WEBVTT 1 00:00:03.399 --> 00:00:07.719 Welcome to Bedtime Astronomy. Explore the wonders of the cosmos 2 00:00:07.759 --> 00:00:12.279 with our soothing Bedtime Astronomie podcast. Each episode offers a 3 00:00:12.359 --> 00:00:16.320 gentle journey through the stars, planets, and beyond, perfect for 4 00:00:16.399 --> 00:00:20.239 unwinding after a long day. Let's travel through the mysteries 5 00:00:20.239 --> 00:00:22.440 of the universe as you drift off into a peaceful 6 00:00:22.480 --> 00:00:23.800 slumber under the night sky. 7 00:00:26.960 --> 00:00:29.559 Imagine you walk into a preschool, right, and you see 8 00:00:29.559 --> 00:00:32.679 a group of toddlers, and these toddlers are just, you know, 9 00:00:33.000 --> 00:00:37.799 casually assembling a perfectly functional, high performance Formula one engine. 10 00:00:37.960 --> 00:00:42.000 Oh wow, Yeah, that would be well terrifying, honestly, right. 11 00:00:42.000 --> 00:00:44.399 You wouldn't just be surprised. You would immediately assume that, 12 00:00:44.479 --> 00:00:47.840 like everything you knew about human development, cognitive milestones, and 13 00:00:47.840 --> 00:00:50.560 basic physics was just completely wrong. 14 00:00:50.719 --> 00:00:54.079 You'd be looking at this highly complex finished product in 15 00:00:54.119 --> 00:00:59.399 an environment where honestly, only raw, uncoordinated materials should even exist. 16 00:00:59.560 --> 00:01:03.240 Exactly, and today we are looking at the cosmic equivalent 17 00:01:03.359 --> 00:01:04.840 of that Formula one engine. 18 00:01:04.879 --> 00:01:06.760 It's a massive paradigm shift. 19 00:01:06.519 --> 00:01:08.519 It really is. I mean, we are taking you, the listener, 20 00:01:08.599 --> 00:01:11.359 eleven point five billion years into the past. We're looking 21 00:01:11.400 --> 00:01:13.400 at the universe when it was just a mere toddler 22 00:01:13.760 --> 00:01:15.719 only about two billion years. 23 00:01:15.599 --> 00:01:20.280 Old, which in cosmic terms is practically infancy, right, And. 24 00:01:20.200 --> 00:01:23.519 The object we are examining today is designated EIGHTYF twenty 25 00:01:23.519 --> 00:01:26.359 two point a one or sometimes just eighty F twenty 26 00:01:26.400 --> 00:01:27.040 two point one. 27 00:01:27.200 --> 00:01:28.920 Yeah, both get used in the literature. 28 00:01:29.200 --> 00:01:33.599 And the sheer existence of this galaxy, with its majestic, 29 00:01:33.920 --> 00:01:38.359 highly ordered spiral structure and spinning of these staggering speeds, 30 00:01:38.719 --> 00:01:42.480 it just completely breaks the established timeline of cosmic evolution. 31 00:01:42.319 --> 00:01:44.920 It really does. I mean, the timeline of galaxy formation 32 00:01:45.000 --> 00:01:47.959 has been anchored for decades by this idea called the 33 00:01:48.040 --> 00:01:50.239 hierarchical merging paradigm. 34 00:01:49.799 --> 00:01:52.120 And that's basically the idea that the early universe was 35 00:01:52.200 --> 00:01:54.120 just a chaotic, violent place. 36 00:01:53.959 --> 00:01:58.000 Right right exactly. Early galaxies were expected to be well, irregular, 37 00:01:58.400 --> 00:02:02.799 just clumpy, messy block of gas and young stars smashing together. 38 00:02:02.640 --> 00:02:04.280 Like a cosmic demolition derby. 39 00:02:04.439 --> 00:02:07.680 Yeah, that's a good way to put it. Building a stable, massive, 40 00:02:07.760 --> 00:02:11.360 rotationally supported disc something like our modern Mochy way that 41 00:02:11.439 --> 00:02:13.240 was supposed to take billions of years. 42 00:02:13.039 --> 00:02:16.319 Because it requires slow accretion, violent collisions, and then this 43 00:02:16.800 --> 00:02:18.960 gradual settling of angular momentum. 44 00:02:19.080 --> 00:02:21.960 Right, So we definitely did not expect to find a massive, 45 00:02:22.360 --> 00:02:26.240 beautifully structured pinwheel galaxy sitting right there in the immediate 46 00:02:26.280 --> 00:02:28.520 aftermath of the universe's formative epic. 47 00:02:28.719 --> 00:02:31.360 It's wild eighty F twenty two point a one forces 48 00:02:31.400 --> 00:02:34.039 a total re evaluation of how quickly the universe can 49 00:02:34.120 --> 00:02:35.280 organize mass and energy. 