosmic structure formation is gravitational. Dark
• 1:21:05
  Speaker 1: matter collapses, pulls ordinary matter with it, filaments form, galaxies
• 1:21:11
  Speaker 1: condense at the nodes. Black holes were thought to influence
• 1:21:15
  Speaker 1: their immediate surroundings, their host galaxies, perhaps their clusters, but
• 1:21:21
  Speaker 1: not the cosmic web itself. Porphyrian broke that assumption by
• 1:21:25
  Speaker 1: simply being too large to ignore. Its lobes sat in
• 1:21:29
  Speaker 1: the void. The void is part of the cosmic web.
• 1:21:33
  Speaker 1: There is no version of this in which the energy
• 1:21:35
  Speaker 1: deposited there is a local event. What Porphyrian demonstrated at
• 1:21:40
  Speaker 1: the most basic level is that the boundary between galaxy-scale
• 1:21:44
  Speaker 1: physics and cosmic web-scale physics is not as firm as
• 1:21:48
  Speaker 1: the textbooks assumed. A single black hole, given the right
• 1:21:52
  Speaker 1: environment and enough time, can reach past its galaxy, past
• 1:21:57
  Speaker 1: its cluster, past neighboring clusters, and deposit energy in the
• 1:22:01
  Speaker 1: spaces between superclusters. That is not a local force. That
• 1:22:06
  Speaker 1: is something operating at the scale of the universe's own architecture.
• 1:22:11
  Speaker 1: Porphyrian was not just enormous by galactic standards. It was
• 1:22:16
  Speaker 1: enormous by the standards of the universe itself. The numbers
• 1:22:20
  Speaker 1: describing Porphyrian's energy output stop making intuitive sense very quickly.
• 1:22:26
  Speaker 1: Start with something familiar. Our sun the star that warms
• 1:22:31
  Speaker 1: every living thing on this planet, produces energy through nuclear
• 1:22:35
  Speaker 1: fusion at its core. Hydrogen atoms are fused into helium
• 1:22:39
  Speaker 1: under enormous pressure and heat, and the mass difference between
• 1:22:43
  Speaker 1: what goes in and what comes out converts into energy.
• 1:22:47
  Speaker 1: Every second, the Sun releases the equivalent of roughly 10
• 1:22:51
  Speaker 1: billion nuclear weapons going off simultaneously. That is the baseline.
• 1:22:57
  Speaker 1: That is the unit of comparison. The Sun has been
• 1:23:00
  Speaker 1: doing this for nearly 5 billion years without interruption, and
• 1:23:05
  Speaker 1: to any human measure, that makes it almost incomprehensibly powerful.
• 1:23:10
  Speaker 1: Porphyrian's jets outshine it by a factor of trillions. Not millions.
• 1:23:15
  Speaker 1: Not billions. Trillions. The combined power output of both jets
• 1:23:20
  Speaker 1: flowing from the black hole at the centre of that
• 1:23:23
  Speaker 1: host galaxy is estimated at the equivalent of several trillion
• 1:23:27
  Speaker 1: suns burning all at once. Not stars that size, not
• 1:23:31
  Speaker 1: stars of roughly solar luminosity. Suns, specifically, all running simultaneously.
• 1:23:38
  Speaker 1: If you lined up a trillion copies of our sun
• 1:23:41
  Speaker 1: and added them together, you would approach the energy budget
• 1:23:44
  Speaker 1: of what one black hole was pumping into space through
• 1:23:47
  Speaker 1: those two jets. The numbers do not translate into anything
• 1:23:51
  Speaker 1: a human being can hold in their head directly. What
• 1:23:55
  Speaker 1: you can do is work through the comparisons until the
• 1:23:58
  Speaker 1: strangeness starts to land. Here is one way to think
• 1:24:02
  Speaker 1: about it. The Milky Way contains somewhere between 200 and
• 1:24:06
  Speaker 1: 400 billion stars. Most of those stars are smaller and
• 1:24:10
  Speaker 1: dimmer than our sun. Some are larger and brighter. When
• 1:24:14
  Speaker 1: you add the full stellar population together, the entire galaxy
• 1:24:18
  Speaker 1: combined produces an enormous amount of light and energy. The
• 1:24:22
  Speaker 1: Milky Way is bright. You can see it from a
• 1:24:25
  Speaker 1: dark field on any clear night, a pale band stretching
• 1:24:29
  Speaker 1: across the sky. The combined glow of hundreds of billions
• 1:24:33
  Speaker 1: of stars accumulated over 100,000 light years of space. That
• 1:24:38
  Speaker 1: is everything in our galaxy contributing at once. Porphyrian's jets,
• 1:24:43
  Speaker 1: driven by a single black hole, outpaced that entire stellar
• 1:24:47
  Speaker 1: population by a significant margin. One object. Two jets. more
• 1:24:52
  Speaker 1: energy than every star in our galaxy combined, and doing
• 1:24:56
  Speaker 1: it from 7.5 billion light years away, in a host
• 1:25:00
  Speaker 1: galaxy that was not even especially massive by the standards
• 1:25:03
  Speaker 1: of the early universe. Now, the important question is where
• 1:25:07
  Speaker 1: that energy comes from, because it is not fusion. Black
• 1:25:12
  Speaker 1: holes do not fuse hydrogen. They do not burn fuel
• 1:25:15
  Speaker 1: in any conventional sense. The energy driving Porphyrion's jets comes
• 1:25:20
  Speaker 1: from something more fundamental, When matter falls toward a supermassive
• 1:25:24
  Speaker 1: black hole, it does not drop straight in. It forms
• 1:25:28
  Speaker 1: a rotating disk around the black hole, what astronomers call
• 1:25:31
  Speaker 1: an accretion disk. The material in this disk spirals inward,
• 1:25:36
  Speaker 1: and as it does, it releases gravitational potential energy. The
• 1:25:40
  Speaker 1: closer matter gets to the black hole before crossing the
• 1:25:43
  Speaker 1: point of no return, the more energy it sheds. The
• 1:25:48
  Speaker 1: black hole's gravity is converting the position of mass into
• 1:25:51
  Speaker 1: raw energy, and it does this with a ferocity that
• 1:25:55
  Speaker 1: nuclear fusion simply cannot match. Nuclear fusion, the process powering
• 1:26:01
  Speaker 1: every star in the universe, converts less than 1% of
• 1:26:05
  Speaker 1: the mass of its fuel into energy. It is efficient
• 1:26:08
  Speaker 1: by the standards of chemical combustion or anything a human
• 1:26:12
  Speaker 1: engineer has ever built. but by the standards of fundamental physics,
• 1:26:16
  Speaker 1: it wastes almost everything. Matter going through an accretion disk
• 1:26:20
  Speaker 1: around a rapidly spinning black hole can, in theory, convert
• 1:26:25
  Speaker 1: up to 40% of its rest mass into energy before
• 1:26:28
  Speaker 1: crossing the event horizon. That is not a small difference.
• 1:26:33
  Speaker 1: It is the difference between burning a candle and setting
• 1:26:36
  Speaker 1: off a nuclear warhead, and then setting off that warhead
• 1:26:40
  Speaker 1: versus something 40 times more potent again. Accretion around a
• 1:26:45
  Speaker 1: black hole is the most efficient large-scale energy conversion process
• 1:26:50
  Speaker 1: we know of in nature. What happens with that energy
• 1:26:54
  Speaker 1: is where the jets enter the picture. Not all of
• 1:26:57
  Speaker 1: the energy from infalling matter gets radiated away as light
• 1:27:01
  Speaker 1: from the disk. A fraction of it, through mechanisms involving
• 1:27:05
  Speaker 1: the disk's magnetic fields and the rotation of the black
• 1:27:08
  Speaker 1: hole itself, gets redirected into two narrow beams pointing in
• 1:27:13
  Speaker 1: opposite directions away from the disk. These are the jets.
