WEBVTT

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<v Speaker 1>Welcome to Bedtime Astronomy. Explore the wonders of the cosmos

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<v Speaker 1>with our soothing Bedtime Astronomy podcast. Each episode offers a

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<v Speaker 1>gentle journey through the stars, planets, and beyond, perfect for

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<v Speaker 1>unwinding after a long day. Let's travel through the mysteries

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<v Speaker 1>of the universe as you drift off into a peaceful

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<v Speaker 1>slumber under the night sky.

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<v Speaker 2>Imagine opening like a photo album of the universe when

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<v Speaker 2>it was just a toddler.

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<v Speaker 3>Oh, that's a great way to picture it, right, Like.

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<v Speaker 2>You would intuitively expect to see just complete chaos, absolutely,

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<v Speaker 2>just random, messy infant galaxies scattered completely haphazardly in the void,

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<v Speaker 2>like oblivious to one another, just trying to ignite their

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<v Speaker 2>first stars.

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<v Speaker 3>Yeah, just doing their own thing in isolation exactly.

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<v Speaker 2>But recently astronomers developed the optical precision to actually look

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<v Speaker 2>back twelve point six billion years into that exact epoch.

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<v Speaker 3>And they definitely didn't find chaos, No.

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<v Speaker 2>They didn't. They found these sprawling, highly structured, interconnected metropolis incredible.

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<v Speaker 2>And these structures were already dictating exactly how fast those

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<v Speaker 2>infant galaxies would grow, how they would physically shape themselves,

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<v Speaker 2>and like ultimately how they would die. Yeah, we're essentially

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<v Speaker 2>looking at the exact moment the cosmos began playing the

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<v Speaker 2>nurture card, but on a galactic scale.

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<v Speaker 3>Right, And that's huge because the prevailing assumption in cosmology

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<v Speaker 3>for a very long time was that in the early universe,

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<v Speaker 3>specifically that era around one point two billion years after

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<v Speaker 3>the Big Bang, galaxies evolved almost entirely through secular processes.

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<v Speaker 2>Which means what just internal stuff.

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<v Speaker 3>Exactly, meaning their growth was driven by their own internal mass,

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<v Speaker 3>their own gas reservoirs, and just their isolated gravitational dynamics.

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<v Speaker 2>So totally the nature side of the equation, right, You're.

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<v Speaker 3>Born with a certain amount of gas and you just

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<v Speaker 3>build stars until you run out, got it. So finding

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<v Speaker 3>these highlight evolved dense environments acting as like architectural constraints

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<v Speaker 3>so early on, it completely upends our timeline of how

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<v Speaker 3>structures formed because we've.

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<v Speaker 2>Always known that in our current era, you know, the

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<v Speaker 2>mature universe, galaxies are absolutely dominated by their environments, oh

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<v Speaker 2>without a doubt. Like you look at massive structures like

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<v Speaker 2>the Coma cluster which has thousands of galaxies, and it's

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<v Speaker 2>obvious that gravity has corralled them together into these huge

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<v Speaker 2>metropolises of light and hot gas.

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<v Speaker 3>Right. But the assumption was always that this clustering and

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<v Speaker 3>you know, the environmental effects that come with it, took

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<v Speaker 3>billions of years to mature.

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<v Speaker 2>We assumed it took time for the cosmic web to

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<v Speaker 2>tighten its grip.

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<v Speaker 3>Exactly, and that timeline constraint was largely based on the

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<v Speaker 3>sheer scale of the distances.

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<v Speaker 2>Involved and cosmic expansion, right.

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<v Speaker 3>Yeah, the mechanics of expansion, the expansion of space acts

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<v Speaker 3>as this persistent counter force to gravitational collapse.

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<v Speaker 2>It's like a tug of war.

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<v Speaker 3>That is the perfect analogy to form a massive galaxy

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<v Speaker 3>cluster has to win a tug of war against the

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<v Speaker 3>hubble flow.

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<v Speaker 2>The underlying expansion of space itself.

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<v Speaker 3>Right, And on the absolute largest scales, the expansion always wins.

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<v Speaker 3>Space is pulling apart faster than gravity can pull it together.

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<v Speaker 3>But on localized scales, On localized scales, if a region

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<v Speaker 3>has a high enough initial density, its gravitational self attraction

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<v Speaker 3>can actually halt that local expansion. It fights back and wins, Yeah,

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<v Speaker 3>and it causes the whole region to collapse inward. We

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<v Speaker 3>actually call this critical threshold the turnaround radius.

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<v Speaker 2>Okay, so to understand how these environments shaped early galaxies,

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<v Speaker 2>we need to look at the seeds of these modern

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<v Speaker 2>massive clusters, the protoclusters, right, the protoclusters, And if a

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<v Speaker 2>protocluster is essentially a localized region that successfully overcame the

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<v Speaker 2>hubble flow, it must have started with a pretty significant advantage.

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<v Speaker 3>Oh. Absolutely, it had to be an overdensity that was

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<v Speaker 3>baked into the universe from the very beginning, just.

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<v Speaker 2>Like a heavier pocket of space.

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<v Speaker 3>Basically, Yeah, those primordial over densities are the crucial starting

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<v Speaker 3>point because right after the Big Bang, matter was distributed

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<v Speaker 3>with almost perfect uniformity, almost perfect almost, but there are

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<v Speaker 3>these quantum fluctuations in that incredibly dense early state, and

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<v Speaker 3>during cosmic inflation, those microscopic variations were stretched out to

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<v Speaker 3>macroscopic scales.

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<v Speaker 2>Leaving behind these slight variations in density.

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<v Speaker 3>Right and over the first few hundred million years, dark matter,

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<v Speaker 3>which doesn't interact with light so it can collapse much

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<v Speaker 3>earlier than regular gas, began to pool into these slightly

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<v Speaker 3>denser regions.

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<v Speaker 2>Forming like the invisible scaffolding of.

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<v Speaker 3>The universe exactly the dark matter halos. Wow, and these

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<v Speaker 3>dark matter halos serve as the deep gravitational wells that

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<v Speaker 3>anchor literally everything else. As they grew, their gravity pulled

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<v Speaker 3>in the primordial hydrogen and helium.

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<v Speaker 2>Gas, and that gas compresses, cools, and ignites to form

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<v Speaker 2>the first stars.

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<v Speaker 3>And infant galaxies. Yes, so a protocluster is really just

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<v Speaker 3>a vast, sprawling network of these early dark matter halos

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<v Speaker 3>connected by filaments of.

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<v Speaker 2>Gas, just slowly drawing together towards this inevitable massive gravitational collapse.

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<v Speaker 3>Right, and within those dense collapsing regions we see the

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<v Speaker 3>onset of this environmental effect.

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<v Speaker 2>Because in modern galaxy clusters, we know that environment is

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<v Speaker 2>incredibly hostile.

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<v Speaker 3>That's brutal.

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<v Speaker 2>Like if a galaxy falls into a modern cluster, it

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<v Speaker 2>doesn't just join the group peacefully, right, it gets fundamentally altered.

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<v Speaker 3>Yeah, it's violently changed. We see these isolated field galaxies

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<v Speaker 3>as beautiful, gas rich star forming spirals like our Milky Way,

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<v Speaker 3>exactly like the Milky Way, but the galaxies trapped inside

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<v Speaker 3>massive clusters, they're often massive ellipticals, entirely devoid of cold gas.

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<v Speaker 2>Completely incapable of forming new stars. Right.

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<v Speaker 3>Astronomers call it the classic red and dead classification.

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<v Speaker 2>Which sounds so bleak. But what actually causes a galaxy

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<v Speaker 2>to become red and dead when it falls into a

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<v Speaker 2>modern cluster.

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<v Speaker 3>Well, the mechanics driving it are thermodynamically really complex, because

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<v Speaker 3>space within a cluster is not a vacuum.

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<v Speaker 2>It's not empty, not at all.

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<v Speaker 3>The immense gravitational pull of the entire cluster accelerates all

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<v Speaker 3>this infalling gas to tremendous velocities, and.

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<v Speaker 2>As it collides.

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<v Speaker 3>As it collides, it shock heats to millions of degrees.

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<v Speaker 3>It forms what we call the intracluster medium, or the ICM.

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<v Speaker 3>So it's a plasma, a superheated plasma. It's actually so

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<v Speaker 3>hot it emits primarily an X rays.

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<v Speaker 2>Okay, So when a beautiful gas rich spiral galaxy plunges

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<v Speaker 2>into this modern cluster, it's not flying through empty space now,

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<v Speaker 2>it's literally slamming into a wall of superheated plasma at

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<v Speaker 2>thousands of kilometers per second.

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<v Speaker 3>Yeah, and the fluid dynamics of that collision are just

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<v Speaker 3>devastating for the galaxy. I can imagine it experiences extreme

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<v Speaker 3>ram pressure. The static pressure of the hot ICM basically

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<v Speaker 3>acts like a hurricane force headwind, and it physically strips

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<v Speaker 3>the cold star forming gas right out of the galactic.