50 00:02:35.560 --> 00:02:39.719 It really shows us that highly sophisticated structures can form 51 00:02:40.120 --> 00:02:41.319 incredibly early on. 52 00:02:41.520 --> 00:02:44.960 Okay, let's unpack this because going from the expectation of 53 00:02:45.039 --> 00:02:49.319 chaotic blobs to discovering a highly ordered, barred spiral in 54 00:02:49.360 --> 00:02:53.039 the Toddler universe, that's a massive shift in our understanding 55 00:02:53.039 --> 00:02:53.479 of physics. 56 00:02:53.560 --> 00:02:54.159 You had shift. 57 00:02:54.280 --> 00:02:56.960 Yeah, But before we get into the structural mechanics of 58 00:02:57.319 --> 00:03:00.800 how ADF twenty two top a one built itself without 59 00:03:00.800 --> 00:03:03.960 being destroyed by collisions, we really need to address why 60 00:03:04.000 --> 00:03:05.439 it took us so long to find it. 61 00:03:05.680 --> 00:03:08.199 That's a great question because it is massive. 62 00:03:08.400 --> 00:03:08.560 Right. 63 00:03:08.680 --> 00:03:11.000 If this thing is so huge, why didn't we see 64 00:03:11.000 --> 00:03:13.240 it earlier? I mean, we've had the Hubble space telescope 65 00:03:13.280 --> 00:03:15.800 staring to the deep field for decades now. 66 00:03:15.840 --> 00:03:18.560 Well, the simple answer is that Hubble was fundamentally blinded 67 00:03:18.599 --> 00:03:20.919 by the very nature of these specific early. 68 00:03:20.719 --> 00:03:24.039 Galaxies, blinded how like by the distance no by dust. 69 00:03:24.280 --> 00:03:26.960 ADF twenty two dot a one falls into a category 70 00:03:27.000 --> 00:03:30.240 we call dusty star forming galaxies or dsfgs. 71 00:03:30.360 --> 00:03:32.080 Ah. Okay, the dust is the key. 72 00:03:32.199 --> 00:03:35.319 Yeah, these are systems undergoing star formation at rates that 73 00:03:35.400 --> 00:03:39.039 are just almost incomprehensible by our local standards. 74 00:03:39.120 --> 00:03:40.639 What kind of rates are we talking about here? 75 00:03:40.759 --> 00:03:44.599 We're talking about hundreds, sometimes even thousands of solar masses 76 00:03:44.759 --> 00:03:47.120 being converted into stars every single year. 77 00:03:47.319 --> 00:03:50.479 Wow. And just for context, the Milky Way produces what 78 00:03:50.680 --> 00:03:52.560 maybe one to three solar masses a. 79 00:03:52.599 --> 00:03:55.840 Year, exactly just a handful. So ADF twenty two dot 80 00:03:55.879 --> 00:03:59.120 a one is an absolute monster in comparison. 81 00:03:59.240 --> 00:04:02.400 But the byprod of all that rampant star formation is 82 00:04:02.400 --> 00:04:05.000 an immense amount of interstellar dust right right. 83 00:04:05.039 --> 00:04:08.360 The massive short lived O and B type stars in 84 00:04:08.400 --> 00:04:13.319 these early galaxies, they basically explode as supernovae very quickly, and. 85 00:04:13.240 --> 00:04:16.879 Those explosions enriched the interstellar medium with heavier elements. 86 00:04:17.000 --> 00:04:20.160 Yeah, and those elements condense into microscopic dust grains. It 87 00:04:20.199 --> 00:04:22.480 creates this incredibly thick cosmic. 88 00:04:22.079 --> 00:04:26.000 Fog, and dust is incredibly efficient at absorbing short wavelength light. 89 00:04:26.079 --> 00:04:28.560 So all that ultraviolet and optical light pouring out of 90 00:04:28.600 --> 00:04:31.399 those young hot stars just hits the dust and scatters. 91 00:04:31.560 --> 00:04:34.560 Right, Because the wavelength of that light is roughly the 92 00:04:34.600 --> 00:04:37.759 same size as the dust grains themselves, it's essentially blocked. 93 00:04:38.279 --> 00:04:41.000 So when Hubble looked at these early epochs, it couldn't 94 00:04:41.000 --> 00:04:44.839 see the underlying stellar architecture at all. Because Hubble is 95 00:04:44.920 --> 00:04:49.040 primarily an optical and near infrared observatory. 96 00:04:48.759 --> 00:04:51.879 Exactly, it's all only the leakage. Hubble would capture a 97 00:04:51.879 --> 00:04:56.879 few irregular, clumpy patches of rest frame ultraviolet light that 98 00:04:56.959 --> 00:04:58.319 just happened to escape. 