1 00:00:04,270 --> 00:00:07,373 ROWE: Supermassive black holes, 2 00:00:07,474 --> 00:00:10,776 the engines that power our universe. 3 00:00:10,877 --> 00:00:15,447 Supermassive black holes are one of the major players 4 00:00:15,548 --> 00:00:17,483 in the evolution of galaxies. 5 00:00:17,584 --> 00:00:19,485 THALLER: With no supermassive black holes, 6 00:00:19,586 --> 00:00:23,088 you have no Milky Way Galaxy, no sun, no Earth, no you. 7 00:00:25,492 --> 00:00:27,693 ROWE: They're the driving force at the heart 8 00:00:27,794 --> 00:00:30,696 of nearly every galaxy in the cosmos. 9 00:00:30,797 --> 00:00:34,533 They are the most monstrous and scary and bizarre aspects of 10 00:00:34,634 --> 00:00:37,002 our world, which just fascinates me. 11 00:00:37,103 --> 00:00:39,772 ROWE: Now, a new mystery has emerged 12 00:00:39,873 --> 00:00:43,876 about the oldest supermassive black holes. 13 00:00:43,977 --> 00:00:46,011 TREMBLAY: We see supermassive black holes in 14 00:00:46,112 --> 00:00:47,713 the very early universe. 15 00:00:47,814 --> 00:00:51,350 And we don't understand how they grew so large so quickly. 16 00:00:51,451 --> 00:00:54,520 ROWE: We have clues about their formation. 17 00:00:54,621 --> 00:00:56,789 But can we solve the mystery 18 00:00:56,890 --> 00:00:59,258 of this supermassive growth spurt? 19 00:01:01,194 --> 00:01:02,494 [electricity buzzing] 20 00:01:13,573 --> 00:01:15,541 ♪♪ 21 00:01:15,642 --> 00:01:17,709 ROWE: 2017. 22 00:01:17,811 --> 00:01:19,511 Scientists gazing deep into 23 00:01:19,612 --> 00:01:21,914 the distant universe discover something 24 00:01:21,981 --> 00:01:25,184 completely unexpected -- 25 00:01:25,285 --> 00:01:28,520 A vast supermassive black hole dating 26 00:01:28,621 --> 00:01:31,990 from the earliest days of the universe. 27 00:01:32,092 --> 00:01:36,495 MINGARELLI: This was 690 million years after the Big Bang. 28 00:01:36,596 --> 00:01:40,866 The universe was about 5 or 6% of the age that it is now. 29 00:01:42,469 --> 00:01:46,071 Finding a supermassive black hole in the early universe is 30 00:01:46,172 --> 00:01:50,175 like finding an NFL defensive lineman playing 31 00:01:50,276 --> 00:01:51,810 in peewee football. 32 00:01:51,911 --> 00:01:55,180 Something that big shouldn't exist that young. 33 00:01:56,549 --> 00:02:00,752 ROWE: The supermassive black hole wasn't just super early. 34 00:02:00,854 --> 00:02:07,426 It was super big, 800 million times the mass of our sun. 35 00:02:07,527 --> 00:02:09,294 HOPKINS: In just a few hundred million years, 36 00:02:09,395 --> 00:02:12,064 the universe has somehow been able to collapse nearly 37 00:02:12,165 --> 00:02:13,632 a billion suns' worth of 38 00:02:13,733 --> 00:02:15,834 material into a giant black hole. 39 00:02:15,935 --> 00:02:19,371 And we honestly just don't know how that's possible. 40 00:02:19,472 --> 00:02:22,841 ROWE: We measure black holes by the mass of our sun -- 41 00:02:22,942 --> 00:02:23,842 Solar masses. 42 00:02:23,943 --> 00:02:27,746 Regular, or stellar, black holes are a few 43 00:02:27,847 --> 00:02:30,382 to a hundred solar masses. 44 00:02:30,483 --> 00:02:35,320 Supermassive black holes weigh from 100,000 to billions 45 00:02:35,421 --> 00:02:36,655 of suns. 46 00:02:36,756 --> 00:02:41,493 And scientists have now found over 100 of these monsters in 47 00:02:41,594 --> 00:02:43,428 the early universe. 48 00:02:43,530 --> 00:02:46,965 We were shocked to find even one of them existing so early 49 00:02:47,066 --> 00:02:48,200 after the Big Bang. 50 00:02:48,301 --> 00:02:51,036 It was kind of freakish, to be honest, 51 00:02:51,137 --> 00:02:53,572 but then to find that there's whole populations 52 00:02:53,673 --> 00:02:55,607 of these things that exist and are well 53 00:02:55,708 --> 00:02:57,776 in place at the earliest times 54 00:02:57,877 --> 00:03:00,646 that we can look at was truly shocking. 55 00:03:00,747 --> 00:03:03,415 ROWE: We believe supermassive black holes might 56 00:03:03,516 --> 00:03:07,920 help explain the evolution and the destiny of the universe. 57 00:03:08,021 --> 00:03:11,857 Astronomers are striving to understand them. 58 00:03:11,958 --> 00:03:13,926 OLUSEYI: Understanding the origin 59 00:03:14,027 --> 00:03:15,994 of supermassive black holes and how 60 00:03:16,095 --> 00:03:19,865 they could form so early in the universe's history is 61 00:03:19,966 --> 00:03:24,536 something that would change all of astronomy and astrophysics. 