• 1:27:17
  Speaker 1: Plasma gets accelerated along those magnetic field lines and launched
• 1:27:22
  Speaker 1: outward at near the speed of light. The fraction of
• 1:27:25
  Speaker 1: the total energy budget that ends up in the jets,
• 1:27:28
  Speaker 1: rather than radiated from the disk, depends on the specific conditions.
• 1:27:34
  Speaker 1: But even a modest fraction of trillions of solar luminosities
• 1:27:38
  Speaker 1: still represents an output that can carve through intergalactic space
• 1:27:42
  Speaker 1: for tens of millions of light years. The jets themselves
• 1:27:46
  Speaker 1: emerge from the magnetic field structure that threads through the
• 1:27:50
  Speaker 1: rotating accretion disk, a coupling between black hole spin and
• 1:27:54
  Speaker 1: the field's geometry that remains not entirely understood in every detail.
• 1:27:59
  Speaker 1: Yet observations of jets across many different black holes of
• 1:28:03
  Speaker 1: different sizes suggest the mechanism is robust and universal. What
• 1:28:08
  Speaker 1: is clear is that the jets do not constitute a continuous,
• 1:28:12
  Speaker 1: steady beam in the way we might imagine a fire hose. Rather,
• 1:28:17
  Speaker 1: they are channels of accelerated plasma whose properties vary across
• 1:28:21
  Speaker 1: their extent, their intensity shaped by variations in the accretion
• 1:28:26
  Speaker 1: rate and the black hole's magnetic configuration. The plasma moving
• 1:28:30
  Speaker 1: through these channels is not particularly dense by ordinary standards.
• 1:28:34
  Speaker 1: Captured and compressed, it would hardly fill your hand. What
• 1:28:38
  Speaker 1: makes it significant is velocity and energy density, the sheer
• 1:28:42
  Speaker 1: kinetic force of matter moving at relativistic speeds across scales
• 1:28:47
  Speaker 1: that span galaxies. There is something else worth sitting with here.
• 1:28:51
  Speaker 1: The jet did not reach 23 million light years in
• 1:28:54
  Speaker 1: a week. The plasma shooting out of the host galaxy's
• 1:28:58
  Speaker 1: black hole has been travelling outward and building that structure
• 1:29:02
  Speaker 1: across what physicists estimate must have been hundreds of millions
• 1:29:06
  Speaker 1: of years, and possibly longer. Some estimates stretch toward a
• 1:29:11
  Speaker 1: couple of billion years for a structure this large to accumulate.
• 1:29:15
  Speaker 1: That means the black hole was not just producing this
• 1:29:18
  Speaker 1: output for a moment, it was sustaining it for a
• 1:29:21
  Speaker 1: span of time comparable to the age of complex life
• 1:29:24
  Speaker 1: on Earth, or longer. Every year For hundreds of millions
• 1:29:28
  Speaker 1: of years, more plasma was being accelerated outward, more energy
• 1:29:33
  Speaker 1: was being deposited, more of the jet was being extended
• 1:29:37
  Speaker 1: into the surrounding space. The total energy that porphyrion has
• 1:29:41
  Speaker 1: put into its environment over its lifetime is something that
• 1:29:45
  Speaker 1: defies any clean analogy. To keep a jet running at
• 1:29:49
  Speaker 1: that output for that duration, the black hole needs matter
• 1:29:53
  Speaker 1: continuously falling into the accretion disk. This is not a
• 1:29:57
  Speaker 1: one-time event. It is a sustained process. The supply chain
• 1:30:01
  Speaker 1: of material feeding that black hole must have been essentially
• 1:30:05
  Speaker 1: uninterrupted across timescales measured in hundreds of millions of years.
• 1:30:11
  Speaker 1: That implies something specific about the environment the host galaxy
• 1:30:15
  Speaker 1: was sitting in. Something we will come to. But what
• 1:30:18
  Speaker 1: it tells you about the energy first is this. The
• 1:30:22
  Speaker 1: black hole did not run out. Whatever was feeding it
• 1:30:25
  Speaker 1: kept feeding it, the jets kept going, the energy kept
• 1:30:29
  Speaker 1: flowing outward into the cosmic void, heating gas, sweeping through filaments,
• 1:30:35
  Speaker 1: depositing power into structures on a scale that touches the
• 1:30:39
  Speaker 1: cosmic web itself. A sustained output at this level, kept
• 1:30:44
  Speaker 1: running long enough to build something 23 million light years across,
• 1:30:49
  Speaker 1: requires a fuel source with no obvious limits, and that
• 1:30:53
  Speaker 1: is where the story gets strange. The jets of Porphyrian
• 1:30:56
  Speaker 1: did not travel 23 million light years without doing anything.
• 1:31:01
  Speaker 1: Every light year of that distance represents plasma slamming into gas,
• 1:31:06
  Speaker 1: magnetic fields threading through surrounding material, and energy pouring into
• 1:31:11
  Speaker 1: spaces that were never quiet to begin with. The jets
• 1:31:15
  Speaker 1: are not just moving through the universe, they are changing it.
• 1:31:19
  Speaker 1: To understand what that means, you need to understand something
• 1:31:22
  Speaker 1: about how galaxies and gas interact. Between galaxies, and threading
• 1:31:27
  Speaker 1: through the filaments of the cosmic web, there is gas.
• 1:31:31
  Speaker 1: Not dense gas, not anything you could breathe or even
• 1:31:35
  Speaker 1: measure easily in a laboratory, but gas nonetheless. Thin, diffused,
• 1:31:41
  Speaker 1: stretched across enormous volumes, this gas is the raw material
• 1:31:45
  Speaker 1: for star formation. For a galaxy to keep building new stars,
• 1:31:50
  Speaker 1: it needs that gas to cool down, fall inward, and compress.
• 1:31:55
  Speaker 1: Cooling is the key step. Hot gas does not collapse.
• 1:31:59
  Speaker 1: It pushes back against gravity. It stays puffed up and
• 1:32:02
  Speaker 1: does nothing useful. Cold gas falls. Cold gas forms stars.
• 1:32:08
  Speaker 1: Now consider what a jet does to that gas. When
• 1:32:11
  Speaker 1: plasma shoots outward from a supermassive black hole at near
• 1:32:15
  Speaker 1: light speed, it carries energy. A tremendous amount of energy.
• 1:32:19
  Speaker 1: When that jet punches into surrounding gas clouds, it heats them.
• 1:32:24
  Speaker 1: It drives pressure waves outward through the medium, like a
• 1:32:28
  Speaker 1: shock wave expanding from a detonation. The gas temperature rises.
• 1:32:32
  Speaker 1: The cooling that was supposed to happen does not happen.
• 1:32:36
  Speaker 1: The gas that was supposed to fall inward and form
• 1:32:38
  Speaker 1: stars just sits there, hot and agitated, suspended against its
• 1:32:43
  Speaker 1: own gravity. This process has a name. Astronomers call it
• 1:32:48
  Speaker 1: jet feedback, or more specifically, radio mode feedback. It is
• 1:32:52
  Speaker 1: not a minor or theoretical effect. It is one of
• 1:32:55
  Speaker 1: the central mechanisms in modern galaxy evolution models. Without it,
• 1:33:00
  Speaker 1: simulations of the universe produce too many massive galaxies that
• 1:33:04
  Speaker 1: are too blue, too young, too full of stars. With it,
• 1:33:08
  Speaker 1: the most massive galaxies shut down. They turn red. They
• 1:33:12
  Speaker 1: go quiet. The feedback is real, and it leaves a
• 1:33:15
  Speaker 1: signature in the galaxies we observe. The massive elliptical galaxies
• 1:33:20
  Speaker 1: sitting at the centres of huge galaxy clusters are among
• 1:33:24
  Speaker 1: the most striking examples. These are some of the largest
• 1:33:28
  Speaker 1: galaxies in the known universe, containing hundreds of billions to
• 1:33:33
  Speaker 1: trillions of stars. You might expect objects that enormous to
• 1:33:37
  Speaker 1: be actively forming new stars constantly, fed by the enormous
• 1:33:41
  Speaker 1: gas reservoirs surrounding them. They are not. Most of them
• 1:33:45
  Speaker 1: are dead. Their star formation stopped long ago. The gas
• 1:33:49
  Speaker 1: that should have cooled and collapsed was heated repeatedly by
• 1:33:53
  Speaker 1: the jets of their central supermassive black holes. The black
• 1:33:57
  Speaker 1: hole kept the gas warm. The galaxy stopped growing. This
• 1:34:02
  Speaker 1: is not speculation. Astronomers have mapped the hot gas in
• 1:34:06
  Speaker 1: clusters using X-ray telescopes and found cavities, bubbles and ripples
• 1:34:11
  Speaker 1: in it that trace directly to the jets of the
• 1:34:14
  Speaker 1: central galaxy. The jets carved those holes. The jets drove
• 1:34:19
  Speaker 1: those waves. The physics is well established at the cluster scale.