99 00:04:58.079 --> 00:05:00.839 Through thinner, less dense regions the dust clouds. 100 00:05:00.959 --> 00:05:04.839 Yeah, and this observational bias actually fed the old paradigm perfectly. 101 00:05:04.959 --> 00:05:09.120 Oh, I see. Because astronomers only saw messy, disjointed clumps 102 00:05:09.120 --> 00:05:12.680 of light, they naturally concluded that the galaxies themselves were 103 00:05:12.759 --> 00:05:14.839 messy disjointed clumps. 104 00:05:14.920 --> 00:05:17.439 Right. We were looking at the uneven surface of a 105 00:05:17.480 --> 00:05:20.279 thick fog bank, and just assuming that the terrain underneath 106 00:05:20.360 --> 00:05:21.800 was just as irregular. 107 00:05:21.439 --> 00:05:24.040 That's a brilliant way to picture it. So to pierce 108 00:05:24.079 --> 00:05:26.399 that fog, we needed to move entirely out of the 109 00:05:26.399 --> 00:05:27.439 optical spectrum. 110 00:05:27.480 --> 00:05:31.480 We needed observatories operating at wavelength that simply ignore the dust. 111 00:05:31.480 --> 00:05:34.079 Entirely, which brings us to the pairing of the James 112 00:05:34.079 --> 00:05:39.600 web Space Telescope and ALMA, the Atacoma Large Millimeter submillimeter Array. 113 00:05:39.959 --> 00:05:42.519 This is where the technology finally caught up to the physics. 114 00:05:42.839 --> 00:05:45.079 Let's start with JWST, right. 115 00:05:44.920 --> 00:05:49.519 Because JWST is designed specifically to capture longer wavelength infrared light. 116 00:05:49.879 --> 00:05:53.639 Yeah, and because those infrared waves are physically longer than 117 00:05:53.639 --> 00:05:56.480 the diameter of the cosmic dust grains, the light just 118 00:05:56.519 --> 00:05:57.680 passes right through the fog. 119 00:05:57.839 --> 00:06:01.759 It's like having X ray vision for dust. JWST's near 120 00:06:01.920 --> 00:06:05.040 infrared camera in IRCAM essentially allows us to see the 121 00:06:05.079 --> 00:06:08.639 actual distribution of the older, cooler stars exactly. 122 00:06:08.879 --> 00:06:12.480 It reveals the true structural skeleton of the galaxy. But 123 00:06:12.560 --> 00:06:16.360 while JWST gives us the stellar mass distribution, it doesn't 124 00:06:16.360 --> 00:06:17.480 give us the kinematics. 125 00:06:17.600 --> 00:06:19.680 Right. It shows us where the stars are, but not 126 00:06:19.759 --> 00:06:21.240 how the raw material is moving. 127 00:06:21.480 --> 00:06:24.399 Yeah, and that is where ALME comes in. LMA operates 128 00:06:24.399 --> 00:06:26.079 in the submillimeter regime. 129 00:06:25.959 --> 00:06:30.839 Specifically looking at wavelengths around eight hundred and seventy micrometers 130 00:06:30.839 --> 00:06:32.199 for this object right correct. 131 00:06:32.240 --> 00:06:35.720 At those wavelengths, Alia is passive. It's capturing the thermal 132 00:06:35.759 --> 00:06:38.160 emission of the warm dusk greens themselves. 133 00:06:37.720 --> 00:06:40.319 And it also picks up specific emission lines of cold 134 00:06:40.360 --> 00:06:42.519 molecular gas and ionized atoms. 135 00:06:42.600 --> 00:06:45.240 Right for eightf twenty two dot a one. Al MA 136 00:06:45.519 --> 00:06:48.279 was tuned to track a very specific signature, the fine 137 00:06:48.279 --> 00:06:50.680 structure emission line of ionized carbon. 138 00:06:50.439 --> 00:06:52.480 Also known as the CII emission line. 139 00:06:52.560 --> 00:06:56.399 Yeah, carbon is distributed throughout the interstellar medium of these galaxies. 140 00:06:56.160 --> 00:06:59.279 And when the electrons in these carbon atoms drop from 141 00:06:59.360 --> 00:07:05.160 higher energy state to a lower one, they meet a photon. 142 00:07:04.959 --> 00:07:08.560 Exactly, a photon with a very specific resting wavelength of 143 00:07:08.600 --> 00:07:10.480 about one hundred and fifty eight micrometers. 144 00:07:10.519 --> 00:07:12.879 Wait. I see a major challenge here, though, Okay, what 145 00:07:13.040 --> 00:07:16.439 is it? If JWST is mapping the infrared light from 146 00:07:16.439 --> 00:07:20.839 the stars and ALMA is mapping the submillimeter emission from 147 00:07:20.879 --> 00:07:24.079 the ionized carbon gas, how do we know they are 148 00:07:24.079 --> 00:07:26.360 looking at the exact same physical structure? 