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<v Speaker 2>Disk, just blows it away.

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<v Speaker 3>Yeah, trailing it behind the galaxy like the tail of

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<v Speaker 3>a comet. And without that cold gas reservoir, star formation

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<v Speaker 3>ceases almost immediately.

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<v Speaker 2>It's just shut off completely. Yeah.

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<v Speaker 3>And furthermore, the galaxy undergoes this process we call strangulation

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<v Speaker 3>or starvation.

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<v Speaker 2>Oh, which also sounds terrible.

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<v Speaker 3>It is the extended halo of hot gas that would

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<v Speaker 3>normally cool down and feed future star formation is also

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<v Speaker 3>stripped away.

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<v Speaker 2>So it loses its current gas and its future supply.

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<v Speaker 3>Exactly. The galaxy is left with only its existing stars,

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<v Speaker 3>which just slowly age, turn red, and eventually die out.

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<v Speaker 2>But see that brings up a massive physical contradiction when

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<v Speaker 2>we talk about the early universe. It really does, because

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<v Speaker 2>if this environmental effect relies on this incredibly dense, superheated

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<v Speaker 2>plasma to act as a hurricane wind, how could that

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<v Speaker 2>effect possibly exist only one point two billion years after

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<v Speaker 2>the Big Bang?

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<v Speaker 3>Right?

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<v Speaker 2>I mean a protocluster by definition hasn't fully collapsed yet.

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<v Speaker 3>Right Exactly, the dark matter halos are still merging.

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<v Speaker 2>The gas hasn't had billions of years to shock heat

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<v Speaker 2>to those extreme X ray temperatures.

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<v Speaker 3>You've highlighted the exact theoretical tension that made this specific

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<v Speaker 3>era so critical to observe.

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<v Speaker 2>Because the plasma shouldn't be there yet.

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<v Speaker 3>Right, the classical mechanisms we just talked about, the ram pressure, stripping,

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<v Speaker 3>the shock heating, they require a mature.

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<v Speaker 2>Settled cluster, a finished product.

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<v Speaker 3>Yeah, a protocluster at that early etpoch what we call

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<v Speaker 3>redshift four or five is basically a sprawling, unfinished construction site.

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<v Speaker 2>The gas is just streaming in along filaments.

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<v Speaker 3>It isn't a static, superheated bath yet. So if we

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<v Speaker 3>observe environmental effects altering the physical structure of galaxies in

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<v Speaker 3>a protocluster, which we did, which we did, it implies

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<v Speaker 3>that the mechanisms of cosmic nurture operate through entirely different

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<v Speaker 3>physics in the early universe compared to today, probably.

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<v Speaker 2>More accretion driven, right like feeding, instead of stripping.

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<v Speaker 3>Exactly, it forces us to ask whether the early environment

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<v Speaker 3>acts as a weapon that strips a galaxy or as

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<v Speaker 3>a hyper efficient feeding tube that alters how it grows.

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<v Speaker 2>But investigating that requires observational data that is frankly, notoriously

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<v Speaker 2>difficult to capture.

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<v Speaker 3>Extremely difficult because we aren't.

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<v Speaker 2>Just looking for one faint object. We are looking for

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<v Speaker 2>a sprawling, diffuse web of faint objects spread across a

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<v Speaker 2>massive volume.

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<v Speaker 3>Of space, seen as they were twelve point six billion

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<v Speaker 3>years ago.

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<v Speaker 2>Yeah, you can't just point a standard telescope at a blank

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<v Speaker 2>patch of sky and hope to recognize a protocluster.

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<v Speaker 3>Now, the observation challenge is huge. It's twofold, really. First,

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<v Speaker 3>the intrinsic faintness of objects at that distance means you

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<v Speaker 3>need an enormous light collecting area, a massive mirror, a

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<v Speaker 3>massive primary mirror. And second, protoclusters are not compact.

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<v Speaker 2>Because the universe expanded, right.

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<v Speaker 3>The universe has expanded so much since that light was emitted.

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<v Speaker 3>A single protocluster from that epoch spans an enormous angular

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<v Speaker 3>size on the night sky today.

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<v Speaker 2>So if you use a telescope with high magnification but

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<v Speaker 2>a tiny field of view.

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<v Speaker 3>You might see one or two galaxies, but you completely

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<v Speaker 3>miss the forest for the trees, You'd never recognize the

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<v Speaker 3>underlying macro structure.

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<v Speaker 2>Which is exactly why astronomers needed an instrument like the

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<v Speaker 2>subru telescope in Hawaii, Yes, specifically utilizing its hyper suprimecam

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<v Speaker 2>or HSC.

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<v Speaker 3>That camera is incredible.

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<v Speaker 2>It's an engineering marvel is designed specifically for wide field surveys.

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<v Speaker 2>It lets researchers map vast swaths of the deep universe simultaneously.

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<v Speaker 3>But even with a massive field of view, looking at

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<v Speaker 3>visible light from that era is completely useless.

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<v Speaker 2>Right, because of redshift. The ultraviolet and visible light emitted

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<v Speaker 2>by those early stars has been physically stretched by the

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<v Speaker 2>expansion of space over twelve point six billion years.

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<v Speaker 3>Yeah, the cosmological redshift is the defining hurdle of high

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<v Speaker 3>redshift astronomy. Space itself is expanding, and as a photon

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<v Speaker 3>traverses that expanding space, its wavelength is physically stretched out.

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<v Speaker 2>So a photon emitted in the ultraviolet by a hot

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<v Speaker 2>young star in the early universe.

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<v Speaker 3>Will arrive at Earth billions of year years later with

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<v Speaker 3>its wavelength stretched all the way into the red or

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<v Speaker 3>infrared part of the spectrum.

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<v Speaker 2>Right, So, if we want to trace the skeletal structure

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<v Speaker 2>of a protocluster, we can't look for just the broad

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<v Speaker 2>spectrum of starlight.

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<v Speaker 3>It's two faint and smeared out exactly.

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<v Speaker 2>We need a specific, highly concentrated signal that survives that

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<v Speaker 2>cosmic stretching, we need a tracer.

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<v Speaker 3>And in cosmology, the ultimate tracer for early star formation

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<v Speaker 3>is the Liman alpha emission line.

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<v Speaker 2>Let's break that down, because the physics underlying Liman alpha

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<v Speaker 2>emission is just so cool. It relies on the fundamental

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<v Speaker 2>quantum mechanics of the hydrogen atom.

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<v Speaker 3>Right, yes, and hydrogen, being the primordial building block of

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<v Speaker 3>the cosmos, was overwhelmingly abundant back then. It was everywhere

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<v Speaker 3>exactly so, when a young massive galaxy undergoes a starburst phase,

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<v Speaker 3>it synthesizes populations of incredibly hot massive stars, the O

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<v Speaker 3>and B type stars.

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<v Speaker 2>And to be clear for everyone, these aren't stars like

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<v Speaker 2>our son oh in it at all. These are stellar behemoths.

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<v Speaker 2>They burn at furious temperatures, and they exhaust their nuclear

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<v Speaker 2>fuel in a matter of millions of years rather than billions.

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<v Speaker 3>Yeah, they live fast and die young. And because they

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<v Speaker 3>burn so hot, the peak of their radiation sits deep

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<v Speaker 3>in the extreme ultraviolet.

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<v Speaker 2>They're essentially cosmic floodlights.

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<v Speaker 3>That is exactly what. They are blasting, high energy, ionizing

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<v Speaker 3>radiation into the surrounding.

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<v Speaker 2>Gas, and that surrounding gas is thick with neutral hydrogen.

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<v Speaker 3>Right, So, When a high energy, extreme ultraviolet photon from

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<v Speaker 3>one of these massive stars collides with the neutral hydrogen atom.

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<v Speaker 2>It transfers its energy to the atom's single electron.

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<v Speaker 3>Yes, and in the quantum mechanical model of the atom,

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<v Speaker 3>electrons occupy specific quantized energy levels. They can't just be anywhere, No,

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<v Speaker 3>they have defined orbits. So the incoming photon provides enough

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<v Speaker 3>energy to excite the electron from its ground state, the

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<v Speaker 3>lowest energy level and equals one up to a higher

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<v Speaker 3>energy orbital.

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<v Speaker 2>But quantum systems inherently seek their lowest possible energy state, right, Yeah,

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<v Speaker 2>the universe absolutely abhors an excited electron.

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<v Speaker 3>Really does. It can't maintain that precarious higher orbit, so.

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<v Speaker 2>It drops back down almost instantaneously.

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<v Speaker 3>Right, But energy must be conserved. When the electron transitions

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<v Speaker 3>from that first excited state and equals to back down

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<v Speaker 3>to the ground state, it has to release the exact

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<v Speaker 3>quantum of energy it originally absorbed.

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<v Speaker 2>And that energy is released as a single photon exactly.

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<v Speaker 3>And because the energy difference between those two specific orbitals

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<v Speaker 3>in a hydrogen atom is an absolute, unchanging physical constant.