• 1:34:24
  Speaker 1: The scale of that impact, however, operates in both directions.
• 1:34:28
  Speaker 1: Heating the gas slows star formation in the central galaxy,
• 1:34:32
  Speaker 1: but it also removes material that might otherwise flow outward
• 1:34:35
  Speaker 1: toward other structures. The feedback does not merely suppress, it
• 1:34:40
  Speaker 1: redirects and redistributes material. It alters the balance between gravitational
• 1:34:46
  Speaker 1: flows and thermal pressure within these systems. Porphyrian changes the
• 1:34:51
  Speaker 1: scale of the question entirely. A jet that reaches into
• 1:34:55
  Speaker 1: the filaments of the cosmic web is not just affecting
• 1:34:58
  Speaker 1: its host galaxy or its galaxy cluster. It is reaching
• 1:35:02
  Speaker 1: into the spaces between clusters, heating gas that feeds not
• 1:35:07
  Speaker 1: one galaxy, but potentially dozens of galaxies downstream. The filaments
• 1:35:12
  Speaker 1: of the cosmic web are not passive structures. They are channels.
• 1:35:17
  Speaker 1: Gas flows along them toward concentrations of mass. If a
• 1:35:21
  Speaker 1: jet the size of Porphyrion heats gas inside those filaments,
• 1:35:26
  Speaker 1: it is not suppressing star formation in one place. It
• 1:35:29
  Speaker 1: is interrupting the supply line for a whole network of
• 1:35:33
  Speaker 1: galaxies that depend on that gas to grow. Think of
• 1:35:36
  Speaker 1: a river feeding a dozen towns along its banks. Block
• 1:35:40
  Speaker 1: the river upstream. or heat it so that it evaporates
• 1:35:44
  Speaker 1: before reaching those towns, and every settlement downstream feels the shortage.
• 1:35:49
  Speaker 1: Porphyrian's jets extended two-thirds of the way into the cosmic void,
• 1:35:54
  Speaker 1: reaching beyond their own cluster and pressing into the filamentary
• 1:35:58
  Speaker 1: structures connecting the larger universe. The energy they deposited did
• 1:36:03
  Speaker 1: not stay local. A heating event in a filament does
• 1:36:07
  Speaker 1: not simply reduce downstream flow. It triggers cascade effects where
• 1:36:12
  Speaker 1: heated gas creates pressure gradients pushing material away from cooling zones.
• 1:36:18
  Speaker 1: The filament becomes not just a channel but a barrier
• 1:36:22
  Speaker 1: to essential processes. These effects compound substantially across cosmic scales.
• 1:36:28
  Speaker 1: How much energy was actually deposited is difficult to calculate precisely.
• 1:36:34
  Speaker 1: The jets have a total power output equivalent to trillions
• 1:36:37
  Speaker 1: of suns. Even if only a fraction of that energy
• 1:36:41
  Speaker 1: couples to the surrounding gas efficiently, the numbers are staggering.
• 1:36:46
  Speaker 1: Enough energy to heat an enormous column of intergalactic medium.
• 1:36:51
  Speaker 1: Enough to push gas out of filaments and into the
• 1:36:54
  Speaker 1: voids where it cannot be retrieved easily. Enough to alter
• 1:36:58
  Speaker 1: the growth trajectories of galaxies that never had any direct
• 1:37:01
  Speaker 1: contact with the jet itself. This is what astronomers mean
• 1:37:05
  Speaker 1: when they say, Porfirion may have influenced the evolution of
• 1:37:09
  Speaker 1: the universe more broadly than anyone had assumed. Not a
• 1:37:13
  Speaker 1: figure of speech, an accounting of where the energy went.
• 1:37:17
  Speaker 1: The jet put energy into the environment. That energy affected
• 1:37:21
  Speaker 1: gas temperatures. Those temperatures affected cooling rates. Those cooling rates
• 1:37:27
  Speaker 1: affected which galaxies got new material and which ones were
• 1:37:30
  Speaker 1: cut off. At Porfirion's scale, This chain of cause and
• 1:37:35
  Speaker 1: effect reaches across a region larger than galaxy clusters, larger
• 1:37:39
  Speaker 1: than the spaces between them, up to the scale of
• 1:37:42
  Speaker 1: the cosmic web itself. There is a subtler implication here
• 1:37:46
  Speaker 1: that researchers are still working through. Porphyrian existed when the
• 1:37:50
  Speaker 1: universe was roughly 6.3 billion years old. The universe at
• 1:37:55
  Speaker 1: that time was smaller, denser, more compressed. The filaments of
• 1:37:59
  Speaker 1: the cosmic web were closer together. A jet that reached
• 1:38:03
  Speaker 1: 23 million light-years across the sky covered a proportionally larger
• 1:38:07
  Speaker 1: fraction of the cosmic structure than the same jet would today.
• 1:38:11
  Speaker 1: The early universe was more tightly packed, and feedback operating
• 1:38:15
  Speaker 1: in that environment touched a larger share of the total
• 1:38:19
  Speaker 1: available gas. If jets like Porphyrian were not rare in
• 1:38:23
  Speaker 1: the early universe, if they were common, then the feedback
• 1:38:27
  Speaker 1: they produced was not a local story. It was a
• 1:38:30
  Speaker 1: story about the whole universe, playing out across its most
• 1:38:34
  Speaker 1: formative period of galaxy growth. That word common carries a
• 1:38:39
  Speaker 1: lot of weight. Before LOFAR began producing surveys of the
• 1:38:43
  Speaker 1: sensitivity it has achieved, Astronomers did not have a clear
• 1:38:47
  Speaker 1: census of how many jets at this scale existed. The
• 1:38:51
  Speaker 1: discovered population was small. The assumption was that such structures
• 1:38:56
  Speaker 1: were exceptional. Porphyrian and the discoveries immediately surrounding it are
• 1:39:01
  Speaker 1: beginning to challenge that assumption. If the survey keeps producing giants,
• 1:39:07
  Speaker 1: then what looked exceptional may turn out to be a category.
• 1:39:10
  Speaker 1: And a category of jets operating at cosmic web scales
• 1:39:14
  Speaker 1: during the epoch when most of the universe's stars were
• 1:39:17
  Speaker 1: being formed changes the calculation significantly. The galaxies we observe
• 1:39:23
  Speaker 1: today grew up in an environment shaped in part by
• 1:39:26
  Speaker 1: this feedback. Which ones received a steady supply of cold
• 1:39:30
  Speaker 1: and falling gas and which ones did not is partly
• 1:39:34
  Speaker 1: a gravitational story. But it is also apparently partly a
• 1:39:38
  Speaker 1: story about where the jets were and how large they got.