149 00:07:26.560 --> 00:07:28.240 Ah, the alignment problem. 150 00:07:28.319 --> 00:07:31.480 Right. In a crowded early universe, a line of sight 151 00:07:31.560 --> 00:07:34.279 could easily pass through a random cloud of gas in 152 00:07:34.319 --> 00:07:36.920 the foreground before hitting a galaxy in the background. 153 00:07:36.959 --> 00:07:38.079 It absolutely could. 154 00:07:38.160 --> 00:07:40.199 So if you just lay the two images on top 155 00:07:40.240 --> 00:07:43.519 of each other, how do you mathematically prove the alignment 156 00:07:43.600 --> 00:07:46.240 is real and not just an optical illusion of the perspective? 157 00:07:46.519 --> 00:07:51.560 That requires really rigorous astrometric calibration. Astronomers don't just blindly 158 00:07:51.600 --> 00:07:52.759 overlay the images. 159 00:07:52.439 --> 00:07:54.199 And hope for the best, okay, So what do they do? 160 00:07:54.319 --> 00:07:56.680 They use a shared reference frame. Typically it's tied to 161 00:07:56.720 --> 00:07:58.839 the International Celestial Reference System. 162 00:07:58.680 --> 00:08:00.839 So they find common points in both images. 163 00:08:01.199 --> 00:08:04.120 Exactly in the fields observed by both telescopes, there are 164 00:08:04.120 --> 00:08:08.639 point sources, usually quasars or well characterized background objects. 165 00:08:08.319 --> 00:08:11.600 And these objects emit strongly in both near infrared and 166 00:08:11.680 --> 00:08:13.040 submillimeter wavelengths. 167 00:08:13.199 --> 00:08:16.600 Right by aligning the absolute coordinates of those known reference 168 00:08:16.639 --> 00:08:20.000 points down to fractions of an arcsecond, you can lock 169 00:08:20.040 --> 00:08:20.959 the two maps together. 170 00:08:21.160 --> 00:08:24.079 The gas from LMA and the stellar light from JWST 171 00:08:24.199 --> 00:08:25.519 are perfectly registered. 172 00:08:25.639 --> 00:08:28.959 Yes, And when that precise astrometric overlay was performed for 173 00:08:29.160 --> 00:08:33.039 eighty F twenty two dot A one, the spatial distribution 174 00:08:33.120 --> 00:08:36.559 of the gas matched the stellar morphology perfectly. 175 00:08:36.399 --> 00:08:39.840 So it definitely wasn't a foreground cloud. The ionized carbon 176 00:08:39.960 --> 00:08:41.759 was dynamically bound to the stellar disc. 177 00:08:42.240 --> 00:08:44.840 It was a single cohesive object, no doubt about it. 178 00:08:44.879 --> 00:08:47.720 And once that alignment is locked, the image that emerges 179 00:08:47.799 --> 00:08:50.399 is just breath taking. We strip away the cosmic fog 180 00:08:50.440 --> 00:08:52.480 and we don't see a blob, no blog at all. 181 00:08:52.559 --> 00:08:57.000 We see a giant, rapidly rotating barred spiral disc. It 182 00:08:57.039 --> 00:09:00.799 has a clear spiral distribution of stars, a central elongated 183 00:09:00.840 --> 00:09:04.320 barlike feature spanning the core, and massive clumpy arms. 184 00:09:04.320 --> 00:09:06.879 That's beautiful. Yeah, but the visual is really only half 185 00:09:06.879 --> 00:09:08.039 the story here, right. 186 00:09:08.120 --> 00:09:11.159 The physical properties are truly defy the models. Let's look 187 00:09:11.159 --> 00:09:14.240 at the numbers. The Snellar disc is roughly twice the 188 00:09:14.279 --> 00:09:17.519 size of typical galaxies from that exact same era right. 189 00:09:17.399 --> 00:09:21.200 At redshift zev round three, and the median stellar mass 190 00:09:21.720 --> 00:09:25.120 sits at a log of m star over msun greater 191 00:09:25.159 --> 00:09:26.039 than ten point eight. 192 00:09:26.399 --> 00:09:29.559 Translating that log rhythmic scale for you listening, we are 193 00:09:29.559 --> 00:09:32.799 looking at a stellar mass well in excess of sixty 194 00:09:33.000 --> 00:09:35.240 billion times the mass of our Sun. 195 00:09:35.440 --> 00:09:37.440 And that is just the mass locked up in the stars. 