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<v Speaker 2>The emitted photon always has the exact same.

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<v Speaker 3>Wavelength one hundred and twenty one point six nanometers.

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<v Speaker 2>Deep in the ultraviolet. Yes, so you have millions of

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<v Speaker 2>these massive stars acting as engines pumping extreme UV radiation

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<v Speaker 2>into the surrounding hydrogen clouds.

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<v Speaker 3>And the hydrogen clouds respond by fluorescently glowing at this

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<v Speaker 3>one highly specific wavelength.

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<v Speaker 2>It basically turns the entire galaxy into a blazing cosmic

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<v Speaker 2>neon sign.

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<v Speaker 3>It's exactly how it acts, flashing open for business making stars.

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<v Speaker 2>I love that that is otherwise incredibly difficult to observe.

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<v Speaker 2>These galaxies are broadcasting this brilliant, unmistakable signal, tied directly

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<v Speaker 2>to the furious birth of new stars.

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<v Speaker 3>And galaxies identified by the specific signature are appropriately called

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<v Speaker 3>Lyman alpha emitters because the submission line is intrinsically so

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<v Speaker 3>bright it acts as a beacon.

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<v Speaker 2>Let's just pinpoint intense star formation across immense distances, right.

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<v Speaker 3>However, actually capturing that one hundred and twenty one point

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<v Speaker 3>six nanometer photon from Earth requires incredibly precise interference filters.

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<v Speaker 2>Because of the red shift we discussed earlier. The photon

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<v Speaker 2>leaves the galaxy at one hundred and twenty one point

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<v Speaker 2>six nanometers, but as it travels for twelve point six

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<v Speaker 2>billion years through expanding space, that wavelength stretches.

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<v Speaker 3>Yeah, But the beauty of it is we can calculate

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<v Speaker 3>the exact red shift for the specific epoch we want to.

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<v Speaker 2>Observe because MathWorks.

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<v Speaker 3>MathWorks. The era of twelve point six billion years ago

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<v Speaker 3>corresponds roughly to a redshift of z equals four point

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<v Speaker 3>five to five. Okay, and we know mathematically exactly how

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<v Speaker 3>much a one hundred and twenty one point six nanimeter

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<v Speaker 3>wavelength will be stretched by a red shift of that magnitude.

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<v Speaker 2>It pushes the wavelength entirely out of the ultraviolet right.

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<v Speaker 3>Yes, through the visible blue and green, and lands it

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<v Speaker 3>squarely in the longer red wavelengths of the optical spectrum.

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<v Speaker 2>So astronomers design a custom piece of glass, a narrow

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<v Speaker 2>band filter that physically blocks out the entire electromagnetic spectrum

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<v Speaker 2>except for that one mathematically predicted stretched out wavelength.

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<v Speaker 3>It's a bespoke filter.

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<v Speaker 2>And they place us in front of the hypersuprime cam,

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<v Speaker 2>and they just stare at a massive patch of the sky.

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<v Speaker 3>Right. They aren't looking at stars in our galaxy or

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<v Speaker 3>even normal galaxies in the background.

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<v Speaker 2>They are basically wearing specialized thermal goggles that's.

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<v Speaker 3>A great analogy, goggles that only let them see the

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<v Speaker 3>specific glow of Liman alpha mitters from exactly twelve point

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<v Speaker 3>six billion years ago.

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<v Speaker 2>It's a technique of extraordinary precision.

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<v Speaker 3>It really is. By utilizing these narrow band filters on

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<v Speaker 3>wide field imagers, you essentially take a highly specific slice

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<v Speaker 3>of the universe at one exact moment in cosmic time.

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<v Speaker 2>You're just mapping the distribution of these glowing beacons.

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<v Speaker 3>Yeah, and if the universe were truly unorganized at that stage,

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<v Speaker 3>you would expect to see a relatively uniform, random scattering

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<v Speaker 3>of Lineman alpha emitters across the field of view.

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<v Speaker 2>Just dots randomly everywhere. Right, But that is the exact

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<v Speaker 2>opposite of what the SUBRU data revealed, totally the opposite.

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<v Speaker 2>When they mapped this specific epoch, they found an astonishing

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<v Speaker 2>concentration of these emitters. They located a massive, highly structured protocluster.

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<v Speaker 3>And they named it the Locktac protocluster.

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<v Speaker 2>Which is such an amazing discovery.

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<v Speaker 3>The identification of the Locktac protocluster is a landmark observation,

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<v Speaker 3>mainly because of its profound morphological complexity.

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<v Speaker 2>Right, because the researchers didn't just find a singular, dense

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<v Speaker 2>knot of galaxies. The mapping revealed this expansive, multi component architecture.

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<v Speaker 2>It was highly structured, and the name itself provides a

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<v Speaker 2>perfect geological metaphor for the structure. It's named after Locktac

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<v Speaker 2>Lake in northeastern.

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<v Speaker 3>India, right in Manipur.

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<v Speaker 2>Yeah, and that lake is famous for its fumnus.

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<v Speaker 3>The floating islands.

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<v Speaker 2>Exactly, these massive, circular, floating islands of organic matter and vegetation.

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<v Speaker 2>Some of them are large enough to support entire localized

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<v Speaker 2>ecosystems like people live on them.

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<v Speaker 3>Wow.

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<v Speaker 2>But they are all floating within and inextricably linked to

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<v Speaker 2>this one singular aquatic system of the lake, and the.

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<v Speaker 3>Mapping of the protocluster mirrors that topology perfectly.

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<v Speaker 2>It really does. The narrow band data revealed four distinct,

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<v Speaker 2>intensely dense subclusters.

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<v Speaker 3>Four separate nodes of hyperactive star formation.

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<v Speaker 2>And these nodes are physically separated by vast distances across

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<v Speaker 2>the early cosmic web. Yet the kinematic data and the

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<v Speaker 2>spatial distribution confirmed they are absolutely gravitationally bound.

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<v Speaker 3>They are four massive islands floating within a shared unseen

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<v Speaker 3>ocean of dark matter.

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<v Speaker 2>It totally validates the bottom up model of hierarchical structure

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<v Speaker 2>formation on a gro and scale. We are looking at

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<v Speaker 2>the fundamental building blocks of a future supercluster before they

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<v Speaker 2>have consolidated. Right.

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<v Speaker 3>Ronaldo Leastrom, the lead author of this study from the

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<v Speaker 3>National Astronomical Observatory of Japan, accurately describe these nodes as

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<v Speaker 3>the construction sites of the most massive structures in the

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<v Speaker 3>present day universe.

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<v Speaker 2>Construction sites. It's so appropriate because it highlights the dynamic,

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<v Speaker 2>unfinished nature of the whole system.

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<v Speaker 3>Very unfinished. In the billions of years following this twelve

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<v Speaker 3>point six billion year old snapshot, the profound mass of

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<v Speaker 3>that shared dark matter halo would act as a massive

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<v Speaker 3>gravitational funnel.

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<v Speaker 2>So those four separate islands.

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<v Speaker 3>They're locked in an inexorable inward spiral, destined to crash

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<v Speaker 3>through the process of dynamical friction, where massive objects lose

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<v Speaker 3>orbital energy as they move through a background of smaller

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<v Speaker 3>particles and dark matter. Their orbits will decay to slow

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<v Speaker 3>down and fall in Exactly, they will eventually fall toward

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<v Speaker 3>the bury center of the system.

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<v Speaker 2>And the eventual collisions between these four nodes would be

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<v Speaker 2>unfathomably violent, truly cataclysmic as those individual subclusters merge. The

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<v Speaker 2>dark matter halos intertwine, but the baryonic matter, the gas,

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<v Speaker 2>and the galaxies slams together.

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<v Speaker 3>Yeah, and those mergers would trigger massive shock waves through

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<v Speaker 3>the newly forming intracluster medium.

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<v Speaker 2>Which would incite even more starbursts before eventually heating the

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<v Speaker 2>gas to the point where star formation is permanently quenched.

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<v Speaker 3>Exactly what we discussed earlier. The Looctac protocluster is definitively

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<v Speaker 3>destined to become one of the monolithic spherical X ray

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<v Speaker 3>emitting superclusters we see in the local universe today.

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<v Speaker 2>So finding this structure provided the perfect laboratory. It proved

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<v Speaker 2>that complex multi noode environments existed extremely early in cosmic history.

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<v Speaker 3>But just establishing the presence of the environment is only

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<v Speaker 3>the prerequisite, right.

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00:19:51.839 --> 00:19:54.960
<v Speaker 2>Right, The main question was is this environment actually doing anything?

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<v Speaker 3>Yes? The primary scientific objective was to determine if this,

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<v Speaker 3>the sprawling, interconnected environment, was actively altering the evolutionary pathways

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<v Speaker 3>of the individual galaxies residing within it.