• 1:39:43
  Speaker 1: If this kind of feedback operated across cosmic web scales
• 1:39:46
  Speaker 1: in the early universe, then the distribution of galaxies we
• 1:39:50
  Speaker 1: see today may carry the fingerprints of black holes we
• 1:39:53
  Speaker 1: have not yet found. The most unsettling thing about Porphyrian
• 1:39:58
  Speaker 1: is not its size, but the duration required to build it.
• 1:40:02
  Speaker 1: When astronomers look at the jets and try to work backward,
• 1:40:05
  Speaker 1: the numbers become uncomfortable. Jets do not travel at the
• 1:40:09
  Speaker 1: speed of light. The plasma moves fast, close to it
• 1:40:13
  Speaker 1: in some regions, but the process of building a jet
• 1:40:17
  Speaker 1: structure across millions of light years is not instantaneous. It
• 1:40:22
  Speaker 1: is geological. Physicists working through the models estimate that reaching
• 1:40:27
  Speaker 1: a scale of 23 million light years would have taken
• 1:40:30
  Speaker 1: somewhere between several hundred million and a couple of billion
• 1:40:34
  Speaker 1: years of sustained output. That is not a burst. That
• 1:40:38
  Speaker 1: is not a flare. That is a black hole that
• 1:40:41
  Speaker 1: essentially never stopped eating for longer than complex life has
• 1:40:45
  Speaker 1: existed on Earth. Think about what that requires. Every day,
• 1:40:50
  Speaker 1: for what may have been a billion years or more,
• 1:40:53
  Speaker 1: material had to fall toward the center of that galaxy,
• 1:40:57
  Speaker 1: get caught in the accretion disk, and get redirected outward
• 1:41:01
  Speaker 1: into the jets. The engine never stalled. The fuel never
• 1:41:06
  Speaker 1: ran out. Something kept feeding it. This does not happen
• 1:41:10
  Speaker 1: by accident. When astronomers look at the most extreme jet
• 1:41:14
  Speaker 1: systems in the known universe, there is a pattern. The
• 1:41:17
  Speaker 1: largest jets tend to come from galaxies sitting in the
• 1:41:20
  Speaker 1: richest environments. Dense knots of gas, thick filaments of the
• 1:41:25
  Speaker 1: cosmic web funneling material inward, galaxy clusters wherein falling matter
• 1:41:30
  Speaker 1: is abundant and continuous. The host galaxy of Porphyrian, at
• 1:41:35
  Speaker 1: roughly 10 times the mass of the Milky Way, was
• 1:41:38
  Speaker 1: a substantial object. It was not the most massive galaxy
• 1:41:42
  Speaker 1: in the universe at the time it existed. There are
• 1:41:45
  Speaker 1: galaxies heavier by a significant margin. But mass alone does
• 1:41:50
  Speaker 1: not determine how well a black hole feeds. Location matters.
• 1:41:54
  Speaker 1: The supply lines matter. A black hole sitting at the
• 1:41:58
  Speaker 1: junction of several dense cosmic filaments has access to material
• 1:42:03
  Speaker 1: that a more isolated galaxy simply does not. The evidence
• 1:42:07
  Speaker 1: from Porphyrion's scale strongly suggests its host galaxy was exceptionally
• 1:42:12
  Speaker 1: well positioned. It was not just massive, it was connected.
• 1:42:16
  Speaker 1: The cosmic web at that epoch, 7.5 billion years ago,
• 1:42:21
  Speaker 1: was more compressed than it is today. The universe was younger, smaller,
• 1:42:27
  Speaker 1: and the filaments threading through it were closer together. Gas
• 1:42:30
  Speaker 1: densities in those filaments were higher. The highways feeding galaxies
• 1:42:35
  Speaker 1: were more active. A galaxy sitting inside or near a
• 1:42:39
  Speaker 1: dense node of that web would have had a nearly
• 1:42:41
  Speaker 1: continuous supply of raw material arriving from multiple directions. This
• 1:42:47
  Speaker 1: is the environment that can sustain a jet for a
• 1:42:50
  Speaker 1: billion years. Strip that galaxy of its location, move it
• 1:42:54
  Speaker 1: to a void, cut off the incoming gas, and the
• 1:42:58
  Speaker 1: jets would eventually starve and fade. Location is not a
• 1:43:02
  Speaker 1: minor variable here. It may be the central one. Here
• 1:43:06
  Speaker 1: is where the story gets stranger. The jet itself may
• 1:43:09
  Speaker 1: have been shaping the conditions that kept it running. As
• 1:43:12
  Speaker 1: Porphyrian's jets travelled outward, they were not passing through empty space.
• 1:43:18
  Speaker 1: They were moving through gas. Hot plasma punching into that
• 1:43:21
  Speaker 1: surrounding medium transfers energy into it. The gas heats up.
• 1:43:26
  Speaker 1: Heated gas does not cool easily. Gas that cannot cool
• 1:43:30
  Speaker 1: cannot collapse. Gas that cannot collapse cannot form stars. and
• 1:43:35
  Speaker 1: it cannot fall inward toward the galaxy's center as efficiently either.
• 1:43:40
  Speaker 1: This is the mechanism astronomers call jet feedback, and it
• 1:43:44
  Speaker 1: cuts in two directions. On one hand, the jets heat
• 1:43:48
  Speaker 1: the surrounding gas and suppress what would otherwise happen to it.
• 1:43:52
  Speaker 1: On the other hand, the same heating can regulate the
• 1:43:55
  Speaker 1: inflow rate, keeping the supply of infalling material steady rather
• 1:43:59
  Speaker 1: than letting it all dump in at once and overwhelm
• 1:44:02
  Speaker 1: the system. What this produces is something close to a
• 1:44:06
  Speaker 1: self-regulating engine. The black hole eats. The jets fire. The
• 1:44:11
  Speaker 1: jets heat the surrounding gas. The heated gas falls inward
• 1:44:15
  Speaker 1: more slowly and more steadily. This controlled in fall means
• 1:44:19
  Speaker 1: the black hole keeps receiving fuel at a manageable rate
• 1:44:23
  Speaker 1: rather than in violent, unpredictable bursts. The jets stay on.
• 1:44:28
  Speaker 1: The cycle continues. This is not a theory invented to
• 1:44:32
  Speaker 1: explain porphyrion. Versions of this self-modulating behaviour have been observed
• 1:44:37
  Speaker 1: in other radio galaxies and in galaxy clusters where black
• 1:44:41
  Speaker 1: hole feedback keeps the central gas from cooling catastrophically. But
• 1:44:46
  Speaker 1: porphyrion operates this mechanism at a scale that makes the
• 1:44:50
  Speaker 1: local examples look modest. The same feedback loop, running for
• 1:44:54
  Speaker 1: long enough, in a rich enough environment produced something that
• 1:44:58
  Speaker 1: extended across a significant fraction of the cosmic web. The
• 1:45:03
  Speaker 1: question of why some black holes produce jets at all,
• 1:45:06
  Speaker 1: while others of similar mass do not, is one of
• 1:45:09
  Speaker 1: the open problems in astrophysics. The spin of the black
• 1:45:13
  Speaker 1: hole matters. A rapidly spinning black hole can extract energy
• 1:45:17
  Speaker 1: from its own rotation and channel it into the jets
• 1:45:21
  Speaker 1: through a process involving the twisting of magnetic field lines
• 1:45:24
  Speaker 1: near the event horizon. Porphyrian's black hole, to have sustained
• 1:45:29
  Speaker 1: output at this level for this long, was almost certainly
• 1:45:32
  Speaker 1: spinning fast. Possibly near the maximum allowed by physics, a
• 1:45:37
  Speaker 1: slowly spinning black hole bleeds less energy into the jets.