196 00:09:37.480 --> 00:09:39.879 That's not even accounting for the dark matter halo or 197 00:09:39.919 --> 00:09:41.639 the vast reservoirs of gas. 198 00:09:41.879 --> 00:09:45.399 That's insane for a galaxy to have converted that much 199 00:09:45.480 --> 00:09:49.200 raw material into a stable stellar population just two billion 200 00:09:49.279 --> 00:09:51.720 years after the Big Bang. It places it in a 201 00:09:51.799 --> 00:09:53.600 rare heavyweight class, it really does. 202 00:09:54.039 --> 00:09:57.360 But the mass is just the prerequisite for the real anomaly. 203 00:09:56.960 --> 00:09:59.200 Here, which lies in the kinematics right exactly. 204 00:09:59.399 --> 00:10:02.240 This goes back to Alma and the ionized carbon emission 205 00:10:02.240 --> 00:10:03.519 line we were just talking about. 206 00:10:03.360 --> 00:10:06.879 Because Alima isn't just taking a static picture of the gas, 207 00:10:06.879 --> 00:10:08.919 it's actually measuring the Doppler shift. 208 00:10:09.080 --> 00:10:12.759 Correct, we know the rest wavelength of the CII emission line. 209 00:10:12.840 --> 00:10:15.759 So as Alima observes the disc of EIGHTF twenty two 210 00:10:15.799 --> 00:10:18.679 dot a one, it detects that the wavelength of light 211 00:10:18.759 --> 00:10:21.600 coming from one side of the galaxy is stretched or 212 00:10:21.639 --> 00:10:22.960 red shifted. 213 00:10:22.799 --> 00:10:25.879 Meaning that specific gas is physically moving away from us, 214 00:10:25.919 --> 00:10:26.159 and on. 215 00:10:26.120 --> 00:10:28.799 The opposite side of the disc the wavelength is compressed 216 00:10:29.039 --> 00:10:29.679 or blue. 217 00:10:29.399 --> 00:10:31.759 Shifted, which means the gas is approaching us. Right. 218 00:10:32.159 --> 00:10:34.960 And when you plot these velocities across the spatial plane 219 00:10:34.960 --> 00:10:38.759 of the galaxy, it generates an isovelocity contour. 220 00:10:38.360 --> 00:10:42.080 Map, frequently referred to as a spider diagram. The highly 221 00:10:42.080 --> 00:10:46.720 symmetrical nature of This diagram is the undeniable kinematic signature 222 00:10:46.759 --> 00:10:50.240 of a coherent, cohesive rotating disc. 223 00:10:50.279 --> 00:10:53.480 And the velocity of that rotation is what completely breaks 224 00:10:53.519 --> 00:10:56.879 the models. The Alma data reveals that this massive disc 225 00:10:57.000 --> 00:11:00.120 is spinning at an incredible five hundred and thirty kilometers. 226 00:10:59.679 --> 00:11:01.399 Percon It's moving incredibly fast. 227 00:11:01.480 --> 00:11:05.000 At that speed, the centrifugal force is immense. The outer 228 00:11:05.159 --> 00:11:08.000 edges of this galaxy are moving so fast that they should, 229 00:11:08.039 --> 00:11:11.000 by all rights just be flung out into intergalactic space. 230 00:11:11.080 --> 00:11:12.039 Yeah, they really should be. 231 00:11:12.240 --> 00:11:15.000 So if the buryonic mass, you know, the sixty billion 232 00:11:15.039 --> 00:11:18.399 solar masses of stars plus the gas, isn't enough to 233 00:11:18.399 --> 00:11:21.840 hold it together against that rotational shear, where is the 234 00:11:21.840 --> 00:11:22.840 gravitational anchor? 235 00:11:23.039 --> 00:11:25.440 Well, you have to assume the dark matter fraction here 236 00:11:25.519 --> 00:11:28.679 is incredibly dense to prevent the galaxy from tearing itself apart. 237 00:11:28.799 --> 00:11:31.559 The dark matter halo is the unseen scaffolding. 238 00:11:31.639 --> 00:11:35.159 Absolutely, to maintain stability at a rotational velocity of five 239 00:11:35.240 --> 00:11:38.480 hundred and thirty kilometers per second eightyf twenty two point a, 240 00:11:38.639 --> 00:11:42.279 one must possess a dynamical mass that far exceeds its 241 00:11:42.320 --> 00:11:43.200 buryonic mass. 242 00:11:43.279 --> 00:11:46.600 It's the dark matter providing the deep gravitational well required 243 00:11:46.600 --> 00:11:49.240 to tether all that high velocity gas and stars. 244 00:11:49.320 --> 00:11:52.399 Right, But what is truly anomalous is the dynamical state 245 00:11:52.480 --> 00:11:55.399 of the baryens themselves. How So we quantify it by 246 00:11:55.399 --> 00:11:58.840 something called the V over signa ratio. That's the rotational 247 00:11:58.879 --> 00:12:02.799 velocity V divided by the velocity dispersion sigma. 