JWST’s Quintet: Five-Galaxy Merger in the Early Universe

<v Speaker 1>Welcome to Bedtime Astronomy. Explore the wonders of the cosmos
<v Speaker 1>with our soothing Bedtime Astronomi podcast. Each episode offers a
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<v Speaker 1>unwinding after a long day. Let's travel through the mysteries
<v Speaker 1>of the universe as you drift off into a peaceful
<v Speaker 1>slumber under the night sky.
<v Speaker 2>Welcome back to the show. We have a fascinating caper
<v Speaker 2>on the desk today and it's one that I've really
<v Speaker 2>been itching to discuss because well, it messes with a
<v Speaker 2>lot of the mental furniture I've arranged about how the
<v Speaker 2>early universe works.
<v Speaker 3>Oh, this one, Yes, the Texas A and M paper
<v Speaker 3>from Nature Astronomy. This is a big one, it really is.
<v Speaker 2>The headline is, you know, catchy something about a cosmic
<v Speaker 2>car crash, which is great, but the actual data, I
<v Speaker 2>think is it's far more disruptive than even that.
<v Speaker 3>Let's on, I agree. We're looking at a structure confirmed
<v Speaker 3>at redshift six point seven one, which is deep. That
<v Speaker 3>is very, very deep into the history of the cosmos.
<v Speaker 2>Exactly for anyone listening. We're talking about a time just
<v Speaker 2>eight hundred million years after the Big Bang. The universe
<v Speaker 2>is what about six percent of its current.
<v Speaker 3>Age, barely an infant.
<v Speaker 2>Right, And usually when we talk about this specific era,
<v Speaker 2>the epoch of realization, sort of the tail end of
<v Speaker 2>the cosmic dawn, we have the standard picture in our heads.
<v Speaker 3>The hierarchical model, yes.
<v Speaker 2>The hierarchical model. We picture these small, irregular, you know,
<v Speaker 2>low metallicity proto galaxies. We picture them pretty much isolated,
<v Speaker 2>struggling to pull in gas, maybe lighting up a few
<v Speaker 2>of those first generation stars. It's supposed to be a
<v Speaker 2>structurally quiet time.
<v Speaker 3>It's a bottom up process, or that's what we thought.
<v Speaker 3>You start with small dark matter halos and they merge,
<v Speaker 3>but slowly you get slightly bigger halos, gas falls in
<v Speaker 3>at cools, and you form these little galaxies. Slow and
<v Speaker 3>steady is or was the operative phrase.
<v Speaker 2>But this new data from the James Webb Space Telescope,
<v Speaker 2>specifically from the JADES survey, seems to have found something
<v Speaker 2>that well, it just completely defies that slow and steady pacing.
<v Speaker 3>It's not a lonely proto galaxy, not even close.
<v Speaker 2>It's a group, a compact group of five galaxies all
<v Speaker 2>tangled up together. They're calling it JWST's quintet.
<v Speaker 3>Which is a lovely nod, of course, to Stephen's quintet, very.
<v Speaker 2>Famous local group of colliding galaxies. Yeah, but finding something
<v Speaker 2>like that today in our cosmic backyard, that's normal. That
<v Speaker 2>makes sense. Finding a structure that complex, involving five distinct
<v Speaker 2>galaxies just eight hundred million years after the starting gun.
<v Speaker 3>That's the anomaly. That's what has everyone buzzing.
<v Speaker 2>So today our mission is to really take this paper apart.
<v Speaker 2>I want to understand the instrument, the spectral analysis that
<v Speaker 2>confirmed this wasn't just some kind of projection effect, And
<v Speaker 2>most importantly, what are the physical implications for things like
<v Speaker 2>galaxy quenching and metal enrichment. Because this isn't just a wow,
<v Speaker 2>look at the pretty picture story.
<v Speaker 3>No, this is a our simulations might need a patch story.
<v Speaker 2>I thought you might say that.
<v Speaker 3>I think that's a fair assessment. It definitely forces us
<v Speaker 3>to recalibrate the timeline for how quickly the universe got heavy,
<v Speaker 3>you know, chemically speaking, and just how quickly it could
<v Speaker 3>build these massive structures.
<v Speaker 2>So let's start at the beginning, the detection itself. Because
<v Speaker 2>in astronomy, you're only as good as your signal. To
<v Speaker 2>noise ratio right.
<v Speaker 3>Always.
<v Speaker 2>This comes from the JADES survey. That's the JWST Advanced
<v Speaker 2>Deep Extragalactic Survey. Now I know the history of these
<v Speaker 2>deep fields. We had the Hubble deep field, the ultra deep.
<v Speaker 3>Field, the extreme deep field, right.