• 1:45:41
  Speaker 1: A fast spinner can sustain them. But spin alone does
• 1:45:44
  Speaker 1: not explain Porphyrian. Spin sets the efficiency of the engine,
• 1:45:49
  Speaker 1: the fuel supply determines how long it runs. What the
• 1:45:53
  Speaker 1: full picture suggests is a convergence of conditions. A massive galaxy,
• 1:45:59
  Speaker 1: sitting in a dense region of the early cosmic web,
• 1:46:02
  Speaker 1: with a rapidly spinning supermassive black hole at its centre,
• 1:46:07
  Speaker 1: surrounded by abundant gas flowing in from multiple filaments, and
• 1:46:11
  Speaker 1: a feedback loop keeping the infall rate stable enough that
• 1:46:15
  Speaker 1: the engine never choked and never starved. Remove any one
• 1:46:19
  Speaker 1: of those conditions and you likely do not get porphyrion.
• 1:46:23
  Speaker 1: You get something smaller, something that ran out of fuel early,
• 1:46:27
  Speaker 1: something that dissipated before it reached its observed scale. The
• 1:46:31
  Speaker 1: fact that we found one of these structures does not
• 1:46:34
  Speaker 1: mean they are everywhere. It may mean that the precise
• 1:46:37
  Speaker 1: combination of conditions required to build them is rare. and
• 1:46:41
  Speaker 1: LOFAR was finally sensitive enough to find one when it
• 1:46:45
  Speaker 1: looked carefully enough across a large enough portion of the sky.
• 1:46:49
  Speaker 1: There is also the question of timing. The universe at 6.3
• 1:46:53
  Speaker 1: billion years old was going through a phase when supermassive
• 1:46:57
  Speaker 1: black holes were, on average, more active than they are today.
• 1:47:02
  Speaker 1: The era of peak quasar activity, the era when the
• 1:47:05
  Speaker 1: most powerful engines in the universe were running at full capacity,
• 1:47:10
  Speaker 1: Porphyrion was born in that window. It had access to
• 1:47:13
  Speaker 1: the fuel-rich conditions of an early, denser universe, and it
• 1:47:17
  Speaker 1: had the location and the spin to make use of them.
• 1:47:21
  Speaker 1: It is not an accident that one of the largest
• 1:47:23
  Speaker 1: structures ever produced by a single galaxy comes from this
• 1:47:28
  Speaker 1: particular period in cosmic history, rather than from the universe
• 1:47:32
  Speaker 1: as it exists today. A jet that feeds for that
• 1:47:36
  Speaker 1: long is not a random accident. It is the product
• 1:47:40
  Speaker 1: of a galaxy sitting in exactly the right place at
• 1:47:43
  Speaker 1: exactly the right time in cosmic history. For decades, the
• 1:47:48
  Speaker 1: accepted picture was that supermassive black holes were local forces.
• 1:47:53
  Speaker 1: They governed their host galaxies. They heated the gas in
• 1:47:57
  Speaker 1: their immediate clusters. They punched jets into the surrounding medium.
• 1:48:02
  Speaker 1: And the medium pushed back. And that was where the
• 1:48:05
  Speaker 1: story ended. The influence of a black hole, however enormous,
• 1:48:10
  Speaker 1: was thought to be fundamentally contained, a neighborhood phenomenon in
• 1:48:15
  Speaker 1: a universe of neighborhoods. Porphyrium changed that assumption in a
• 1:48:19
  Speaker 1: specific and measurable way. The jets of Porphyrium did not
• 1:48:24
  Speaker 1: stop at the edge of their host galaxy. They did
• 1:48:27
  Speaker 1: not stop at the edge of the galaxy cluster surrounding it.
• 1:48:31
  Speaker 1: They pushed two-thirds of the way into the cosmic void,
• 1:48:34
  Speaker 1: the near-empty space between superclusters. And they did it 7.5
• 1:48:39
  Speaker 1: billion years ago, when the universe was smaller and those
• 1:48:43
  Speaker 1: voids were more compressed. What this means is that the
• 1:48:46
  Speaker 1: energy from a single supermassive black hole reached structures that
• 1:48:50
  Speaker 1: were supposed to exist entirely outside its domain. Not its galaxy.
• 1:48:56
  Speaker 1: Not its cluster. The filaments themselves. The skeleton of the universe.
• 1:49:01
  Speaker 1: To understand why this is significant, you need to hold
• 1:49:05
  Speaker 1: two ideas at once. The first is that the cosmic web,
• 1:49:10
  Speaker 1: the vast network of gas filaments and dark matter threading
• 1:49:14
  Speaker 1: through the universe, was thought to be shaped almost entirely
• 1:49:18
  Speaker 1: by gravity. Dark matter collapsed first. Gas followed. Galaxies formed
• 1:49:24
  Speaker 1: along the filaments where density was highest. The voids emptied out.
• 1:49:29
  Speaker 1: This picture is gravitational from start to finish. Gravity built
• 1:49:33
  Speaker 1: the web, and the web determined where galaxies grew. black
• 1:49:37
  Speaker 1: holes were passengers in this story, not architects. The second
• 1:49:42
  Speaker 1: idea is that Porphyrian suggests this picture is incomplete. If
• 1:49:46
  Speaker 1: a single black hole could push jets across a meaningful
• 1:49:49
  Speaker 1: fraction of the filament scale, then black holes were not
• 1:49:52
  Speaker 1: just passengers. They were adding energy to the web itself,
• 1:49:57
  Speaker 1: heating gas in regions that gravity was trying to pull together,
• 1:50:01
  Speaker 1: pushing back against the very process that was building large-scale structure.
• 1:50:06
  Speaker 1: That is not a minor footnote. That is a revision
• 1:50:09
  Speaker 1: to the foundational model of how the universe assembled itself.
• 1:50:13
  Speaker 1: Here is the practical consequence. Gas in the cosmic filaments
• 1:50:17
  Speaker 1: is the raw material for future galaxies. When that gas cools,
• 1:50:21
  Speaker 1: it falls into potential wells and forms stars. When something
• 1:50:26
  Speaker 1: heats it, the cooling slows, the infall slows, and star
• 1:50:30
  Speaker 1: formation stalls. Galaxy clusters contain this process through what astronomers
• 1:50:35
  Speaker 1: call radio mode feedback. Jets from central black holes reheat
• 1:50:40
  Speaker 1: gas that would otherwise cool and collapse. But that feedback
• 1:50:44
  Speaker 1: was assumed to stay inside the cluster. Porphyrian's jets reach
• 1:50:48
  Speaker 1: the filaments feeding the cluster from outside. That is a
• 1:50:52
  Speaker 1: different scale of intervention entirely. Think about what that means
• 1:50:57
  Speaker 1: for any galaxy trying to form along a filament that
• 1:51:00
  Speaker 1: a Porphyrian-scale jet was threading through. The gas it needed
• 1:51:04
  Speaker 1: was being heated by energy from a black hole in
• 1:51:07
  Speaker 1: a different galaxy entirely, in a different part of the web.
• 1:51:12
  Speaker 1: The formation history of that galaxy was being written, at
• 1:51:15
  Speaker 1: least in part, by a source it had no direct
• 1:51:18
  Speaker 1: relationship with. A black hole 23 million light years away
• 1:51:23
  Speaker 1: was influencing its future. Nothing in the standard model of
• 1:51:27
  Speaker 1: galaxy formation had room for that. The researchers behind the
• 1:51:31
  Speaker 1: Porphyrian discovery were careful about how they stated this. They
• 1:51:36
  Speaker 1: did not claim that black holes built the cosmic web
• 1:51:38
  Speaker 1: from scratch. What they said was that supermassive black holes
• 1:51:43
  Speaker 1: do not only hold sway over the galaxy, but also
• 1:51:46
  Speaker 1: over the cosmic web that surrounds them. That is a narrow,
• 1:51:50
  Speaker 1: defensible claim. But the implications widen quickly when you ask
• 1:51:54
  Speaker 1: the obvious follow-up question. If one black hole did this,
• 1:51:58
  Speaker 1: how many others did two? The answer is not yet known.