248 00:12:02.360 --> 00:12:06.399 And velocity dispersion measures the chaotic, random, thermal like motions 249 00:12:06.399 --> 00:12:08.080 of the stars and gas within the system. 250 00:12:08.159 --> 00:12:11.039 Right. Yes, so high velocity dispersion means the orbits of 251 00:12:11.080 --> 00:12:13.559 the stars are highly elliptical, plunging in and out of 252 00:12:13.559 --> 00:12:16.080 the galactic center in totally random orientations. 253 00:12:16.320 --> 00:12:21.000 Okay, So for decades, numerical simulations suggested that massive galaxies 254 00:12:21.000 --> 00:12:23.320 in the early universe would be dispersion. 255 00:12:22.840 --> 00:12:25.799 Supported, exactly because they were supposed to form through those 256 00:12:25.879 --> 00:12:27.200 violent mergers we talked. 257 00:12:27.039 --> 00:12:28.919 About the demolition Derby, Right. 258 00:12:29.120 --> 00:12:31.840 The kinetic energy of those collisions would be pumped into 259 00:12:31.879 --> 00:12:32.960 the random motions of. 260 00:12:32.919 --> 00:12:35.799 The stars, which results in a high sigma and a 261 00:12:35.840 --> 00:12:39.200 low V. They would be puffy, chaotic ellipticals. 262 00:12:39.320 --> 00:12:42.480 But eighty f twenty two dot a one has a 263 00:12:42.639 --> 00:12:45.759 very high V over sigma ratio. It is a rotationally 264 00:12:45.759 --> 00:12:46.559 supported disk. 265 00:12:46.840 --> 00:12:51.000 The ordered coherent spinning far out weighs the chaotic buzzing. 266 00:12:51.279 --> 00:12:53.519 The kinetic energy is highly organized. 267 00:12:53.600 --> 00:12:55.919 It is which forces a massive logical paradox. 268 00:12:55.960 --> 00:12:58.440 Honestly, I was just thinking that if this galaxy has 269 00:12:58.519 --> 00:13:01.639 tens of billions of solar mass of stars, the traditional 270 00:13:01.720 --> 00:13:03.879 rule book says it must have achieved that mass by 271 00:13:03.960 --> 00:13:05.320 consuming other galaxies. 272 00:13:05.399 --> 00:13:08.759 Yeah, hierarchical merging. Small halos of dark matter and gas 273 00:13:08.799 --> 00:13:10.559 crash together to make larger halos. 274 00:13:10.639 --> 00:13:13.919 But major mergers are incredibly violent. If a galaxy half 275 00:13:14.000 --> 00:13:16.480 the size of EIGHTF twenty two but a one slammed 276 00:13:16.519 --> 00:13:20.159 into it, the gravitational tidal forces would completely scramble the 277 00:13:20.240 --> 00:13:21.120 orbits of the stars. 278 00:13:21.440 --> 00:13:25.600 It would completely destroy that delicate, high velocity rotationally supported 279 00:13:25.639 --> 00:13:26.360 spiral disc. 280 00:13:26.559 --> 00:13:30.200 It would just leave behind a dispersion supported scrap peep. So, 281 00:13:30.240 --> 00:13:33.399 how does an object get this massive without getting messy? 282 00:13:33.480 --> 00:13:36.440 We can actually quantify the absence of that messiness using 283 00:13:36.440 --> 00:13:37.759 morphological mathematics. 284 00:13:37.840 --> 00:13:40.720 Okay, so astronomers don't just rely on visual classification. 285 00:13:41.039 --> 00:13:45.279 No, they analyze the light distribution using non parametric metrics, 286 00:13:45.720 --> 00:13:49.000 primarily the cirsic index and the GENM twenty coefficients. 287 00:13:49.080 --> 00:13:52.039 Let's break those down. What is the cirsic profile. 288 00:13:52.200 --> 00:13:54.960 It basically measures how the intensity of a galaxy's light 289 00:13:55.159 --> 00:13:57.440 varies with distance from its center. 290 00:13:57.279 --> 00:13:58.759 So how the brightness fades out. 291 00:13:59.000 --> 00:14:02.480 Yeah, a c index of n equals one describes an 292 00:14:02.480 --> 00:14:05.840 exponential profile, and that is the mathematical signature of a 293 00:14:05.840 --> 00:14:07.080 flat extended disc. 294 00:14:07.240 --> 00:14:09.039 Okay, what about a higher number. 295 00:14:08.799 --> 00:14:12.879 An index of n equals four, known as the devocolur profile, 296 00:14:13.240 --> 00:14:16.600 describes a highly concentrated, steep light distribution. 297 00:14:16.320 --> 00:14:19.879 Which is typical of a massive dispersion supported elliptical galaxy 298 00:14:20.559 --> 00:14:23.200 or a dense central bulge built by mergers. 