<v Speaker 2>And the basic idea is you point your telescope at
<v Speaker 2>a patch of sky that looks completely black, a tiny
<v Speaker 2>spot the size of a grain of sand, held at
<v Speaker 2>arm's length, and you just stare for hundreds and hundreds
<v Speaker 2>of hours.
<v Speaker 3>You just let the photons trickle in one by one.
<v Speaker 3>And JD's is the spiritual successor to all of that.
<v Speaker 3>But it's using the specific powers of WEB. And the
<v Speaker 3>key difference here isn't just you know, raw sensitivity, although
<v Speaker 3>that's part of it. It's a spectral coverage. WEB is
<v Speaker 3>an infrared machine, which.
<v Speaker 2>Is an absolute pre was it for looking at this
<v Speaker 2>era of the universe?
<v Speaker 3>It is non negotiable, It's the whole ballgame.
<v Speaker 2>Why why is infrared so important here?
<v Speaker 3>Well, it's all about the expansion of the universe at
<v Speaker 3>a red shift of six point seven. The light that
<v Speaker 3>these young hot stars are putting out, the really powerful
<v Speaker 3>ultraviolet light. Things like the Liman alpha line. That light
<v Speaker 3>has been traveling for over thirteen billion years, and over
<v Speaker 3>that time, the universe itself.
<v Speaker 2>Has stretched, so it stretches the wavelength of the light
<v Speaker 2>along with it.
<v Speaker 3>Exactly the UV light gets stretched all the way across
<v Speaker 3>the visible spectrum and deep into the infrared. Hubble could
<v Speaker 3>see the very very beginning of this, but it really
<v Speaker 3>struggled to get the detailed spectroscopy you need to confirm
<v Speaker 3>distances and find out what these things are made of.
<v Speaker 2>So Web's instruments, the near infrared camera and the near
<v Speaker 2>infrared spectrograph, they are literally built for this.
<v Speaker 3>This is their prime directive.
<v Speaker 2>So the lead researchers, doctor Whita Hue and Professor Ksey Popovich,
<v Speaker 2>they're sifting through this JD stata. What are they looking for?
<v Speaker 2>Typically just a single red dot?
<v Speaker 3>Usually, yeah, the classic technique is looking for dropouts.
<v Speaker 2>Okay, what's the dropout?
<v Speaker 3>You look for a galaxy that appears in your longer
<v Speaker 3>wavelength filters, your redder filters, but then it just disappears
<v Speaker 3>in the shorter bluer ones. Why does it disappear Because
<v Speaker 3>the neutral hydrogen gas that filled the early universe acts
<v Speaker 3>like a thick fog. It absorbs pretty much all the
<v Speaker 3>light bluer than a specific wavelength the Lineman break.
<v Speaker 2>So if it's there in one picture but gone in
<v Speaker 2>the next, you know it's really far away.
<v Speaker 3>That's the classic sign. But here they weren't just looking
<v Speaker 3>for a single dot. They found a complex morphology.
<v Speaker 2>A smudge that turned out to be a crowd.
<v Speaker 3>A smudge that turned out to be a crowd. That's
<v Speaker 3>a great way to put it. In the imaging. It
<v Speaker 3>resolved into five distinct clumps of light. They labeled them
<v Speaker 3>ELG one through ELG five. ELG stands for emission line galaxy.
<v Speaker 2>Let's pause on that emission line galaxy, because that term
<v Speaker 2>tells us something really important about the physical state of
<v Speaker 2>these objects. Right, we aren't just seeing the faint, continuous
<v Speaker 2>glow from a bunch of old stars.
<v Speaker 3>No, not at all. Emission lines are the fingerprint of violent,
<v Speaker 3>active star formation ow. So when you have a burst
<v Speaker 3>of star formation, you create these huge, incredibly hot, short
<v Speaker 3>lived stars we call them O and B type stars,
<v Speaker 3>and they pump out its enormous amounts of hard ultraviolet radiation.
<v Speaker 3>That radiation slams into the surrounding clouds of hydrogen and oxygen,
<v Speaker 3>gas and it ionizes them. It rips the electrons off
<v Speaker 3>the atoms. But then when those electrons recombine or they
<v Speaker 3>cascade back down to lower energy levels, they have to
<v Speaker 3>release that energy, and they do it by emitting light,
<v Speaker 3>but only at very specific discrete wavelengths. It's like a
<v Speaker 3>cosmic neon sign.
<v Speaker 2>So seeing strong emission lines in this case, I'd imagine
<v Speaker 2>it's things like doubly ionized oxygen, the oiday line. That's
<v Speaker 2>basically giant sign flashing. We are making stars right now.
<v Speaker 3>It's a sign that the party is in full swing,
<v Speaker 3>a very very loud party.
<v Speaker 2>And the fact that they could spectroscopically separate f I
<v Speaker 2>have distinct sources, all with compatible red shifts. That's the
<v Speaker 2>real smoking gun here.