• 1:52:03
  Speaker 1: What is known is that Porphyrian was observed at a
• 1:52:05
  Speaker 1: time when the universe was roughly 6.3 billion years old,
• 1:52:10
  Speaker 1: less than half its current age. The early universe was
• 1:52:13
  Speaker 1: more active. Supermassive black holes were feeding faster, generating more
• 1:52:18
  Speaker 1: powerful jets across a more compressed and denser cosmic web.
• 1:52:23
  Speaker 1: If jet systems at Porphyrian scale were common in that epoch,
• 1:52:27
  Speaker 1: then the energy they deposited into filaments and voids not
• 1:52:31
  Speaker 1: a local anomaly. It was a widespread influence operating across
• 1:52:36
  Speaker 1: the observable universe at exactly the time when the large-scale
• 1:52:41
  Speaker 1: structure of the cosmos was still being decided. The implications
• 1:52:45
  Speaker 1: of this timing are profound for understanding cosmic evolution. In
• 1:52:50
  Speaker 1: that earlier epoch, galaxies were still assembling from primordial material,
• 1:52:55
  Speaker 1: and the density of the cosmic filaments was significantly higher
• 1:52:58
  Speaker 1: than today. The jets from black holes like Porphyrian would
• 1:53:03
  Speaker 1: have encountered gas that was actively flowing along these filaments,
• 1:53:07
  Speaker 1: material still in the process of cooling and contracting under gravity.
• 1:53:11
  Speaker 1: By introducing heat at this critical moment, supermassive black holes
• 1:53:16
  Speaker 1: could have fundamentally altered the trajectory of structure formation. The
• 1:53:20
  Speaker 1: timing places this feedback mechanism precisely when the Universe was
• 1:53:24
  Speaker 1: transitioning from rapid growth to slower accretion rates. Early intervention
• 1:53:30
  Speaker 1: at this stage would have had cascading effects, rippling outward
• 1:53:34
  Speaker 1: through the web and affecting the entire network of cosmic filaments.
• 1:53:38
  Speaker 1: This is what makes the discovery difficult to absorb. It
• 1:53:41
  Speaker 1: is not just that one object was unexpectedly large. It
• 1:53:45
  Speaker 1: is that the existence of that object opens a question
• 1:53:48
  Speaker 1: about the entire architecture of the universe. The arrangement of
• 1:53:52
  Speaker 1: filaments and voids we see today, the reason galaxies cluster
• 1:53:56
  Speaker 1: here and not there, The reason certain regions of space
• 1:53:59
  Speaker 1: are rich with structure and others are nearly empty may
• 1:54:03
  Speaker 1: carry the signature of black hole activity from 7 or
• 1:54:06
  Speaker 1: 8 billion years ago. Activity that left no obvious visible trace.
• 1:54:12
  Speaker 1: Activity that only became detectable when a radio telescope sensitive
• 1:54:16
  Speaker 1: enough to pick up faint emission at low frequencies finally
• 1:54:20
  Speaker 1: scanned the right patch of sky. Astronomers working on large-scale
• 1:54:25
  Speaker 1: structure simulations now face a genuine question about whether their
• 1:54:28
  Speaker 1: models are missing a term. The standard cosmological framework– dark matter,
• 1:54:34
  Speaker 1: dark energy, gravity, and initial conditions from the Big Bang–
• 1:54:39
  Speaker 1: produces a cosmic web that matches observations reasonably well. But
• 1:54:43
  Speaker 1: reasonably well is not the same as exactly. There are
• 1:54:47
  Speaker 1: tensions in the model. There are regions where the observed
• 1:54:50
  Speaker 1: distribution of galaxies does not quite match the predictions. Nobody
• 1:54:55
  Speaker 1: is claiming that Porphyrion scale feedback explains all of these discrepancies.
• 1:55:00
  Speaker 1: But the possibility that widespread black hole jet activity in
• 1:55:04
  Speaker 1: the early universe deposited energy into the web at scales
• 1:55:08
  Speaker 1: the simulations never included is now a serious subject of
• 1:55:12
  Speaker 1: investigation rather than a fringe idea. What changed with Porphyrian
• 1:55:18
  Speaker 1: is not just the record. What changed is the scope
• 1:55:21
  Speaker 1: of the question. Before Porphyrian, the question was how black
• 1:55:25
  Speaker 1: holes regulate their host galaxies. That question still matters. It
• 1:55:30
  Speaker 1: is still being studied. But now there is a second
• 1:55:34
  Speaker 1: question sitting next to it, larger and harder to answer.
• 1:55:39
  Speaker 1: Whether a black hole can influence not just a galaxy,
• 1:55:42
  Speaker 1: not just a cluster, but the filaments connecting clusters to
• 1:55:46
  Speaker 1: each other, whether the energy from objects this small, measured
• 1:55:51
  Speaker 1: against the scale of the universe, could have left marks
• 1:55:54
  Speaker 1: on the larger structures that exist. The question now being
• 1:55:58
  Speaker 1: asked seriously for the first time is whether the large-scale
• 1:56:02
  Speaker 1: architecture of the universe, the web of filaments and voids
• 1:56:06
  Speaker 1: that everything we know lives inside, was shaped in part
• 1:56:10
  Speaker 1: by objects no bigger than a solar system sitting at
• 1:56:13
  Speaker 1: the centers of galaxies. Porphyreon did not hold the record
• 1:56:18
  Speaker 1: for long. Sometime in the same year that Martín Oe's
• 1:56:22
  Speaker 1: team published their findings in Nature, another radio galaxy quietly
• 1:56:27
  Speaker 1: entered the picture. Its designation is TXS 0033 plus 252.
• 1:56:30
  Speaker 1: It does not have a mythological nickname yet. It does
• 1:56:38
  Speaker 1: not carry the name of a rebellious giant or a
• 1:56:41
  Speaker 1: creature of ancient legend. It is a string of numbers
• 1:56:44
  Speaker 1: and letters in a catalogue that most people will never read.
• 1:56:48
  Speaker 1: But what it has is size. Researchers examining radio survey
• 1:56:53
  Speaker 1: data identified its jet structure as spanning approximately 8 megaparsecs,
• 1:56:58
  Speaker 1: which converts to roughly 26 million light years from end
• 1:57:02
  Speaker 1: to end. Porphyrium at 7 megaparsecs. had stood as the
• 1:57:07
  Speaker 1: largest known jet structure in the universe for a matter
• 1:57:10
  Speaker 1: of months before something larger turned up. The record had
• 1:57:14
  Speaker 1: already been broken once when Porphyrian surpassed Alcyoneus in 2024.
• 1:57:19
  Speaker 1: Now it was broken again, almost immediately. That is a
• 1:57:23
  Speaker 1: strange thing to sit with. Two records in a single year,
• 1:57:28
  Speaker 1: both involving structures that dwarf anything previously catalogued, both arriving
• 1:57:33
  Speaker 1: in such rapid succession that the first barely had time
• 1:57:37
  Speaker 1: to be absorbed before the second appeared. The obvious question
• 1:57:41
  Speaker 1: is whether this is coincidence. It is not. The pace
• 1:57:44
  Speaker 1: of these discoveries is not the product of luck or
• 1:57:47
  Speaker 1: a sudden burst of astronomical inspiration. It is the product
• 1:57:51
  Speaker 1: of instruments finally operating at the sensitivity and frequency range
• 1:57:55
  Speaker 1: required to see this class of object at all. Before
• 1:57:59
  Speaker 1: LOFAR class surveys became available, Giant radio galaxies existed in
• 1:58:04
  Speaker 1: the universe the same way they exist now. They were
• 1:58:07
  Speaker 1: out there. They were enormous. Nobody could find them, not
• 1:58:11
  Speaker 1: because nobody was looking, but because the tools available were
• 1:58:15
  Speaker 1: not built to detect structures this faint, and this extended
• 1:58:19
  Speaker 1: at the radio frequencies where jet lobes glow most clearly.