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00:20:06.759 --> 00:20:09.559
<v Speaker 2>Like did living in one of these four dense islands

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<v Speaker 2>actually change a galaxy's physical structure compared to a galaxy

389
00:20:13.440 --> 00:20:15.160
<v Speaker 2>just growing up in complete isolation.

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00:20:15.599 --> 00:20:18.799
<v Speaker 3>And to answer that, the wide field survey capabilities of

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00:20:18.799 --> 00:20:20.680
<v Speaker 3>the Subaru telescope were no longer.

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<v Speaker 2>Sufficient because Subru is designed to find the city.

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<v Speaker 3>Right, to understand the architecture of the individual buildings within

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00:20:26.720 --> 00:20:29.799
<v Speaker 3>the city, you need unprecedented spatial resolution.

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00:20:30.000 --> 00:20:30.720
<v Speaker 2>You have to zoom in.

396
00:20:30.920 --> 00:20:34.000
<v Speaker 3>You have to transition from wide field mapping to deep

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00:20:34.240 --> 00:20:36.359
<v Speaker 3>targeted observations.

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00:20:35.799 --> 00:20:39.240
<v Speaker 2>Which necessitates space based observatories exactly.

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00:20:39.559 --> 00:20:43.119
<v Speaker 3>The research team employed a multi wavelength approach, combining the

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00:20:43.200 --> 00:20:46.759
<v Speaker 3>high resolution visible light capabilities of the Hubble Space Telescope

401
00:20:47.079 --> 00:20:51.200
<v Speaker 3>with the revolutionary infrared sensitivity of the James Web Space.

402
00:20:51.000 --> 00:20:54.799
<v Speaker 2>Telescope GWST, doing what it does best, and the methodology

403
00:20:54.799 --> 00:20:57.680
<v Speaker 2>here relies on using different wavelengths of light to isolate

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00:20:57.720 --> 00:20:59.559
<v Speaker 2>different physical components of the galaxies.

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00:20:59.640 --> 00:21:04.680
<v Speaker 3>Right, Yeah, They performed a massive comparative analysis. They analyzed

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00:21:04.680 --> 00:21:07.960
<v Speaker 3>the galaxies deeply embedded inside the dense nodes of the

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00:21:08.039 --> 00:21:12.480
<v Speaker 3>Locktac protocluster city dwellers, and they compare them directly to

408
00:21:12.759 --> 00:21:15.880
<v Speaker 3>field galaxies, galaxies from the exact same red shift, the

409
00:21:15.920 --> 00:21:19.759
<v Speaker 3>exact same twelve point six billion year old epoch, but

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00:21:19.880 --> 00:21:23.440
<v Speaker 3>located in low density, isolated regions of the cosmic.

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00:21:23.119 --> 00:21:24.599
<v Speaker 2>Web rural galaxies.

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00:21:24.759 --> 00:21:28.079
<v Speaker 3>Exactly. It is the ultimate controlled experiment for the nature

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00:21:28.200 --> 00:21:31.000
<v Speaker 3>versus nurture debate and astrophysics.

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00:21:30.440 --> 00:21:35.000
<v Speaker 2>Because by isolating the epoch you completely remove time as

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00:21:35.039 --> 00:21:37.799
<v Speaker 2>a variable. They're the exact same age, right.

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00:21:37.599 --> 00:21:41.200
<v Speaker 3>The only major variable altering their evolutionary state should be

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00:21:41.240 --> 00:21:42.880
<v Speaker 3>the local density of their environment.

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00:21:43.160 --> 00:21:45.920
<v Speaker 2>So they scrutinized the physical morphology of these two groups

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00:21:45.920 --> 00:21:49.640
<v Speaker 2>of galaxies across two distinct spectral regimes, right, the rest

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00:21:49.680 --> 00:21:51.799
<v Speaker 2>frame ultraviolet and the rest frame optical.

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00:21:51.920 --> 00:21:54.559
<v Speaker 3>Yes, let's break down the physical significance of those two

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00:21:54.599 --> 00:21:55.400
<v Speaker 3>spectral regimes.

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00:21:55.480 --> 00:21:55.920
<v Speaker 2>Let's do it.

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00:21:56.240 --> 00:21:59.240
<v Speaker 3>The rest frame ultraviolet light, which we observe today red

425
00:21:59.279 --> 00:22:02.319
<v Speaker 3>shifted into the visible or near infrared, acts as a

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00:22:02.359 --> 00:22:05.440
<v Speaker 3>direct tracer for active, ongoing star formation.

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00:22:05.839 --> 00:22:09.000
<v Speaker 2>As we established with the Liman alpha mechanics, UV radiation

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00:22:09.119 --> 00:22:11.200
<v Speaker 2>is dominated by the most massive.

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00:22:11.240 --> 00:22:14.240
<v Speaker 3>Hottest stars, right the O and B types.

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00:22:14.160 --> 00:22:16.960
<v Speaker 2>And because those stars have lifetimes of only a few

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00:22:17.000 --> 00:22:21.400
<v Speaker 2>million years, any UV light we detect must be coming

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00:22:21.400 --> 00:22:24.319
<v Speaker 2>from stars that were born almost exactly the moment the

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00:22:24.400 --> 00:22:25.160
<v Speaker 2>light was emitted.

434
00:22:25.279 --> 00:22:30.000
<v Speaker 3>Exactly. Ultraviolet emission provides an instantaneous pulse check of the galaxy.

435
00:22:30.480 --> 00:22:34.400
<v Speaker 3>It delineates the exact regions where giant molecular clouds are

436
00:22:34.440 --> 00:22:37.680
<v Speaker 3>actively collapsing to form new stellar populations right now.

437
00:22:37.720 --> 00:22:41.240
<v Speaker 2>Okay, So when the researchers analyzed the spatial extent of

438
00:22:41.279 --> 00:22:44.920
<v Speaker 2>the ultraviolet emission, basically measuring the physical size of the

439
00:22:44.920 --> 00:22:48.200
<v Speaker 2>star forming cores, what did they find?

440
00:22:48.359 --> 00:22:52.359
<v Speaker 3>They found a remarkable parody. They were the same, statistically indistinguishable,

441
00:22:52.599 --> 00:22:55.799
<v Speaker 3>whether a galaxy was deeply embedded in the chaotic, dense

442
00:22:55.920 --> 00:22:59.799
<v Speaker 3>environment of the Loctac protocluster or floating completely alone in

443
00:22:59.799 --> 00:23:00.759
<v Speaker 3>the cosmic voids.

444
00:23:00.839 --> 00:23:02.240
<v Speaker 2>The active nurseries looked identical.

445
00:23:02.440 --> 00:23:05.480
<v Speaker 3>Yes, the physical size of their central star forming engines

446
00:23:05.559 --> 00:23:08.000
<v Speaker 3>was the same. The environment did not appear to be

447
00:23:08.039 --> 00:23:11.279
<v Speaker 3>altering the spatial distribution of current star formation in the core.

448
00:23:11.640 --> 00:23:15.079
<v Speaker 2>So if the investigation had just concluded there, if they

449
00:23:15.160 --> 00:23:18.359
<v Speaker 2>only had the ultraviolet data, you might actually conclude that

450
00:23:18.400 --> 00:23:21.119
<v Speaker 2>the early environment had no structural impact at all.

451
00:23:21.160 --> 00:23:24.920
<v Speaker 3>You would you might erroneously conclude that nature entirely dominated

452
00:23:25.039 --> 00:23:26.480
<v Speaker 3>nurture in the early universe.

453
00:23:26.640 --> 00:23:28.799
<v Speaker 2>But the rest frame optical data.

454
00:23:28.680 --> 00:23:34.559
<v Speaker 3>Yes, captured meticulously by Jawst's near infrared camera. It revealed

455
00:23:34.680 --> 00:23:37.680
<v Speaker 3>a drastically different reality.

456
00:23:37.400 --> 00:23:40.000
<v Speaker 2>Because the optical light, which has been redshifted deep into

457
00:23:40.000 --> 00:23:44.599
<v Speaker 2>the infrared where jawst excels, doesn't trace the massive, short

458
00:23:44.599 --> 00:23:45.519
<v Speaker 2>lived hot stars.

459
00:23:45.640 --> 00:23:49.200
<v Speaker 3>No. No, it traces the older, cooler, lower mass stars,

460
00:23:49.400 --> 00:23:51.839
<v Speaker 3>the K and M type dwarfs and giants.

461
00:23:51.440 --> 00:23:53.759
<v Speaker 2>The stars that live for billions of years.

462
00:23:53.559 --> 00:23:57.720
<v Speaker 3>Right Therefore, they represent the accumulated history of the galaxy.

463
00:23:58.079 --> 00:24:01.519
<v Speaker 3>The rest frame optical emission maps the stellar mass distribution

464
00:24:01.640 --> 00:24:04.400
<v Speaker 3>that has already been assembled over the galaxy's entire lifetime

465
00:24:04.480 --> 00:24:05.079
<v Speaker 3>up to that point.