<v Speaker 3>That's everything. Because if these were just random galaxies at
<v Speaker 3>different distances that happen to line up in the sky
<v Speaker 3>a chance align, a chance alime exactly, then they're red shifts.
<v Speaker 3>There are coordinates in time. Essentially, they would be all
<v Speaker 3>over the place. One might be a red shift two,
<v Speaker 3>another four, another is seven. But these five all clustered
<v Speaker 3>tightly around zequals six point seven to one. They are
<v Speaker 3>true neighbors. They are physically associated.
<v Speaker 2>Okay, so we've established these five galaxies are neighbors. But
<v Speaker 2>neighbor is a very relative term in cosmology. I mean,
<v Speaker 2>Andromeda is are galactic neighbor, but it's two and a
<v Speaker 2>half million light years away. If we collide, it's not
<v Speaker 2>for another four billion years or so, A very fair point.
<v Speaker 2>What kind of spatial separation are we dealing with in
<v Speaker 2>this quintet? How close are they really?
<v Speaker 3>It is extremely compact, I mean shockingly So the projected
<v Speaker 3>separation that we see on the sky implies that all
<v Speaker 3>five of these galaxies are contained within a region that
<v Speaker 3>only about the size of the Milky Way.
<v Speaker 2>Wait, all five of them inside a region the size
<v Speaker 2>of our single galaxy, all five of them. Yeah, So
<v Speaker 2>let me picture this. You take the Milky Way, which
<v Speaker 2>is about one hundred thousand light years across, but instead
<v Speaker 2>of our one big, organized spiral disc, you have five distinct,
<v Speaker 2>chaotic blobs of gas and stars all swarming and crashing
<v Speaker 2>around inside that same volume of space.
<v Speaker 3>That is exactly the picture you should have in your head.
<v Speaker 3>And that density, that proximity is critical because at that closeness,
<v Speaker 3>gravity is completely dominant. You cannot have five galaxies that
<v Speaker 3>close to each other without intense dynamical friction. They are
<v Speaker 3>constantly dragging on each other. They are stripping material from
<v Speaker 3>one another. This isn't some stable, long term configuration. This
<v Speaker 3>is a snapshot of a collapse. It's a system in
<v Speaker 3>the middle of a violent merger.
<v Speaker 2>It's a train wreck in progress of five train wreck. Wow. Okay,
<v Speaker 2>so this brings us to the energetics of the situation.
<v Speaker 2>You mentioned The emission lines tell us that there's a
<v Speaker 2>lot of star formation happening. I have to assume that
<v Speaker 2>when you mash five gas rich galaxies together like this,
<v Speaker 2>the star formation rate, the SFR, just goes through to room.
<v Speaker 3>It creates what we call a starburst. It's a phenomenon
<v Speaker 3>we see in local mergers too. The antenna galaxies are
<v Speaker 3>the classic example. When galaxies collide, the gas clouds don't
<v Speaker 3>just pass through each other like ghosts. The stars mostly do,
<v Speaker 3>but the gas doesn't. The gas clouds slam into each other.
<v Speaker 3>You get these massive shock waves that propagate through the
<v Speaker 3>interstellar medium.
<v Speaker 2>And what do the shockwaves do.
<v Speaker 3>They compress the gas. They dramatically increase its density, which
<v Speaker 3>allows it to overcome its own internal pressure and start
<v Speaker 3>collapsing under its own gravity.
<v Speaker 2>The genes instability.
<v Speaker 3>Precisely, you drop the gas below the genes mass for
<v Speaker 3>a given temperature and density, and boom, you trigger a
<v Speaker 3>wave of star formation.
<v Speaker 2>And now you're multiplying that effect by five interacting bodies.
<v Speaker 3>It's a chain reaction. The researchers on this paper they
<v Speaker 3>calculate the total SFR for this entire system, and the
<v Speaker 3>number is just it's staggering. This quintet is producing new
<v Speaker 3>stars at a rated roughly two hundred and fifty solar
<v Speaker 3>masses per year.
<v Speaker 2>Two hundred and fifty. Okay, let's put that in context
<v Speaker 2>for everyone. The Milky Way, our home galaxy, is a
<v Speaker 2>pretty big, mature spiral galaxy. What's our current rate?
<v Speaker 3>We are We're pretty quiescent, we're settled down. We churn
<v Speaker 3>out maybe one or two solar masses worth of new
<v Speaker 3>stars per year on a good year one or two.
<v Speaker 2>So this system, just eight hundred million years after the
<v Speaker 2>Big Bang, is over one hundred times more active, maybe
<v Speaker 2>two hundred times more active than the modern Milky Way.
<v Speaker 3>Yes, it is a star factory running at two thousand
<v Speaker 3>percent capacity. If the Milky Way is a slow cooking
<v Speaker 3>stew on the back burner. This thing is a flash
<v Speaker 3>fire on full blast.