299 00:14:23.600 --> 00:14:27.440 Right, and when you map the infrared light from JWST 300 00:14:27.639 --> 00:14:30.799 for ADFU two dot a one, it fits the n 301 00:14:30.840 --> 00:14:32.679 equals one exponential profile. 302 00:14:32.960 --> 00:14:36.519 It firmly aligns with a disk profile. It's mathematical proof 303 00:14:36.600 --> 00:14:38.080 of its shape exactly. 304 00:14:38.480 --> 00:14:40.200 Furthermore, you have the gene coefficient. 305 00:14:40.279 --> 00:14:42.519 Wait, isn't that an economics term, like it used to 306 00:14:42.600 --> 00:14:44.120 track wealth inequality? 307 00:14:44.240 --> 00:14:46.840 It is, but in astrophysics it's used to measure the 308 00:14:46.879 --> 00:14:50.200 inequality of pixel slux values in a galaxy image. 309 00:14:50.320 --> 00:14:53.080 Oh that's clever. So a high gene coefficient means the 310 00:14:53.200 --> 00:14:56.320 light is highly concentrated in a few bright pixels. 311 00:14:55.960 --> 00:14:59.960 Yes, which often indicates a dense core or violent localized 312 00:15:00.200 --> 00:15:01.960 starbursts from a recent merger. 313 00:15:02.080 --> 00:15:04.639 Okay, and what is the M twenty part of GENM twenty? 314 00:15:04.840 --> 00:15:07.399 M twenty measures the second order moment of the brightest 315 00:15:07.440 --> 00:15:10.039 twenty percent of the galaxy's pixels. It acts as an 316 00:15:10.039 --> 00:15:11.360 indicator of spatial structure. 317 00:15:11.480 --> 00:15:14.159 So mergers typically produce high Genie and high M twenty 318 00:15:14.240 --> 00:15:17.679 values because the light is unevenly distributed into multiple clumps 319 00:15:17.759 --> 00:15:18.480 or tidle tales. 320 00:15:18.559 --> 00:15:20.799 Right, So by running the pixels through these formulas you 321 00:15:20.879 --> 00:15:22.320 remove human bias entirely. 322 00:15:22.639 --> 00:15:24.639 You aren't just looking at an image and saying, well, 323 00:15:24.679 --> 00:15:27.759 it looks like a disc. You are mathematically proving that 324 00:15:27.799 --> 00:15:32.039 the distribution of mass lacks the localized spikes and tidal 325 00:15:32.120 --> 00:15:35.320 distortions that a major merger would inevitably leave behind. 326 00:15:35.480 --> 00:15:39.159 It classifies cleanly as a late type disc. But as 327 00:15:39.200 --> 00:15:41.519 you said, if it didn't smash its way to sixty 328 00:15:41.559 --> 00:15:44.840 billion solar masses, how did it get so heavy? 329 00:15:45.000 --> 00:15:47.720 Right? Where does the mass come from? If not from collisions? 330 00:15:48.120 --> 00:15:48.879 Smooth accretion? 331 00:15:49.039 --> 00:15:51.080 Smooth accretion? Okay, explain how. 332 00:15:51.000 --> 00:15:55.600 We see that the data from jwst in Lama reveals 333 00:15:55.600 --> 00:15:59.600 a distinct wavelength dependent size trend, and this provides the 334 00:15:59.600 --> 00:16:01.279 finger of its growth mechanism. 335 00:16:01.440 --> 00:16:04.279 Okay, what does a wavelength dependent sized trend actually mean 336 00:16:04.360 --> 00:16:05.080 for the galaxy? 337 00:16:05.240 --> 00:16:08.519 Well, when observed its shorter rest frame wavelengths, which trace 338 00:16:08.720 --> 00:16:12.720 the hot, highly energetic young blue stars, the physical extent 339 00:16:12.759 --> 00:16:14.320 of the galaxy appears much larger. 340 00:16:14.360 --> 00:16:15.919 The effective radius is extended. 341 00:16:16.039 --> 00:16:20.919 Yes. However, when observed at longer wavelengths, which trace the older, cooler, 342 00:16:21.039 --> 00:16:24.879 lower mass stars, the galaxy is significantly more compact, with. 343 00:16:24.799 --> 00:16:27.639 The light concentrated heavily in the central regions, so that 344 00:16:27.679 --> 00:16:30.440 wavelength gradient maps directly to an age gradient. 345 00:16:30.639 --> 00:16:32.399 Exactly, it is inside outgrowth. 346 00:16:32.480 --> 00:16:35.159 The core of the galaxy is the oldest region. It 347 00:16:35.279 --> 00:16:38.399 formed first, and over the past billion years or so, 348 00:16:38.799 --> 00:16:42.000 generations of stars have lived and died there, choking the 349 00:16:42.039 --> 00:16:43.000 center with dust. 350 00:16:43.519 --> 00:16:46.840 But the galaxy isn't just sitting there. It is continuously 351 00:16:46.840 --> 00:16:48.559 adding mass to its outer edges. 