62 00:03:25,772 --> 00:03:28,340 How do you get something that massive to 63 00:03:28,441 --> 00:03:31,376 form in such a short amount of time? 64 00:03:31,477 --> 00:03:34,580 It's a big question -- To begin to answer it, 65 00:03:34,681 --> 00:03:37,282 we have to start small, by asking 66 00:03:37,383 --> 00:03:40,485 how regular stellar black holes form. 67 00:03:40,587 --> 00:03:43,622 FILIPPENKO: Black holes form through the collapse of stars. 68 00:03:43,723 --> 00:03:46,391 Everyone knows that -- You have a big enough star, 69 00:03:46,492 --> 00:03:48,160 and it'll collapse to form a black hole. 70 00:03:48,261 --> 00:03:52,164 [explosion blasts] 71 00:03:52,265 --> 00:03:55,534 A really massive star dies in a violent supernova explosion, 72 00:03:55,635 --> 00:03:58,604 and if they have sufficient mass, what's left over 73 00:03:58,705 --> 00:04:00,439 collapses into a black hole. 74 00:04:05,311 --> 00:04:07,346 The bigger the star was, 75 00:04:07,447 --> 00:04:09,448 the bigger the black hole is to start with. 76 00:04:10,617 --> 00:04:12,284 ROWE: Were the stars of the early universe 77 00:04:12,385 --> 00:04:16,054 big enough to collapse into supermassive black holes? 78 00:04:16,155 --> 00:04:20,192 The very early universe was much different than 79 00:04:20,293 --> 00:04:22,327 the university you see around us today. 80 00:04:22,428 --> 00:04:26,365 It was filled entirely with hydrogen and helium gas. 81 00:04:27,700 --> 00:04:30,002 ROWE: This gas amassed into giant clouds, 82 00:04:30,103 --> 00:04:32,704 which collapsed under their own gravity. 83 00:04:34,407 --> 00:04:37,476 Nuclear fusion ignited the dense cores, 84 00:04:37,577 --> 00:04:39,411 and the first stars were born. 85 00:04:41,281 --> 00:04:44,149 Now, we think that these earliest clouds of gas probably 86 00:04:44,250 --> 00:04:46,084 made bigger stars than clouds 87 00:04:46,185 --> 00:04:48,920 of gas do in our local or today's universe. 88 00:04:49,022 --> 00:04:53,058 It was possible to get huge, giant stars that we call 89 00:04:53,159 --> 00:04:58,297 Population III stars that were just utterly massive. 90 00:04:58,398 --> 00:05:02,567 ROWE: Population III stars are the oldest category of star. 91 00:05:02,669 --> 00:05:04,436 Like stellar dinosaurs, 92 00:05:04,537 --> 00:05:07,572 they dominated the universe a long time ago. 93 00:05:07,674 --> 00:05:10,075 Now, they're extinct. 94 00:05:10,176 --> 00:05:11,810 HOPKINS: They'd be weird stars. 95 00:05:11,911 --> 00:05:15,013 They would be incredibly bright in the ultraviolet 96 00:05:15,114 --> 00:05:16,782 and have very unique signatures 97 00:05:16,883 --> 00:05:18,717 that are very different from stars today, 98 00:05:18,818 --> 00:05:21,019 but precisely because they're so big and so bright, 99 00:05:21,120 --> 00:05:23,722 they would be very short-lived. 100 00:05:23,823 --> 00:05:26,825 ROWE: These first stars lived fast and died young... 101 00:05:29,696 --> 00:05:31,396 [explosion blasts] 102 00:05:31,497 --> 00:05:36,001 ...exploding in supernovas, leaving behind black holes. 103 00:05:36,102 --> 00:05:39,938 But were they supermassive black holes? 104 00:05:40,039 --> 00:05:43,442 When a star blows up, when it goes supernova, 105 00:05:43,543 --> 00:05:46,278 most of the mass is ejected away. 106 00:05:46,379 --> 00:05:47,846 It just goes flying out, 107 00:05:47,947 --> 00:05:51,049 leaving a dense neutron star or perhaps a black hole. 108 00:05:51,150 --> 00:05:52,951 But it won't have much mass, because 109 00:05:53,052 --> 00:05:55,220 most of that mass was blown away. 110 00:05:56,989 --> 00:06:00,525 Even though Population III stars in the infant universe 111 00:06:00,626 --> 00:06:01,960 were very large, 112 00:06:02,061 --> 00:06:05,397 they weren't big enough to leave a supermassive black hole 113 00:06:05,498 --> 00:06:08,133 behind when they exploded. 114 00:06:08,234 --> 00:06:11,269 Perhaps if we can skip the supernova step, 115 00:06:11,371 --> 00:06:15,207 that might be one pathway to understanding how supermassive 116 00:06:15,308 --> 00:06:16,708 black holes formed. 