<v Speaker 2>That's a great analogy.
<v Speaker 3>And that intensity, that's what explains why it's so incredibly
<v Speaker 3>bright in the infrared and why those mission lines are
<v Speaker 3>just screaming at us. It is burning through its fuel
<v Speaker 3>supply at an absolutely breakneck.
<v Speaker 2>Pace, and that touches on a paradox. I really want
<v Speaker 2>to explore in a bit this idea of running out
<v Speaker 2>of fuel. It seems counterintuitive. But before we get there,
<v Speaker 2>I want to talk about the stuff between the galaxies,
<v Speaker 2>because the paper mentions something that I found really visually evocative.
<v Speaker 2>They didn't just see the five bright clumps of the
<v Speaker 2>galaxies themselves, they saw a.
<v Speaker 3>Halo the diffuse emission. Yes, yeah, this is one of
<v Speaker 3>the most significant findings of the whole study.
<v Speaker 2>So there's this glowing gas connecting them. And it wasn't
<v Speaker 2>just hydrogen, was it.
<v Speaker 3>No, that's the kicker. It was enriched. There's spectroscopy revealed
<v Speaker 3>the clear presence of ionized oxygen in this extended halo,
<v Speaker 3>this bridge of gas connecting the galaxies.
<v Speaker 2>Okay, let's go back to high school chemistry for a second,
<v Speaker 2>and stellar nucleosynthesis. The big bang gives us hydrogen, helium,
<v Speaker 2>and a tiny, tiny pinch of lithium.
<v Speaker 3>That's it, full stop, correct. The primordial soup is what
<v Speaker 3>we call metal free in astronomy. A metal is anything
<v Speaker 3>heavier than helium.
<v Speaker 2>So oxygen atomic number eight. It just doesn't exist in
<v Speaker 2>the universe until a star makes it.
<v Speaker 3>Right, Oxygen is synthesized deep in the cores of massive stars.
<v Speaker 3>It's done through helium fusion. The triple alpha process gets
<v Speaker 3>you to carbon, and then capturing another helium nucleus gets
<v Speaker 3>you to oxygen.
<v Speaker 2>Okay, so the star is the factory. But then crucially,
<v Speaker 2>that star has to die.
<v Speaker 3>It has to die a very violent death. It has
<v Speaker 3>to go supernova to disperse that nearly forged oxygen out
<v Speaker 3>of its core and into the interstellar medium, the gas
<v Speaker 3>within the galaxy.
<v Speaker 2>So finding a detectable amount of oxygen at redshifts six
<v Speaker 2>point seven to one tells us two things. First, that
<v Speaker 2>enough massive stars have already lived their short lives and
<v Speaker 2>died to create this heavy element, which.
<v Speaker 3>Implies there was already a rapid cycle of star formation
<v Speaker 3>happening even before this merger event we're seeing.
<v Speaker 2>And second, and this seems like the more profound point
<v Speaker 2>that oxygen isn't just staying neatly inside the galaxies where
<v Speaker 2>it was made. It's out in the void. It's in
<v Speaker 2>the space between the galaxies exactly.
<v Speaker 3>This is direct visual evidence of the enrichment of what
<v Speaker 3>we call the circumcalactic medium or the CGM, maybe even
<v Speaker 3>the intergalact meeting the IgM. The big question then becomes,
<v Speaker 3>how did it get there?
<v Speaker 2>My first thought is galactic winds. We see this in
<v Speaker 2>local starbust galaxies like MAT two, the Cigar galaxy. The
<v Speaker 2>supernova rate is so high that the collective energy from
<v Speaker 2>all those explosions drives a superwind, basically blowing enriched gas
<v Speaker 2>out of the galactic plane.
<v Speaker 3>And that is an excellent candidate, and it's almost certainly
<v Speaker 3>playing a role here. I mean, when you have a
<v Speaker 3>star formation rate of two hundred and fifty solar masses
<v Speaker 3>per year, the amount of feedback you get from supernova
<v Speaker 3>is just tremendous. You are literally blowing the galaxy apart
<v Speaker 3>from the inside.
<v Speaker 2>But the teen's analysis suggests something else is happening here,
<v Speaker 2>either instead of that, or maybe in addition to it.
<v Speaker 3>In addition to it, the geometry of this halo, the
<v Speaker 3>way it seems to form bridges and streamers points to
<v Speaker 3>another powerful mechanism at play. Gravity again, tidle stripping.
<v Speaker 2>Okay, walk us through that mechanism. How does that work?
<v Speaker 3>So imagine just two galaxies passing close to each other.
<v Speaker 3>The gravity of Galaxy A pulls on the near side
<v Speaker 3>of Galaxy Bee more strongly than it pulls on the
<v Speaker 3>far side.