352 00:16:48.720 --> 00:16:52.759 The younger bluer light is extended because pristine raw material 353 00:16:52.840 --> 00:16:55.320 is continuously arriving at the periphery of the disc. 354 00:16:55.440 --> 00:16:59.480 Right it rives, cools, condenses, and ignites into fresh rings. 355 00:16:59.480 --> 00:16:59.960 Of new star. 356 00:17:00.440 --> 00:17:04.559 It's expanding its borders outwards smoothly without disrupting the ancient 357 00:17:04.720 --> 00:17:05.599 established core. 358 00:17:05.799 --> 00:17:09.680 This continuous, smooth delivery of gas is basically the only 359 00:17:09.759 --> 00:17:13.680 way to build a massive, rotationally supported disc this early 360 00:17:13.680 --> 00:17:14.400 in the universe. 361 00:17:14.440 --> 00:17:16.960 But a galaxy cannot accrete tens of billions of solar 362 00:17:17.000 --> 00:17:20.039 masses of gas smoothly unless it resides in an environment 363 00:17:20.160 --> 00:17:22.119 capable of providing that supply chain. 364 00:17:22.519 --> 00:17:25.039 That's the key. We have to look beyond the galaxy 365 00:17:25.039 --> 00:17:28.160 itself and examine the broader cosmological scaffolding. 366 00:17:28.400 --> 00:17:31.440 Because EIGHTYF twenty two but A one does not exist 367 00:17:31.559 --> 00:17:34.119 in an isolated void. It is located at the center 368 00:17:34.160 --> 00:17:37.240 of the SSA twenty two protocluster at redshift Z equals 369 00:17:37.240 --> 00:17:38.920 three point zero nine, and. 370 00:17:38.960 --> 00:17:42.319 A protocluster is essentially a massive over density of dark 371 00:17:42.359 --> 00:17:45.880 matter that is in the process of gravitationally collapsing to 372 00:17:45.960 --> 00:17:47.200 form a galaxy. 373 00:17:46.799 --> 00:17:49.640 Cluster, which are the largest bound structures in the universe. 374 00:17:50.160 --> 00:17:52.359 And this SSA twenty two region is. 375 00:17:52.400 --> 00:17:57.160 Extreme, very extreme. The number density of galaxies in this 376 00:17:57.200 --> 00:18:01.839 specific volume of space is over ten times the cosmic average, so. 377 00:18:01.799 --> 00:18:05.240 It's an incredibly crowded neighborhood, but way a crowded neighborhood 378 00:18:05.319 --> 00:18:10.000 usually means more collisions, more hierarchical merging, you'd think so, yes, 379 00:18:10.079 --> 00:18:12.920 So if it's surrounded by other galaxies, how is EIGHTF 380 00:18:13.000 --> 00:18:16.519 twenty two dot a one avoiding the demolition derby and 381 00:18:16.559 --> 00:18:18.400 pulling in pristine gas. 382 00:18:18.240 --> 00:18:20.400 By tapping directly into the cosmic web. 383 00:18:20.480 --> 00:18:23.880 The cosmic web, I love that term, It's very descriptive. 384 00:18:24.039 --> 00:18:28.279 Cosmological simulations demonstrate that dark matter forms a vast three 385 00:18:28.319 --> 00:18:30.119 dimensional filamentary network. 386 00:18:29.839 --> 00:18:32.519 And galaxies and clusters form at the nodes where these 387 00:18:32.519 --> 00:18:34.119 filaments intersect exactly. 388 00:18:34.160 --> 00:18:36.200 Now. For a long time, the dominant theory was that 389 00:18:36.319 --> 00:18:39.400 gas falling into a massive dark matter halo would undergo 390 00:18:39.519 --> 00:18:40.440 shock heating. 391 00:18:40.400 --> 00:18:43.319 Creating a spherical halo of hot gas that would slowly 392 00:18:43.359 --> 00:18:45.279 cool and rain down onto the galaxy. 393 00:18:45.599 --> 00:18:49.079 Right, But in the highly dense environments of protoclusters in 394 00:18:49.119 --> 00:18:52.799 the early universe, we see a totally different fluid dynamic. 395 00:18:53.319 --> 00:18:55.880 We see cold streams cold streams. 396 00:18:55.920 --> 00:18:58.240 So the gas in the filaments is so dense that 397 00:18:58.279 --> 00:19:01.079 it doesn't shock heat when it hits the outer boundary 398 00:19:01.119 --> 00:19:03.000 of the dark matter halo exactly. 399 00:19:03.039 --> 00:19:06.000 It maintains its low temperature and essentially punches right through 400 00:19:06.039 --> 00:19:06.519 the hot. 401 00:19:06.359 --> 00:19:10.200