466
00:24:05.240 --> 00:24:08.599
<v Speaker 2>It provides the structural footprint of the established galaxy, independent

467
00:24:08.640 --> 00:24:11.799
<v Speaker 2>of wherever the current transient bursts of new star formation

468
00:24:11.880 --> 00:24:13.240
<v Speaker 2>happened to be a correct exact so I like to

469
00:24:13.240 --> 00:24:16.200
<v Speaker 2>think about it like looking at modern cities. The UV

470
00:24:16.400 --> 00:24:19.319
<v Speaker 2>light shows us the bustling downtown district where all the

471
00:24:19.359 --> 00:24:21.559
<v Speaker 2>new frantic construction is happening right now.

472
00:24:21.720 --> 00:24:23.440
<v Speaker 3>That's a perfect way to visualize it.

473
00:24:23.559 --> 00:24:27.839
<v Speaker 2>But the optical light shows us the sprawling suburbs, the

474
00:24:27.920 --> 00:24:31.440
<v Speaker 2>historical footprint of the city's growth over time. Yes, and

475
00:24:31.480 --> 00:24:34.480
<v Speaker 2>when they compared the optical footprints the suburbs of the

476
00:24:34.480 --> 00:24:38.039
<v Speaker 2>cluster galaxies to the isolated field galaxies.

477
00:24:37.599 --> 00:24:39.400
<v Speaker 3>The parody vanished entirely.

478
00:24:39.559 --> 00:24:41.039
<v Speaker 2>The divergence was profound.

479
00:24:41.160 --> 00:24:44.880
<v Speaker 3>The data explicitly demonstrated that the galaxies residing within the

480
00:24:44.920 --> 00:24:48.759
<v Speaker 3>dense nodes of the Locktac protocluster were on average one

481
00:24:48.799 --> 00:24:51.839
<v Speaker 3>point four times larger in their rest frame optical emission

482
00:24:52.039 --> 00:24:53.559
<v Speaker 3>than their isolated counterparts.

483
00:24:54.039 --> 00:24:57.559
<v Speaker 2>A forty percent increase in physical size. That is a

484
00:24:57.640 --> 00:25:01.200
<v Speaker 2>massive structural discrepancy, It really is. So the central downtowns

485
00:25:01.200 --> 00:25:04.640
<v Speaker 2>are exactly the same size, but the established suburbs of

486
00:25:04.680 --> 00:25:08.119
<v Speaker 2>the cluster galaxies have sprawled outward immensely.

487
00:25:08.039 --> 00:25:11.880
<v Speaker 3>Proving definitively that the environment is actively manipulating the physical

488
00:25:12.000 --> 00:25:15.200
<v Speaker 3>architecture of the galaxies, but it's doing so primarily on

489
00:25:15.240 --> 00:25:19.440
<v Speaker 3>the outskirts right leaving the central star forming cores relatively untouched.

490
00:25:19.720 --> 00:25:23.480
<v Speaker 2>This morphological disparity is really the crux of the discovery, isn't.

491
00:25:23.279 --> 00:25:26.920
<v Speaker 3>It Absolutely because it indicates that the mechanisms of environmental

492
00:25:26.920 --> 00:25:30.319
<v Speaker 3>influence in the early universe are fundamentally different from the

493
00:25:30.359 --> 00:25:33.480
<v Speaker 3>gas stripping processes that dominate modern clusters.

494
00:25:33.920 --> 00:25:37.839
<v Speaker 2>Right Because in a mature cluster, the environment strips the

495
00:25:37.880 --> 00:25:41.559
<v Speaker 2>gas and shuts down star formation in the core, but.

496
00:25:41.599 --> 00:25:45.160
<v Speaker 3>In this early protocluster, the environment is rapidly building up

497
00:25:45.160 --> 00:25:48.359
<v Speaker 3>the extended stellar envelope, while the core just continues to

498
00:25:48.400 --> 00:25:49.200
<v Speaker 3>function normally.

499
00:25:49.279 --> 00:25:52.440
<v Speaker 2>Okay, So that requires us to analyze the actual mechanics

500
00:25:52.440 --> 00:25:55.559
<v Speaker 2>of mass assembly in a dense environment, like if the

501
00:25:55.599 --> 00:25:58.640
<v Speaker 2>central engine isn't working any harder than an isolated galaxy,

502
00:25:59.279 --> 00:26:02.079
<v Speaker 2>how is the club uster galaxy building these massive outer

503
00:26:02.200 --> 00:26:03.319
<v Speaker 2>suburbs so rapidly?

504
00:26:03.480 --> 00:26:06.759
<v Speaker 3>It implies the mass isn't being generated internally.

505
00:26:06.319 --> 00:26:08.240
<v Speaker 2>It's being accreted externally.

506
00:26:08.319 --> 00:26:12.400
<v Speaker 3>Yes, and the theoretical frameworks for galaxy formation strongly support

507
00:26:12.440 --> 00:26:16.160
<v Speaker 3>that conclusion. In a high density node like the Locktac protocluster,

508
00:26:16.559 --> 00:26:20.000
<v Speaker 3>a massive central galaxy sits at the nexus of intersecting

509
00:26:20.079 --> 00:26:21.119
<v Speaker 3>dark matter filaments.

510
00:26:21.319 --> 00:26:24.519
<v Speaker 2>These filaments act as cosmic highways exactly.

511
00:26:24.799 --> 00:26:29.079
<v Speaker 3>They channel continuous streams of cold primordial gas directly into

512
00:26:29.119 --> 00:26:31.160
<v Speaker 3>the gravitational well of the galaxy.

513
00:26:31.359 --> 00:26:33.920
<v Speaker 2>This phenomenon is known as cold stream accretion. Right.

514
00:26:34.119 --> 00:26:37.880
<v Speaker 3>Yes, it provides a massive influx of raw material to

515
00:26:37.960 --> 00:26:39.640
<v Speaker 3>the outer regions of the galaxy.

516
00:26:39.880 --> 00:26:42.599
<v Speaker 2>So it's essentially being force fed by the cosmic web.

517
00:26:42.799 --> 00:26:45.799
<v Speaker 3>Yes, but it's not just pristine gas flowing in the

518
00:26:45.839 --> 00:26:49.559
<v Speaker 3>dense environment of a protocluster is crowded with smaller satellite

519
00:26:49.680 --> 00:26:51.400
<v Speaker 3>dor galaxies, right, so.

520
00:26:51.319 --> 00:26:55.200
<v Speaker 2>The frequency of minor mergers in a protocluster environment must

521
00:26:55.240 --> 00:26:57.920
<v Speaker 2>be exponentially higher than in isolated regions.

522
00:26:58.000 --> 00:27:02.000
<v Speaker 3>Oh, incredibly high. The deep gravitational well of the primary

523
00:27:02.000 --> 00:27:05.960
<v Speaker 3>galaxy constantly captures these smaller satellite galaxies.

524
00:27:05.400 --> 00:27:08.359
<v Speaker 2>And as a dwarf galaxy orbits the larger.

525
00:27:08.000 --> 00:27:11.720
<v Speaker 3>Host, gravitational tidal forces begin to shred it. The stars

526
00:27:11.759 --> 00:27:14.599
<v Speaker 3>and gas from the dwarf galaxy are literally stripped away

527
00:27:14.640 --> 00:27:17.839
<v Speaker 3>and deposited into the extended halo of the primary galaxy.

528
00:27:17.920 --> 00:27:20.960
<v Speaker 2>It's a process of violent gravitational cannibalism.

529
00:27:20.480 --> 00:27:24.000
<v Speaker 3>It really is. The primary galaxy isn't necessarily forming all

530
00:27:24.039 --> 00:27:27.160
<v Speaker 3>those older stars in its massive new suburbs. It's stealing

531
00:27:27.200 --> 00:27:28.680
<v Speaker 3>them from its neighbors.

532
00:27:28.400 --> 00:27:29.480
<v Speaker 2>Just ripping them apart.

533
00:27:29.720 --> 00:27:33.640
<v Speaker 3>Yeah. Over millions of years, as it shreds and consumes

534
00:27:33.720 --> 00:27:38.200
<v Speaker 3>multiple satellite galaxies, those accreted stars build up the extended

535
00:27:38.359 --> 00:27:41.640
<v Speaker 3>diffuse optical footprint that GWST detected.

536
00:27:42.200 --> 00:27:45.480
<v Speaker 2>So it's this combination of cold stream accretion along dark

537
00:27:45.519 --> 00:27:49.160
<v Speaker 2>matter filaments and the elevated rate of minor mergers exactly.

538
00:27:49.279 --> 00:27:53.599
<v Speaker 3>It perfectly explains the physical characteristics observed in the Locktac protocluster.

539
00:27:54.000 --> 00:27:57.079
<v Speaker 2>The environment acts as an accelerant from mass assembly.

540
00:27:57.319 --> 00:28:00.440
<v Speaker 3>The galaxies in the dense nodes have preferential acts to

541
00:28:00.440 --> 00:28:02.680
<v Speaker 3>the cosmological buffet, basically.