<v Speaker 2>Right, a differential force exactly.
<v Speaker 3>That's the tidal force, and it stretches Galaxy Bee. It
<v Speaker 3>can rip these long streamers of gas and stars out
<v Speaker 3>of the main body of the galaxy. We call them
<v Speaker 3>title tails.
<v Speaker 2>Like the beautiful long tails you see on the antennae
<v Speaker 2>galaxies and the mice galaxies.
<v Speaker 3>Very same. Now take that concept. Instead of two galaxies
<v Speaker 3>in a graceful dance, imagine five galaxies in a chaotic
<v Speaker 3>wash pit. Yeah, the tidal forces are chaotic. They're multidirectional.
<v Speaker 3>You're not just pulling tails. You are churning the gas.
<v Speaker 3>You're ripping it out of the individual gravitational wells of
<v Speaker 3>these little galaxies and flinging it into the shared space
<v Speaker 3>between them.
<v Speaker 2>It's a cosmic blender.
<v Speaker 3>It is a cosmic blender, and this is so crucial
<v Speaker 3>because it shows us exactly how the universe gets seated
<v Speaker 3>with heavy elements. So very early on, we used to
<v Speaker 3>think that enrichment was a slow process that galaxies sort
<v Speaker 3>of held onto their metals for a long time. He
<v Speaker 3>kept them to themselves, they did. But this shows that
<v Speaker 3>these violent merger events are incredibly efficient at for lack
<v Speaker 3>of a better word, polluting the surrounding environment.
<v Speaker 2>Polluting in the best possible way.
<v Speaker 3>Though, the absolute best way.
<v Speaker 2>Because without that specific pollution, you don't get the building
<v Speaker 2>blocks for rocky planets. You don't get silicon, you don't
<v Speaker 2>get iron, you don't get the oxygen we're breathing, you
<v Speaker 2>don't get us.
<v Speaker 3>Precisely, if that oxygen stays locked inside the stars, or
<v Speaker 3>even just inside the galaxy, then the vast spaces of
<v Speaker 3>the intergalactic medium remain pristine hydrogen and helium forever. But
<v Speaker 3>here we are seeing the exact mechanism for spreading the
<v Speaker 3>seeds of life, or at least the seeds of chemical complexity,
<v Speaker 3>very very early in the cosmic timeline.
<v Speaker 2>I want to pivot now to the crisis aspect of
<v Speaker 2>this discovery. We see headlines like this all the time.
<v Speaker 2>You know, web breaks cosmology, the Big Bang is wrong,
<v Speaker 2>and I tend to roll my eyes at those because
<v Speaker 2>usually it's just a small refinement of some error bars.
<v Speaker 2>It's not a crisis.
<v Speaker 3>It's usually hyperbole.
<v Speaker 2>But doctor Popovich, one of the lead authors, used some
<v Speaker 2>pretty strong language here. He explicitly talked about needing to
<v Speaker 2>update the textbooks.
<v Speaker 3>He did, and he is not someone who is prone
<v Speaker 3>to hyperbole. He's a very careful scientist.
<v Speaker 2>So what is it specifically about our standard model of
<v Speaker 2>cosmology LAMB of CDM, that is threatened by this quintet?
<v Speaker 2>Is it the total mass or is it just the timing?
<v Speaker 3>It's the efficiency in the speed of assembly. Look, the
<v Speaker 3>LAMB of CDM model works incredibly well in the largest scales.
<v Speaker 3>It is spectacular. It predicts the cosmic microwave background, the
<v Speaker 3>large scale structure of the universe, the distribution of dark
<v Speaker 3>matter halos. It's a triumph. Well, when you zoom way
<v Speaker 3>in down to the scales of individual galaxies what we
<v Speaker 3>call baryonic physics, the physics of normal matter like gas
<v Speaker 3>and stars, it gets a lot trickier.
<v Speaker 2>Because there are so many feedback loops and messy processes.
<v Speaker 3>So many and the simulations that are based on Lamba
<v Speaker 3>CDM typically predict that really galaxies are small and that
<v Speaker 3>their mergers are mostly pairwise. Galaxy A emerges into Galaxy.
<v Speaker 4>B simple binary collisions right to find a complex group
<v Speaker 4>of five pretty massive, intensely starbursting galaxies, all merging at once,
<v Speaker 4>just eight hundred million years in.
<v Speaker 3>That suggests that structural formation can happen much faster and
<v Speaker 3>more explosively than our sort of vanilla singulations would predict.
<v Speaker 2>So it's not that the underlying theory of gravity or
<v Speaker 2>dark matter is wrong.
<v Speaker 3>Not at all. It just implies that the dark matter
<v Speaker 3>halos in certain very over dense regions of the early
<v Speaker 3>universe might have been collapsing or clustering far more aggressively
<v Speaker 3>than average.