• 1:58:24
  Speaker 1: Porphyrian and TXS 0033 plus 252 are did not appear
• 1:58:31
  Speaker 1: because the universe suddenly started producing giants. They appeared because
• 1:58:35
  Speaker 1: the survey finally reached the depth required to pull them
• 1:58:39
  Speaker 1: out of the noise. Think about what that implies. If
• 1:58:43
  Speaker 1: two of the largest structures ever discovered showed up within
• 1:58:46
  Speaker 1: the same survey, within the same two-year window, the reasonable
• 1:58:51
  Speaker 1: conclusion is not that the universe produced two exceptional objects
• 1:58:55
  Speaker 1: close together in time. The reasonable conclusion is that there
• 1:59:00
  Speaker 1: are more. Many more. The catalogue of known giant radio
• 1:59:05
  Speaker 1: galaxies is almost certainly incomplete, not by a small margin,
• 1:59:09
  Speaker 1: but by a significant one. Every structure that has held
• 1:59:13
  Speaker 1: a record so far has been found at the frontier
• 1:59:16
  Speaker 1: of current sensitivity. That frontier is still moving. As it moves,
• 1:59:22
  Speaker 1: what sits just beyond it, is a population of objects
• 1:59:26
  Speaker 1: that existing instruments have not yet seen clearly enough to measure, classify,
• 1:59:31
  Speaker 1: or name. This is what astronomers mean when they say
• 1:59:34
  Speaker 1: that Porphyrian may represent a class rather than an exception.
• 1:59:39
  Speaker 1: The individual object matters less than what its existence signals
• 1:59:43
  Speaker 1: about the population it belongs to. If JET system's 20
• 1:59:47
  Speaker 1: million light years or more in extent were rare anomalies,
• 1:59:51
  Speaker 1: You would not expect two of them to appear in
• 1:59:54
  Speaker 1: the same survey within months of each other. What you
• 1:59:57
  Speaker 1: would expect instead is exactly what has happened. A trickle
• 2:00:01
  Speaker 1: at first, then a steadier flow. The survey sensitivity increases
• 2:00:07
  Speaker 1: and more of the sky is mapped at the right frequencies.
• 2:00:11
  Speaker 1: The question shifts from whether these giants exist to how
• 2:00:14
  Speaker 1: many of them exist and what role they played in
• 2:00:17
  Speaker 1: the early universe. The search for more of them is
• 2:00:21
  Speaker 1: already underway. LOFAR continues operating, and its 2-metre sky survey
• 2:00:27
  Speaker 1: is far from finished, mapping the portions of sky it
• 2:00:30
  Speaker 1: has not yet covered. The resolution and depth of the
• 2:00:33
  Speaker 1: survey are being pushed further with each data release. Researchers
• 2:00:38
  Speaker 1: are also combining LOFAR data with observations from the giant
• 2:00:42
  Speaker 1: Metrowave radio telescope in India. which operates at overlapping frequencies
• 2:00:47
  Speaker 1: and provides a different angular resolution, filling in structural details
• 2:00:52
  Speaker 1: that LOFAR alone cannot fully resolve. The Square Kilometre Array,
• 2:00:57
  Speaker 1: currently under construction in South Africa and Australia, will eventually
• 2:01:01
  Speaker 1: come online with sensitivity and sky coverage that dwarfs anything
• 2:01:06
  Speaker 1: currently operational. When it does, the list of known giants
• 2:01:10
  Speaker 1: will almost certainly grow faster than individual researchers can keep
• 2:01:14
  Speaker 1: up with, What makes TXS 0033 plus 252 particularly interesting
• 2:01:21
  Speaker 1: beyond its raw size is how little is known about
• 2:01:25
  Speaker 1: it compared to Porphyrian. Porphyrian was confirmed using Keck Observatory
• 2:01:30
  Speaker 1: spectroscopy to pin down the redshift of its host galaxy
• 2:01:35
  Speaker 1: and lock in its distance of 7.5 billion light years.
• 2:01:40
  Speaker 1: The host galaxy was identified. The physical dimensions were calculated carefully.
• 2:01:46
  Speaker 1: With TXS0033 plus 252, the measurement of 8 megaparsecs is
• 2:01:53
  Speaker 1: an estimated figure, and the confirmation work that OEI's team
• 2:01:57
  Speaker 1: did so meticulously for Porphyrium has not yet reached the
• 2:02:01
  Speaker 1: same stage of completeness. That is not a criticism. It
• 2:02:05
  Speaker 1: is simply the state of a fast-moving field, where the
• 2:02:09
  Speaker 1: rate of discovery has outpaced the rate of follow-up observation.
• 2:02:13
  Speaker 1: Each new object found requires telescope time, careful distance confirmation,
• 2:02:19
  Speaker 1: host galaxy identification and detailed structural mapping. There are only
• 2:02:24
  Speaker 1: so many large observatories and the queue is long. This
• 2:02:29
  Speaker 1: lag between discovery and full characterisation is itself a feature
• 2:02:34
  Speaker 1: of the current moment in radio astronomy. Survey instruments are
• 2:02:38
  Speaker 1: cataloguing faster than follow-up instruments can confirm. This means the
• 2:02:43
  Speaker 1: true census of giant radio galaxies is both growing and
• 2:02:47
  Speaker 1: unresolved simultaneously. Researchers know the objects are there. They can
• 2:02:52
  Speaker 1: see the radio emission. Pinning down the physical properties precisely
• 2:02:56
  Speaker 1: takes longer. The lesson embedded in this is that any
• 2:03:00
  Speaker 1: figure given for the largest known jet structure should be
• 2:03:03
  Speaker 1: understood as provisional. The list of candidates is sitting in
• 2:03:07
  Speaker 1: existing survey data right now. Some of those candidates will
• 2:03:10
  Speaker 1: turn out to be projection effects or measurement artifacts. Others
• 2:03:15
  Speaker 1: will hold up. A few will be larger than anything
• 2:03:18
  Speaker 1: currently confirmed. What this means practically for the science is
• 2:03:22
  Speaker 1: that the cosmological models being built to account for Porphyrian
• 2:03:26
  Speaker 1: scale feedback are already being stressed before those models are finished.
• 2:03:31
  Speaker 1: If giant jets were not rare in the early universe
• 2:03:34
  Speaker 1: but common, then every simulation of galaxy formation and large-scale
• 2:03:40
  Speaker 1: structure that treats black hole feedback as a local effect
• 2:03:43
  Speaker 1: is missing something. The revision required is not a minor correction.
• 2:03:48
  Speaker 1: It is a structural change to the assumptions baked into
• 2:03:52
  Speaker 1: decades of modeling. That revision is happening now, in real time,
• 2:03:57
  Speaker 1: driven by a string of discoveries that began with Alcyoneus
• 2:04:01
  Speaker 1: two years before Porphyrian and has not stopped since. The
• 2:04:05
  Speaker 1: record keeps moving not because individual astronomers are getting cleverer,
• 2:04:10
  Speaker 1: but because the instruments are finally sensitive enough to see
• 2:04:14
  Speaker 1: a population of objects that was always out there, always enormous,
• 2:04:19
  Speaker 1: and always invisible to previous generations of sky surveys. Step
• 2:04:24
  Speaker 1: back from the numbers for a moment and look at
• 2:04:26
  Speaker 1: what this whole thing actually means. Before Perferion, the working
• 2:04:31
  Speaker 1: assumption in extragalactic astronomy was fairly clean. Black holes shaped
• 2:04:36
  Speaker 1: their host galaxies. Powerful ones shaped their galaxy clusters. That
• 2:04:41
  Speaker 1: was roughly the boundary of their influence, and it was
• 2:04:44
  Speaker 1: already enormous by any human measure. Porphyrian erased that boundary.
• 2:04:50
  Speaker 1: A single black hole, sitting at the center of a
• 2:04:53
  Speaker 1: galaxy ten times the mass of the Milky Way, produced
• 2:04:57
  Speaker 1: jets that crossed the filaments of the cosmic web itself.