542
00:28:02.319 --> 00:28:07.200
<v Speaker 2>Allowing them to rapidly assemble extensive stellar envelopes far earlier

543
00:28:07.559 --> 00:28:10.880
<v Speaker 2>than galaxies starved of those resources in the isolated voids.

544
00:28:11.079 --> 00:28:14.079
<v Speaker 3>Right, the ultimate verdict on the nature versus nurture debate

545
00:28:14.200 --> 00:28:17.079
<v Speaker 3>in the early cosmos is unambiguous at this point.

546
00:28:17.200 --> 00:28:20.559
<v Speaker 2>Nurture plays a massive structural role almost from the very beginning.

547
00:28:20.599 --> 00:28:23.720
<v Speaker 3>Absolutely, just one point two billion years after the Big Bang,

548
00:28:23.759 --> 00:28:26.839
<v Speaker 3>which is barely nine percent into the universe's current lifespan,

549
00:28:27.279 --> 00:28:30.640
<v Speaker 3>a galaxy's physical evolution was already deeply dependent on its

550
00:28:30.640 --> 00:28:32.079
<v Speaker 3>cosmological zip code.

551
00:28:32.240 --> 00:28:36.039
<v Speaker 2>You cannot model the early universe assuming galaxies evolved as

552
00:28:36.079 --> 00:28:40.519
<v Speaker 2>isolated islands. They were heavily manipulated by the interconnected ecosystem

553
00:28:40.559 --> 00:28:41.680
<v Speaker 2>they inhabited.

554
00:28:41.519 --> 00:28:45.920
<v Speaker 3>And it forces a necessary paradigm shift in our cosmological simulations.

555
00:28:46.519 --> 00:28:50.759
<v Speaker 3>Theoretical models must prioritize the macro environmental context, even at

556
00:28:50.799 --> 00:28:52.000
<v Speaker 3>extreme redshifts.

557
00:28:52.119 --> 00:28:55.759
<v Speaker 2>The gravitational web, the hydrodynamics of the inflowing gas, the

558
00:28:55.759 --> 00:28:58.759
<v Speaker 2>proximity and kinematics of neighboring dark matter halos.

559
00:28:58.920 --> 00:29:02.559
<v Speaker 3>Right, these are secondary effects that emerge billions of years later.

560
00:29:02.640 --> 00:29:06.240
<v Speaker 3>They are the primary drivers of morphological evolution from day one.

561
00:29:06.400 --> 00:29:10.000
<v Speaker 2>But you know, this accelerated growth model presents a really

562
00:29:10.039 --> 00:29:14.000
<v Speaker 2>fascinating dichotomy to me. How So, Well, if the early

563
00:29:14.079 --> 00:29:17.920
<v Speaker 2>protocluster environment is basically a hyper efficient feeding mechanism that

564
00:29:18.000 --> 00:29:21.759
<v Speaker 2>builds these massive galaxies rapidly, how do we reconcile that

565
00:29:21.799 --> 00:29:24.240
<v Speaker 2>with the eventual fate of these structures? Right? Because we

566
00:29:24.359 --> 00:29:28.200
<v Speaker 2>established earlier that in the modern mature universe, cluster galaxies

567
00:29:28.240 --> 00:29:31.559
<v Speaker 2>are red and dead the environment eventually chokes them. So

568
00:29:31.920 --> 00:29:35.599
<v Speaker 2>does the very process of this rapid environment driven mass

569
00:29:35.599 --> 00:29:40.400
<v Speaker 2>assembly inadvertently seal their fate? Like does the gluttonous growth

570
00:29:40.799 --> 00:29:42.880
<v Speaker 2>trigger the mechanisms of their own destruction?

571
00:29:43.119 --> 00:29:46.519
<v Speaker 3>It does. The thermodynamics of the environment virtually guarantee it.

572
00:29:46.519 --> 00:29:48.240
<v Speaker 2>It's a double aided sword exactly.

573
00:29:48.839 --> 00:29:51.640
<v Speaker 3>In the early epoch, the dominant process is the accretion

574
00:29:51.720 --> 00:29:55.599
<v Speaker 3>of cold gas along the filaments, which fuels the growth. However,

575
00:29:55.680 --> 00:29:59.000
<v Speaker 3>as the protocluster continues to pull in more mass, the

576
00:29:59.000 --> 00:30:03.759
<v Speaker 3>depth of the gravityational potential well increases significantly, and so.

577
00:30:03.759 --> 00:30:07.079
<v Speaker 2>The velocities of the infalling galaxies and gas clouds increase.

578
00:30:07.279 --> 00:30:11.279
<v Speaker 3>And as those velocities increase, the collisions become far more energetic.

579
00:30:11.440 --> 00:30:12.960
<v Speaker 2>The friction intensifies.

580
00:30:13.000 --> 00:30:16.240
<v Speaker 3>Precisely, the kinetic energy of all that infalling matter is

581
00:30:16.279 --> 00:30:19.680
<v Speaker 3>converted into thermal energy through massive shocks.

582
00:30:19.440 --> 00:30:22.720
<v Speaker 2>So the diffuse gas permeating the protocluster begins to heat

583
00:30:22.799 --> 00:30:23.359
<v Speaker 2>up rapidly.

584
00:30:23.559 --> 00:30:27.640
<v Speaker 3>Yes, eventually the temperature of this intercluster medium crosses a

585
00:30:27.680 --> 00:30:30.440
<v Speaker 3>critical threshold. It becomes so hot that it can no

586
00:30:30.519 --> 00:30:33.200
<v Speaker 3>longer condense and cool down to fom molecular clouds.

587
00:30:33.319 --> 00:30:36.640
<v Speaker 2>So the cold streams that were feeding the galaxies are disrupted.

588
00:30:36.359 --> 00:30:39.880
<v Speaker 3>Evaporated by the expanding volume of superheated plasma.

589
00:30:40.039 --> 00:30:42.000
<v Speaker 2>The buffet just closes exactly.

590
00:30:42.400 --> 00:30:45.880
<v Speaker 3>The environ transitions from a feeding tube to a blast.

591
00:30:45.559 --> 00:30:48.599
<v Speaker 2>Furnace, and as that plasma thickens and heats up, the

592
00:30:48.680 --> 00:30:51.440
<v Speaker 2>ram pressure stripping we talked about earlier finally kicks in.

593
00:30:51.680 --> 00:30:55.559
<v Speaker 3>Yeah, The galaxies, which grew so massive and bloated during

594
00:30:55.599 --> 00:30:59.359
<v Speaker 3>the early feeding phase, now find themselves flying through a dense,

595
00:30:59.400 --> 00:31:03.119
<v Speaker 3>hot wind that violently tears away whatever cold gas they

596
00:31:03.119 --> 00:31:03.680
<v Speaker 3>have left.

597
00:31:04.000 --> 00:31:08.480
<v Speaker 2>It is such a profound evolutionary trajectory. And furthermore, the

598
00:31:08.599 --> 00:31:11.680
<v Speaker 2>rapid mass assembly in the early universe often fuels the

599
00:31:11.759 --> 00:31:15.079
<v Speaker 2>rapid growth of the galaxy's central supermassive black hole.

600
00:31:15.160 --> 00:31:18.599
<v Speaker 3>Right, Yes, that's another crucial factor. As massive amounts of

601
00:31:18.640 --> 00:31:22.000
<v Speaker 3>gas funnel into the galactic center, the black hole begins

602
00:31:22.039 --> 00:31:24.799
<v Speaker 3>to accrete matter at a phenomenal rate, becoming an active

603
00:31:24.839 --> 00:31:27.200
<v Speaker 3>galactic nucleus or AGN.

604
00:31:26.839 --> 00:31:29.799
<v Speaker 2>And AGN feedback is perhaps one of the most violent

605
00:31:30.359 --> 00:31:32.319
<v Speaker 2>regulatory mechanisms in the universe.

606
00:31:32.359 --> 00:31:33.880
<v Speaker 3>Oh, without a doubt, we actually.

607
00:31:33.640 --> 00:31:36.559
<v Speaker 2>See this actively happening in other structures from this era,

608
00:31:36.960 --> 00:31:39.119
<v Speaker 2>like the so called spiderweb protoclusters.

609
00:31:39.359 --> 00:31:43.680
<v Speaker 3>The spiderweb protoclusters are exquisite examples of environment driven regulation.

610
00:31:44.000 --> 00:31:45.440
<v Speaker 2>So what exactly happens there?

611
00:31:45.559 --> 00:31:49.559
<v Speaker 3>In these systems? The central supermassive black hole is accreting

612
00:31:49.599 --> 00:31:54.200
<v Speaker 3>matter so voraciously that it generates colossal jets of relativistic

613
00:31:54.240 --> 00:31:56.799
<v Speaker 3>particles in intense radiation, and.

614
00:31:56.720 --> 00:31:59.920
<v Speaker 2>These jets punch out into the surrounding intraclusters.