<v Speaker 2>It's like finding a fully built skyscraper in a city
<v Speaker 2>that's only supposed to be laying down the foundations.
<v Speaker 3>That's a perfect analogy. Or maybe finding a construction crew
<v Speaker 3>that is working twenty four to seven with three shifts
<v Speaker 3>when you thought they only worked on weekends. It tells
<v Speaker 3>us that the dark Ages didn't just end with the whimper.
<v Speaker 3>They ended with a bang.
<v Speaker 2>The universe woke up and got straight to work, no
<v Speaker 2>waiting around immediately. You know, this connects directly to something
<v Speaker 2>we talked about on the show a few months ago,
<v Speaker 2>another JAST puzzle, the red monsters, these huge quiescent, basically
<v Speaker 2>dead galaxies that Web was finding out like redshift three
<v Speaker 2>or four.
<v Speaker 3>Yes, the impossibly massive quenched galaxies.
<v Speaker 2>Right, they were as big as the Milky Way, but
<v Speaker 2>they had already stopped forming stars completely. And the mystery
<v Speaker 2>was always how do you grow that big and die
<v Speaker 2>that young?
<v Speaker 3>That is the quenching problem in a nice show. In
<v Speaker 3>the local universe, galaxies tend to die slowly. They just
<v Speaker 3>gradually run out of gas over billions of years. But
<v Speaker 3>to have a totally dead galaxy at redshift three a
<v Speaker 3>couple billion years after the Big Bang, you need to
<v Speaker 3>have formed all of its stars incredibly fast and then
<v Speaker 3>shut off the gas supply incredibly fast.
<v Speaker 2>And JWST's quintet, I mean, this feels like the prequel
<v Speaker 2>to that movie.
<v Speaker 3>It is almost certainly the progenitor. It has to be.
<v Speaker 3>Think about the math. Just follow the logic. First, you
<v Speaker 3>have a system that is actively merging five galaxies. That's
<v Speaker 3>how you rapidly build up the stellar maps required to
<v Speaker 3>become a monster. Galaxy.
<v Speaker 2>Hey check that gets you the mass.
<v Speaker 3>Second, you have a star formation rate of two hundred
<v Speaker 3>and fifty solar masses per year. As we said, that
<v Speaker 3>is a completely unsustainable burn rate.
<v Speaker 2>It's a cosmic gas guzzler.
<v Speaker 3>It's the very definition of live fast, die young. There's
<v Speaker 3>a metric we use called the gas depletion time. It's simple.
<v Speaker 3>You just take the total massive gas available for star
<v Speaker 3>formation and you divide it by the star formation rate.
<v Speaker 2>So it tells you how long you have until the
<v Speaker 2>tank is empty exactly.
<v Speaker 3>And when you're a denominator the rate is that high,
<v Speaker 3>your depletion time just plummets. For this system, they estimate
<v Speaker 3>the gas will be used up or blown out in
<v Speaker 3>maybe fifty two one hundred million years.
<v Speaker 2>Which in cosmic terms is a blink of an eye.
<v Speaker 3>It's nothing, it's instantaneous. So this quintet is going to
<v Speaker 3>fuse together, it's going to burn through all its available
<v Speaker 3>gas in one spectacular final fireworks show, and then silence.
<v Speaker 3>The star formation will quench. It'll turn into a massive,
<v Speaker 3>red and dead elliptical galaxy.
<v Speaker 2>And it'll do it by what redshifts six point five?
<v Speaker 2>Maybe red shift six, way earlier than we thought possible.
<v Speaker 3>Exactly, So those impossible dead galaxies we found later on
<v Speaker 3>at red shift three or four, they finally have a
<v Speaker 3>plausible origin story.
<v Speaker 2>They came from impossible mergers like this one happening even earlier.
<v Speaker 3>It closes the loop. It actually makes the whole timeline consistent.
<v Speaker 3>You need these extreme violent events like the quintet to
<v Speaker 3>explain the extreme dead galaxies we see a billion years later.
<v Speaker 3>If the early universe was all slow and steady, those
<v Speaker 3>red monsters just shouldn't exist. But because the early universe
<v Speaker 3>was apparently home to these chaotic mosh pits, it all
<v Speaker 3>makes perfect sense.
<v Speaker 2>I love when the puzzle pieces click together like that.
<v Speaker 2>It's not that the entire model is broken. It's that
<v Speaker 2>we underestimated the variance. We underestimated the extremes at the
<v Speaker 2>edge of the Bell curve.
<v Speaker 3>And that's exactly what a deep survey like JD's is
<v Speaker 3>designed to give us. Volume. When you survey a large
<v Speaker 3>enough patch of the sky deeply enough, you stop seeing
<v Speaker 3>just the average run of the mill galaxies. You start
<v Speaker 3>catching the outliers and the.