• 2:05:01
  Speaker 1: Not the neighborhood. Not the cluster. The web. the large-scale
• 2:05:06
  Speaker 1: architecture of the universe. That is the revision that Porphyrian
• 2:05:10
  Speaker 1: forced onto the table, and it is not a small one.
• 2:05:14
  Speaker 1: What made this discovery land differently than a typical record-breaking
• 2:05:18
  Speaker 1: announcement was what it implied about everything we had not
• 2:05:21
  Speaker 1: yet found. Porphyrian was not sitting alone in a category
• 2:05:25
  Speaker 1: of one. Within months, TXS 0033 plus 252 came in
• 2:05:29
  Speaker 1: slightly larger. Before Porphyrian, Alcyoneus had held the record. Both
• 2:05:38
  Speaker 1: of those structures came from the same survey, within two
• 2:05:41
  Speaker 1: years of each other. That pattern is not noise. That
• 2:05:45
  Speaker 1: is a population revealing itself. LOFAR opened a frequency window
• 2:05:50
  Speaker 1: that previous radio telescopes could not match. And inside that window,
• 2:05:55
  Speaker 1: giants had been waiting for decades to be counted. Astronomers
• 2:06:00
  Speaker 1: are now working through the assumption that jets at this
• 2:06:03
  Speaker 1: scale were not rare aberrations in the early universe. They
• 2:06:07
  Speaker 1: may have been common, common enough to have shaped which
• 2:06:10
  Speaker 1: galaxies grew, which ones stalled, and where the filaments of
• 2:06:14
  Speaker 1: the cosmic web ended up drawing their lines. This matters
• 2:06:18
  Speaker 1: in a very specific physical sense. When a jet 23
• 2:06:22
  Speaker 1: million light years long pumps energy into the surrounding gas,
• 2:06:26
  Speaker 1: it heats that gas. Heated gas does not collapse. Gas
• 2:06:31
  Speaker 1: that does not collapse does not form stars. Spread that
• 2:06:35
  Speaker 1: effect across the filaments connecting galaxy clusters, running it for
• 2:06:39
  Speaker 1: hundreds of millions of years, and you are no longer
• 2:06:43
  Speaker 1: talking about the evolution of one galaxy. You are talking
• 2:06:46
  Speaker 1: about the conditions under which entire neighbourhoods of galaxies either
• 2:06:51
  Speaker 1: thrived or didn't. If jets like Porphyrian were operating across
• 2:06:55
  Speaker 1: the early universe in significant numbers, then the distribution of
• 2:06:59
  Speaker 1: galaxies we can see today, the clusters and voids and
• 2:07:03
  Speaker 1: the strange emptiness of certain regions of space, may carry
• 2:07:07
  Speaker 1: the mark of that energy. The cosmic web may not
• 2:07:10
  Speaker 1: be purely gravitational in origin. That is not the story
• 2:07:14
  Speaker 1: astronomers were telling ten years ago. The catalogue will grow.
• 2:07:18
  Speaker 1: That much seems nearly certain. Every improvement in survey sensitivity
• 2:07:24
  Speaker 1: at low radio frequencies will pull more of these structures
• 2:07:28
  Speaker 1: out of the data. Some will be smaller than Porphyrian.
• 2:07:32
  Speaker 1: Some may be larger. The question of where the actual
• 2:07:35
  Speaker 1: ceiling sits, how large a jet can physically get before
• 2:07:39
  Speaker 1: it loses coherence or runs out of fuel, or simply
• 2:07:43
  Speaker 1: disperses into the surrounding medium, has no clean answer yet.
• 2:07:48
  Speaker 1: The theoretical upper limit is not well constrained. What Porphyrian
• 2:07:52
  Speaker 1: demonstrated is that the previous estimates of that ceiling were
• 2:07:56
  Speaker 1: too low by a significant margin. The models are being revised,
• 2:08:01
  Speaker 1: and they are not done being revised. There is something
• 2:08:04
  Speaker 1: else worth sitting with here. The light from Porphyrian that
• 2:08:08
  Speaker 1: reached Earth in time for Martino A and his team
• 2:08:11
  Speaker 1: to measure it left its source 7.5 billion years ago.
• 2:08:16
  Speaker 1: The universe was roughly half its current age. The filaments
• 2:08:20
  Speaker 1: of the cosmic web were more compressed. The galaxies were younger,
• 2:08:25
  Speaker 1: more gas-rich, more chaotic. That is the moment we are
• 2:08:30
  Speaker 1: seeing when we look at Porphyrion. Not now. Then, the
• 2:08:35
  Speaker 1: host galaxy that produced those jets has had 7.5 billion
• 2:08:39
  Speaker 1: more years of history since that light departed. It has aged.
• 2:08:44
  Speaker 1: It may have merged with other galaxies. The black hole
• 2:08:47
  Speaker 1: at its center may have exhausted its fuel supply and
• 2:08:50
  Speaker 1: gone quiet. The jets themselves may have long since faded,
• 2:08:55
  Speaker 1: their plasma dispersed into the intergalactic medium, their lobes dissolved
• 2:09:00
  Speaker 1: into the background hiss of the cosmos. We cannot know
• 2:09:04
  Speaker 1: any of that for 7.5 billion years. This is not
• 2:09:08
  Speaker 1: a poetic observation. It is a genuine epistemic constraint. Everything
• 2:09:14
  Speaker 1: we know about Porphyrian is a snapshot of something that
• 2:09:17
  Speaker 1: happened before Earth existed, before the Sun existed, at a
• 2:09:22
  Speaker 1: point in cosmic time when the atoms that would eventually
• 2:09:25
  Speaker 1: form this solar system were still scattered across whatever star
• 2:09:29
  Speaker 1: clusters have not yet assembled them. The galaxy we are
• 2:09:32
  Speaker 1: looking at is a fossil. It is a message that
• 2:09:35
  Speaker 1: took longer to arrive than the age of our planet.
• 2:09:39
  Speaker 1: And the message says, black holes can do this. Black
• 2:09:43
  Speaker 1: holes did do this. whether they are still doing it,
• 2:09:46
  Speaker 1: whether the jets are still active, whether the host galaxy
• 2:09:49
  Speaker 1: still has an active nucleus at all. Those are questions
• 2:09:53
  Speaker 1: we simply cannot answer from this distance and this moment
• 2:09:57
  Speaker 1: in time. The field right now is in the middle
• 2:10:00
  Speaker 1: of something. LOFAR's survey is ongoing. Other low frequency instruments
• 2:10:05
  Speaker 1: are being developed. Each pass over the sky with greater
• 2:10:09
  Speaker 1: sensitivity will add new objects to the list. Some researchers
• 2:10:13
  Speaker 1: think that when the full catalogue is assembled, jets at
• 2:10:17
  Speaker 1: megaparsec scales will turn out to have been a defining
• 2:10:20
  Speaker 1: feature of the early universe, not an exception but a norm.
• 2:10:25
  Speaker 1: That would mean the universe was, at a certain epoch,
• 2:10:29
  Speaker 1: threaded through with structures like Porphyrion on a scale we
• 2:10:32
  Speaker 1: have barely begun to map. The reckoning with that possibility
• 2:10:36
  Speaker 1: has started, but it is far from finished. Whatever the
• 2:10:40
  Speaker 1: host galaxy of Porphyrian looks like today, in the universe
• 2:10:44
  Speaker 1: as it exists in this moment, the light carrying that
• 2:10:47
  Speaker 1: information is still in transit. It has been crossing space
• 2:10:51
  Speaker 1: since before the Earth formed. It will not arrive for
• 2:10:55
  Speaker 1: another 7.5 billion years. The jets are out there, invisible
• 2:11:01
  Speaker 1: to us, doing whatever they are doing 7.5 billion years later,
• 2:11:06
  Speaker 1: and the news is still on its way.