615
00:32:00.559 --> 00:32:04.079
<v Speaker 3>Right. The energy injected by the AGN is so immense

616
00:32:04.119 --> 00:32:06.519
<v Speaker 3>that it physically blows the cold gas out of the

617
00:32:06.559 --> 00:32:10.920
<v Speaker 3>central galaxy and heats the surrounding environment, effectively halting star

618
00:32:11.039 --> 00:32:14.519
<v Speaker 3>formation not just within the host galaxy but across massive

619
00:32:14.559 --> 00:32:16.160
<v Speaker 3>swaths of the entire cluster.

620
00:32:16.319 --> 00:32:19.039
<v Speaker 2>Wow. So the central black hole essentially acts as a

621
00:32:19.039 --> 00:32:21.319
<v Speaker 2>thermostat for the entire galactic neighborhood.

622
00:32:21.400 --> 00:32:25.079
<v Speaker 3>Exactly. If the environment feeds the galaxy too quickly, the

623
00:32:25.119 --> 00:32:28.160
<v Speaker 3>black hole ignites and violently shuts off the fuel supply

624
00:32:28.279 --> 00:32:28.880
<v Speaker 3>for everyone.

625
00:32:28.960 --> 00:32:30.720
<v Speaker 2>It's a self regulating macrosystem.

626
00:32:30.839 --> 00:32:31.119
<v Speaker 3>Yeah.

627
00:32:31.160 --> 00:32:33.839
<v Speaker 2>And we also see this extreme feedback in the distant

628
00:32:34.200 --> 00:32:37.440
<v Speaker 2>hot dust obscure galaxies or hot dogs, right, the ones

629
00:32:37.440 --> 00:32:38.720
<v Speaker 2>discovered by JAWST.

630
00:32:38.920 --> 00:32:41.799
<v Speaker 3>Yes, the hot dogs represent an extreme phase of this

631
00:32:41.920 --> 00:32:42.920
<v Speaker 3>evolutionary cycle.

632
00:32:42.960 --> 00:32:46.319
<v Speaker 2>They are just incredibly massive, hyper luminous galaxies in the

633
00:32:46.359 --> 00:32:50.960
<v Speaker 2>early universe that are completely enshrouded and thick, obscuring clouds

634
00:32:50.960 --> 00:32:52.039
<v Speaker 2>of dust, and.

635
00:32:52.079 --> 00:32:57.119
<v Speaker 3>The infrared radiation they emit is staggering. Recent kinematic analysis

636
00:32:57.200 --> 00:33:00.440
<v Speaker 3>using JAWST suggests that much of this dust is not

637
00:33:00.519 --> 00:33:03.240
<v Speaker 3>settled in the galactic disc, but is being violently expelled

638
00:33:03.279 --> 00:33:06.119
<v Speaker 3>outward along the polar axis of the galaxy.

639
00:33:05.880 --> 00:33:10.160
<v Speaker 2>Driven by the intense radiation pressure of a buried, hyperactive

640
00:33:10.240 --> 00:33:11.519
<v Speaker 2>supermassive black hole.

641
00:33:11.720 --> 00:33:16.000
<v Speaker 3>Exactly, the central engine is literally blowing the galaxy's raw

642
00:33:16.079 --> 00:33:19.119
<v Speaker 3>building materials out into intergalactic space, and.

643
00:33:19.079 --> 00:33:23.160
<v Speaker 2>That expelled dust and heavy element enriched gas eventually cools

644
00:33:23.200 --> 00:33:27.000
<v Speaker 2>and mixes into the surrounding environment, chemically altering the intracluster

645
00:33:27.079 --> 00:33:28.799
<v Speaker 2>medium For the next generation.

646
00:33:28.519 --> 00:33:32.359
<v Speaker 3>Galaxies, the feedback loops are just endless and deeply intertwined.

647
00:33:32.519 --> 00:33:35.559
<v Speaker 2>Nothing in the universe evolves in pure isolation. The early

648
00:33:35.599 --> 00:33:40.480
<v Speaker 2>cosmos was a chaotic, violent, but fundamentally interconnected thermodynamic.

649
00:33:39.759 --> 00:33:42.920
<v Speaker 3>Ecosystem, and the discovery of the morphological differences in the

650
00:33:42.960 --> 00:33:46.960
<v Speaker 3>Locktac protocluster provides the foundational evidence for that interconnected reality.

651
00:33:47.079 --> 00:33:50.799
<v Speaker 2>However, as robust is the multi wavelength data from subru,

652
00:33:50.960 --> 00:33:55.759
<v Speaker 2>Hubble and JWST is, the Locktac protocluster remains a single,

653
00:33:56.079 --> 00:33:57.640
<v Speaker 2>albeit massive data point.

654
00:33:57.920 --> 00:34:00.079
<v Speaker 3>Right, It's just one structure. To elevate this from a

655
00:34:00.119 --> 00:34:04.799
<v Speaker 3>profound observation of one specific region to an ironclad universal

656
00:34:04.880 --> 00:34:09.440
<v Speaker 3>law of early galaxy formation, the sample size must increase dramatically.

657
00:34:09.840 --> 00:34:12.320
<v Speaker 2>We need to know if the Locktac protocluster was a

658
00:34:12.440 --> 00:34:17.719
<v Speaker 2>unique anomaly like a particularly weird hyperactive neighborhood, or if

659
00:34:17.719 --> 00:34:21.639
<v Speaker 2>this rapid environment driven structural inflation is the standard rule

660
00:34:21.719 --> 00:34:23.800
<v Speaker 2>for all dense environments in the early.

661
00:34:23.679 --> 00:34:27.880
<v Speaker 3>Universe, and that requires mapping and analyzing dozens, if not hundreds,

662
00:34:28.239 --> 00:34:30.480
<v Speaker 3>of these ancient structures, which.

663
00:34:30.239 --> 00:34:33.400
<v Speaker 2>Brings us to the next generation of astronomical instrumentation which

664
00:34:33.440 --> 00:34:36.920
<v Speaker 2>is being brought online specifically to execute that massive survey.

665
00:34:37.079 --> 00:34:40.880
<v Speaker 3>Yes, the suber telescope itself is currently undergoing a transformative

666
00:34:40.960 --> 00:34:43.800
<v Speaker 3>upgrade to its spectrosnopic capabilities.

667
00:34:43.159 --> 00:34:45.840
<v Speaker 2>A prime focus spectrograph right the Udihulit PFS.

668
00:34:45.960 --> 00:34:48.840
<v Speaker 3>Exactly, it will revolutionize our ability to map these early

669
00:34:48.880 --> 00:34:52.960
<v Speaker 3>structures because while the hypersuprime cam can image vast areas

670
00:34:52.960 --> 00:34:56.800
<v Speaker 3>and identify candidates using narrow band filters, the PFS will

671
00:34:56.800 --> 00:35:00.760
<v Speaker 3>allow astronomers to simultaneously capture the detailed spectrum of thousands

672
00:35:00.760 --> 00:35:04.079
<v Speaker 3>of individual objects across a massive field of view.

673
00:35:04.199 --> 00:35:07.880
<v Speaker 2>And spectroscopy is the key to unlocking the kinematics.

674
00:35:07.920 --> 00:35:08.840
<v Speaker 3>It absolutely is.

675
00:35:09.239 --> 00:35:12.400
<v Speaker 2>Instead of just seeing a glowing dot and estimating its

676
00:35:12.440 --> 00:35:15.880
<v Speaker 2>redshift based on a filter, spectroscopy breaks the light down

677
00:35:15.960 --> 00:35:20.639
<v Speaker 2>into its constituent wavelengths, revealing the exact chemical signatures and

678
00:35:20.719 --> 00:35:22.039
<v Speaker 2>the precise velocity of.

679
00:35:21.960 --> 00:35:25.480
<v Speaker 3>The galaxy, so you can measure exactly how fast those

680
00:35:25.599 --> 00:35:29.000
<v Speaker 3>four massive nodes in the Locktac protocluster are moving toward

681
00:35:29.039 --> 00:35:29.440
<v Speaker 3>each other.

682
00:35:29.679 --> 00:35:32.760
<v Speaker 2>It transitions the data from a two dimensional map into

683
00:35:32.760 --> 00:35:36.519
<v Speaker 2>a fully realized three dimensional kinematic model exactly.

684
00:35:37.000 --> 00:35:40.239
<v Speaker 3>Furthermore, the development of the next generation wide field adaptive

685
00:35:40.239 --> 00:35:44.559
<v Speaker 3>optic system, known as Ultimate, will dramatically reduce the blurring

686
00:35:44.559 --> 00:35:48.760
<v Speaker 3>effects of Earth's atmosphere over unprecedentedly large fields of view.

687
00:35:48.960 --> 00:35:52.079
<v Speaker 2>So this will allow ground based observatories to achieve spatial

688
00:35:52.119 --> 00:35:55.880
<v Speaker 2>resolutions that rival space telescopes, but across much larger areas

689
00:35:55.880 --> 00:35:56.239
<v Speaker 2>of the sky.