<v Speaker 2>Outline are what teach you about the limits of physics.
<v Speaker 3>That's where the new discoveries are so let's.
<v Speaker 2>Talk about the future of this specific observation. The paper
<v Speaker 2>is out, it's published in a major journal, but the
<v Speaker 2>science isn't done right. They aren't finished with this data.
<v Speaker 3>No, not by a long shot.
<v Speaker 2>What's the next step for analyzing ELG one through five?
<v Speaker 2>And they're surrounding halo kinematics.
<v Speaker 3>That is the next great frontier for this object movement.
<v Speaker 2>You want to see how it's all move in.
<v Speaker 3>Right now, we have a beautiful but static two D picture.
<v Speaker 3>We know where the galaxies are in the sky, and
<v Speaker 3>we have a rough idea of their red shift, their distance.
<v Speaker 3>But what we really need to do is map the
<v Speaker 3>precise velocities of the gas and the stars within the system.
<v Speaker 3>We need to see if there are rotation curves, or
<v Speaker 3>measure the velocity dispersion, how fast things are buzzing around randomly.
<v Speaker 2>Why is that so important? Is it to weigh the
<v Speaker 2>whole thing?
<v Speaker 3>It's to weigh the whole thing exactly, and astrophysics masses everything.
<v Speaker 3>But you can't put a galaxy on.
<v Speaker 2>A scale unfortunately not.
<v Speaker 3>So you have to for its mass by watching how
<v Speaker 3>fast other things are orbiting it. If the gas is
<v Speaker 3>whipping around at say, five hundred kilometers per second. You
<v Speaker 3>know there has to be a massive amount of gravity
<v Speaker 3>holding it all together, and.
<v Speaker 2>That gravity is coming mostly from the dark matter, the
<v Speaker 2>invisible scaffolding that holds it all together.
<v Speaker 3>Precisely, by carefully mapping the kinematics of this system, doctor
<v Speaker 3>Hugh and his team can get a really solid estimate
<v Speaker 3>of the mass of the dark matter halo that's hosting
<v Speaker 3>this entire group, and that number is the critical input
<v Speaker 3>for the cosmological simulations.
<v Speaker 2>So if the dark matter halo turns out to be
<v Speaker 2>way too bad, way too early, that.
<v Speaker 3>Is when you might start to sweat a little bit
<v Speaker 3>about the standard model. It puts real tension on how
<v Speaker 3>fast those structures can form.
<v Speaker 2>Okay, so we're waiting to see just how heavy this
<v Speaker 2>thing really is.
<v Speaker 3>Yes, and beyond just this one object, the goal is
<v Speaker 3>always statistics. If they found one quintet in this relatively
<v Speaker 3>small JD's survey field, what does that imply?
<v Speaker 2>Does it mean there are thousands of them across the
<v Speaker 2>entire sky?
<v Speaker 3>That's the cosmic variance question. Did we just get incredibly
<v Speaker 3>lucky and point the telescope at the one weird freak
<v Speaker 3>show in the early.
<v Speaker 2>Universe or is this actually common?
<v Speaker 3>And if it is common, then that has profound implications
<v Speaker 3>for how the entire universe was reionized. These violent starbursting
<v Speaker 3>mergers would be incredibly efficient at punching huge ionized holes
<v Speaker 3>in that neutral hydrogen fog we talked about earlier.
<v Speaker 2>They wouldn't just be little pin pricks of light. They
<v Speaker 2>would be the engines that drove reization.
<v Speaker 3>They could be the primary drivers. Yeah, it paints a
<v Speaker 3>much more dynamic, much more violent picture of that whole era.
<v Speaker 2>It really does. I want to circle back here for
<v Speaker 2>a moment to the listener's perspective. We've been throwing around
<v Speaker 2>a lot of terms, you know, red shift, jade, cgm
<v Speaker 2>en Richmond. But if I'm driving to work right now,
<v Speaker 2>or walking my dog, and I look up at the
<v Speaker 2>blue sky, which is blue because of oxygen and nitrogen.
<v Speaker 2>By the way, why does this matter to me? Why
<v Speaker 2>should I care about five blobs of light colliding thirteen
<v Speaker 2>billion years years ago?
<v Speaker 3>It matters because it's our genealogy. We often think of
<v Speaker 3>the early universe as this alien, foreign place. It's so
<v Speaker 3>far away in space, so long ago in time, it
<v Speaker 3>feels disconnected from us. But the physics happening in that quintet,
<v Speaker 3>the creation of oxygen inside those massive stars, the spreading
<v Speaker 3>of that oxygen by those chaotic title tales. That is
<v Speaker 3>the direct, unbroken precursor to the chemistry of our own
<v Speaker 3>solar system.
<v Speaker 2>We are literally made of that pollution.
<v Speaker 3>We are star stuff, as the saying goes, But more
<v Speaker 3>than that, we are merger stuff. The oxygen that is
<v Speaker 3>in your lungs right now, the iron in your blood,
<v Speaker 3>the silicon in the ground beneath your feet. It didn't
<v Speaker 3>just appear. It was cooked in the cores of stars,
<v Speaker 3>and then it was violently thrown out into the void
<v Speaker 3>by events exactly like this one.
<v Speaker 2>This content isn't just a picture. It's us watching the
<v Speaker 2>universe's industrial revolution.
<v Speaker 3>That's a fantastic way to put it. It's the moment
<v Speaker 3>the universe started mass manufacturing the raw materials needed for complexity,
<v Speaker 3>for planets, for life.
<v Speaker 2>The most stunning part of this discovery is that it
<v Speaker 2>started doing it way way earlier than we ever gave
<v Speaker 2>it credit for.
<v Speaker 3>That is the key takeaway. Yeah, it means the potential
<v Speaker 3>for complex chemistry, and therefore the potential for complex planetary systems,
<v Speaker 3>starts much earlier in the cosmic story than we used
<v Speaker 3>to think.
<v Speaker 2>Now that leads to a pretty provocative final thought. We
<v Speaker 2>usually assume that things like life, or even just the
<v Speaker 2>formation of rocky planets is a late universe phenomenon.
<v Speaker 3>Right, that's the conventional wisdom. You need a few generations
<v Speaker 3>of stars to die to build up enough metallicity in
<v Speaker 3>the gas to form a solid rocky planet.
<v Speaker 2>But if you have these massive violent enrichment events happening
<v Speaker 2>at just eight hundred million years, if you're slinging oxygen
<v Speaker 2>and silicon and iron around the cosmos that early, could
<v Speaker 2>the clock for habitability actually start much much sooner than
<v Speaker 2>we imagine.
<v Speaker 3>It's highly speculative, of course, but it's not impossible. If
<v Speaker 3>you can create these localized pockets of very high metallicity
<v Speaker 3>very early on, you could theoretically form rocky planets around
<v Speaker 3>some of the first population two stars lead But the stage,
<v Speaker 3>the chemical stage for life, might have been set while
<v Speaker 3>the universe was still a toddler.
<v Speaker 2>It kind of reframes the Fermi paradox a little bit,
<v Speaker 2>doesn't it. If the universe has been potentially ready for
<v Speaker 2>life for thirteen billion years, not just say the last
<v Speaker 2>eight or nine, Well, where is everybody?
<v Speaker 3>That is a very deep dive for another.
<v Speaker 2>Day, a very deep dive. Indeed, before we wrap up,
<v Speaker 2>I just want to give proper credit where it's due,
<v Speaker 2>doctor Whee, to Who, doctor Casey Popovich, and the entire
<v Speaker 2>JD's collaboration. It is so easy to see these incredible
<v Speaker 2>images on social media and just scroll past them. It
<v Speaker 2>is but the sheer amount of human ingenuity and engineering
<v Speaker 2>required to park a telescope a million miles from Earth,
<v Speaker 2>keep it colder than the surface of Pluto, and have
<v Speaker 2>it stare at a patch of utter darkness for days
<v Speaker 2>on end just to catch a handful of photons from
<v Speaker 2>the dawn of time.
<v Speaker 3>It's a monumental human achievement, it really is.
<v Speaker 2>And the analysis that follows, teasing out the faint signal
<v Speaker 2>of five interacting galaxies from all the noise from all
<v Speaker 2>the foreground objects, it's just as impressive. It's detective work
<v Speaker 2>at the very edge of reality. Absolutely so, I think
<v Speaker 2>the big takeaway for today is this, the early universe
<v Speaker 2>was not a quiet, lonely, simple place. It was a
<v Speaker 2>construction site. It was messy, it was loud, it was violent,
<v Speaker 2>and it was churning out the very elements of life
<v Speaker 2>at an absolutely furious pace, and we.
<v Speaker 3>Are only just now with web beginning to see it
<v Speaker 3>clearly for the first time.
<v Speaker 2>That is a thrilling thought. We finally opened the door
<v Speaker 2>to that room, and it turns out it's incredibly crowded. Indeed,
<v Speaker 2>thank you so much for breaking this all down with us.
<v Speaker 2>This cosmic car crash has definitely reshaped my view of
<v Speaker 2>the dawn of time.
<v Speaker 3>My pleasure. It's always exciting to look back this.
<v Speaker 2>Far and to you listening. The next time you look
<v Speaker 2>up at a clear, dark night sky, just remember it
<v Speaker 2>looks peaceful now, but you're really looking at the aftermath
<v Speaker 2>of a very, very chaotic beginning. We'll see you on
<v Speaker 2>the next dive. Stay curious, Si,