690
00:35:56.480 --> 00:35:59.719
<v Speaker 3>Right, and the synergy between those massive high resolution ground

691
00:35:59.760 --> 00:36:03.800
<v Speaker 3>serve and the continued targeted infrared supremacy of the James

692
00:36:03.840 --> 00:36:06.800
<v Speaker 3>Web space telescope is going to define the next decade

693
00:36:06.920 --> 00:36:08.519
<v Speaker 3>of observational cosmology.

694
00:36:08.760 --> 00:36:13.119
<v Speaker 2>They will systematically hunt down these ancient construction sites, peer

695
00:36:13.159 --> 00:36:16.199
<v Speaker 2>through the dust, and map the optical footprints of the

696
00:36:16.239 --> 00:36:17.440
<v Speaker 2>galaxies inside them.

697
00:36:17.800 --> 00:36:20.920
<v Speaker 3>And I would heavily bet that the lock Tack mechanics

698
00:36:21.519 --> 00:36:25.239
<v Speaker 3>the rapid environment driven assembly of galactic suburbs will prove

699
00:36:25.280 --> 00:36:26.760
<v Speaker 3>to be the universal standard.

700
00:36:27.119 --> 00:36:31.000
<v Speaker 2>The principles of thermodynamics and gravity strongly suggest you are correct.

701
00:36:31.360 --> 00:36:34.360
<v Speaker 2>I mean the underlying physics of cold stream accretion and

702
00:36:34.480 --> 00:36:37.360
<v Speaker 2>dynamical friction are not localized phenomena.

703
00:36:37.480 --> 00:36:41.000
<v Speaker 3>Now, they are universal mechanics, dictated by the distribution of

704
00:36:41.039 --> 00:36:41.599
<v Speaker 3>dark matter.

705
00:36:41.760 --> 00:36:44.800
<v Speaker 2>From the microscopic quantum fluctuations in the first fractions of

706
00:36:44.840 --> 00:36:48.400
<v Speaker 2>a second to the sprawling multi million light year filaments

707
00:36:48.400 --> 00:36:51.880
<v Speaker 2>of the cosmic web. The architecture of the space adding

708
00:36:52.159 --> 00:36:56.639
<v Speaker 2>a galaxy inhabits fundamentally and unavoidably dictates the structural object

709
00:36:56.639 --> 00:36:57.239
<v Speaker 2>it will become.

710
00:36:57.480 --> 00:37:00.440
<v Speaker 3>It really is a staggering realization about the Maca Hannicks

711
00:37:00.480 --> 00:37:01.239
<v Speaker 3>of the cosmos.

712
00:37:01.440 --> 00:37:04.239
<v Speaker 2>The universe didn't wait billions of years to mature before

713
00:37:04.360 --> 00:37:06.800
<v Speaker 2>enforcing the rules of structure and environment.

714
00:37:06.440 --> 00:37:06.960
<v Speaker 3>Not at all.

715
00:37:07.199 --> 00:37:10.800
<v Speaker 2>Just one point two billion years in, the invisible scaffolding

716
00:37:10.800 --> 00:37:14.880
<v Speaker 2>of dark matter was already acting as an inescapable evolutionary force.

717
00:37:15.440 --> 00:37:17.679
<v Speaker 2>If a galaxy was born in the dense hub of

718
00:37:17.679 --> 00:37:21.639
<v Speaker 2>a protocluster, it was already rapidly pulling in mass, tearing

719
00:37:21.679 --> 00:37:25.199
<v Speaker 2>apart its smaller neighbors, and sprawling outward into a massive

720
00:37:25.239 --> 00:37:29.039
<v Speaker 2>structural footprint, operating under a completely different set of physical

721
00:37:29.119 --> 00:37:32.000
<v Speaker 2>rules than a galaxy born in the isolated voids.

722
00:37:32.280 --> 00:37:35.880
<v Speaker 3>The environmental effect was inextricably woven into the fabric of

723
00:37:35.920 --> 00:37:40.440
<v Speaker 3>galaxy evolution from the earliest conceivable stages of structure formation, and.

724
00:37:40.440 --> 00:37:44.079
<v Speaker 2>There is a profound philosophical resonance in that scientific reality.

725
00:37:44.159 --> 00:37:46.840
<v Speaker 2>There is think about it. We constantly analyze how we

726
00:37:46.880 --> 00:37:50.320
<v Speaker 2>are shaped by our own environments, how our cities are communities,

727
00:37:50.400 --> 00:37:53.480
<v Speaker 2>the resources available in our neighborhoods, and the local structures

728
00:37:53.519 --> 00:37:56.199
<v Speaker 2>we inhabit dictate our growth and our trajectories.

729
00:37:56.320 --> 00:37:59.440
<v Speaker 3>And it turns out the most incomprehensibly massive structures in

730
00:37:59.480 --> 00:38:02.440
<v Speaker 3>the Cosmo are subject to the exact same fundamental rule

731
00:38:02.480 --> 00:38:03.360
<v Speaker 3>of nature.

732
00:38:03.320 --> 00:38:06.400
<v Speaker 2>At every scale of existence, from the microscopic behavior of

733
00:38:06.440 --> 00:38:10.480
<v Speaker 2>excited electrons to the psychological development of humans to the

734
00:38:10.480 --> 00:38:14.960
<v Speaker 2>thermodynamic evolution of entire galaxies. We are all products of

735
00:38:15.000 --> 00:38:16.440
<v Speaker 2>the environments that surround us.

736
00:38:16.920 --> 00:38:19.400
<v Speaker 3>The universe itself is a product of its environment.

737
00:38:19.519 --> 00:38:22.800
<v Speaker 2>It perfectly bridges the gap between the esoteric physics of

738
00:38:22.880 --> 00:38:27.039
<v Speaker 2>early structure formation and our intuitive understanding of interconnected systems.

739
00:38:27.840 --> 00:38:31.079
<v Speaker 2>We are essentially observing the macro scale equivalent of a

740
00:38:31.159 --> 00:38:32.000
<v Speaker 2>universal truth.

741
00:38:32.159 --> 00:38:34.239
<v Speaker 3>It's beautiful, Honestly it is.

742
00:38:34.559 --> 00:38:36.920
<v Speaker 2>I want to leave you the listener, with a final

743
00:38:36.920 --> 00:38:40.639
<v Speaker 2>thought to mull over long after this discussion ends. We

744
00:38:40.679 --> 00:38:44.840
<v Speaker 2>have spent this time detailing how astrophysicists utilize the specific

745
00:38:44.880 --> 00:38:49.039
<v Speaker 2>quantum mechanics of liman alpha emission, massive wide field surveys,

746
00:38:49.320 --> 00:38:52.559
<v Speaker 2>and precision infrared mirrors to look back twelve point six

747
00:38:52.599 --> 00:38:56.239
<v Speaker 2>billion years. They finally developed the exact right filter to

748
00:38:56.280 --> 00:38:59.400
<v Speaker 2>see the invisible scaffolding that was shaping the Luctac protocluster.

749
00:39:00.079 --> 00:39:03.079
<v Speaker 2>They found the neighborhood that was manipulated the galaxies. But

750
00:39:03.239 --> 00:39:06.800
<v Speaker 2>if the absolute largest structures in the early universe were

751
00:39:06.880 --> 00:39:11.760
<v Speaker 2>already silently organizing and shaping their galactic inhabitants just one

752
00:39:11.840 --> 00:39:15.719
<v Speaker 2>point two billion years after the Big Bang, what massive

753
00:39:15.800 --> 00:39:19.440
<v Speaker 2>invisible cosmic structures are currently shaping our own Milky Way

754
00:39:19.480 --> 00:39:20.360
<v Speaker 2>galaxy right now?

755
00:39:20.440 --> 00:39:22.559
<v Speaker 3>Oooh, that's a deep question, right.

756
00:39:22.960 --> 00:39:25.079
<v Speaker 2>We know we are being pulled toward the Great Attractor,

757
00:39:25.239 --> 00:39:27.599
<v Speaker 2>We know we are part of the Laniakia supercluster. But

758
00:39:27.760 --> 00:39:32.159
<v Speaker 2>what vast unseen gravitational forces are dictating our ultimate evolutionary

759
00:39:32.159 --> 00:39:34.960
<v Speaker 2>fate as we fly through the cosmos? Forces that we

760
00:39:35.039 --> 00:39:38.199
<v Speaker 2>simply haven't invented the right mathematical or optical filter to

761
00:39:38.239 --> 00:39:38.679
<v Speaker 2>see yet.

762
00:39:38.800 --> 00:39:41.360
<v Speaker 3>It's a humbling reminder that we are constantly swimming in

763
00:39:41.400 --> 00:39:44.119
<v Speaker 3>an ocean of gravitational dynamics that we are only just

764
00:39:44.199 --> 00:39:45.519
<v Speaker 3>beginning to accurately map.

765
00:39:45.639 --> 00:39:47.840
<v Speaker 2>Keep looking up and keep questioning the empty spaces.