117 00:06:16,809 --> 00:06:19,878 Could a dying star's entire mass collapse 118 00:06:19,979 --> 00:06:21,913 into a black hole? 119 00:06:22,014 --> 00:06:27,219 A clue may lie in a galaxy nicknamed the Fireworks Galaxy. 120 00:06:27,320 --> 00:06:30,422 The Fireworks Galaxy has that 121 00:06:30,523 --> 00:06:32,224 flashy name, because when you look at it, 122 00:06:32,325 --> 00:06:36,128 there are all these supernova explosions going off 123 00:06:36,229 --> 00:06:38,430 and, um, making quite a show. 124 00:06:42,402 --> 00:06:44,903 ROWE: Recently, astronomers were keeping an eye on 125 00:06:45,004 --> 00:06:48,807 one extremely bright star in the Fireworks Galaxy. 126 00:06:49,876 --> 00:06:51,843 PLAIT: This star is exactly the kind 127 00:06:51,944 --> 00:06:55,080 that we know explodes as a supernova. 128 00:06:55,181 --> 00:06:57,682 Astronomers expected it to explode, 129 00:06:57,784 --> 00:07:00,519 but then it did something even weirder. 130 00:07:00,620 --> 00:07:03,522 Astronomy is so wonderful, because sometimes you see things 131 00:07:03,623 --> 00:07:05,991 right in front of your eyes that you can't explain. 132 00:07:06,092 --> 00:07:09,961 We saw an entire star just disappear. 133 00:07:10,062 --> 00:07:13,365 ROWE: In 2007, the star looked like this. 134 00:07:13,466 --> 00:07:17,436 By 2015, it had completely vanished. 135 00:07:17,537 --> 00:07:20,005 There was no flare 136 00:07:20,106 --> 00:07:23,608 or debris from a supernova explosion. 137 00:07:23,709 --> 00:07:25,544 So what the heck is going on? 138 00:07:26,913 --> 00:07:30,382 PLAIT: It turns out that not every massive star blows up 139 00:07:30,483 --> 00:07:32,918 with all the fireworks of a normal supernova. 140 00:07:33,019 --> 00:07:36,121 You can get what's called a failed supernova. 141 00:07:36,222 --> 00:07:38,824 ROWE: A supernova fails when the shockwave 142 00:07:38,925 --> 00:07:43,128 generated inside a collapsing star can't escape. 143 00:07:43,229 --> 00:07:45,397 THALLER: In some cases, when the star is very massive, 144 00:07:45,498 --> 00:07:47,666 the shockwave never has a chance to get all the way out of 145 00:07:47,767 --> 00:07:49,634 the star by the time the star itself 146 00:07:49,735 --> 00:07:51,703 collapses into a black hole, 147 00:07:51,804 --> 00:07:54,773 then you have a failed supernova. 148 00:07:54,874 --> 00:07:59,244 ROWE: The Fireworks Galaxy star may have been massive enough to 149 00:07:59,312 --> 00:08:02,380 smother its own explosion before collapsing 150 00:08:02,482 --> 00:08:03,982 to form a black hole. 151 00:08:05,451 --> 00:08:07,352 THALLER: Everything collapses into the black hole. 152 00:08:07,453 --> 00:08:08,887 You can actually have a black hole 153 00:08:08,988 --> 00:08:12,057 with all the mass of the original star. 154 00:08:12,158 --> 00:08:13,458 ROWE: Back in the early universe, 155 00:08:13,559 --> 00:08:16,995 could the enormous Population III stars have died 156 00:08:17,096 --> 00:08:19,164 as failed supernovas, 157 00:08:19,265 --> 00:08:23,235 leaving behind supermassive black holes? 158 00:08:23,336 --> 00:08:27,339 These Population III stars don't seem to me to be 159 00:08:27,440 --> 00:08:30,775 a good contender for the precursor to supermassive 160 00:08:30,877 --> 00:08:33,845 black holes -- they just would not have enough mass. 161 00:08:33,946 --> 00:08:35,881 FILIPPENKO: Even the most massive stars are only 162 00:08:35,982 --> 00:08:39,217 a couple of hundred times more massive than our sun, 163 00:08:39,318 --> 00:08:42,721 whereas a supermassive black hole is millions or billions of 164 00:08:42,822 --> 00:08:44,789 times the mass of our sun. 165 00:08:44,891 --> 00:08:47,359 ROWE: Early supermassive black holes 166 00:08:47,460 --> 00:08:50,128 can't have formed from collapsing stars. 167 00:08:50,229 --> 00:08:53,331 Even giant stars aren't massive enough. 168 00:08:53,432 --> 00:08:56,835 So is there some other path to being supermassive? 169 00:08:56,936 --> 00:08:58,803 Were stellar black holes 170 00:08:58,905 --> 00:09:03,475 cosmic bodybuilders on a fast-track bulking program? 171 00:09:14,153 --> 00:09:16,121 ROWE: How did supermassive black holes in 172 00:09:16,222 --> 00:09:20,358 the early universe get so large so quickly? 173 00:09:20,459 --> 00:09:22,594 We ruled out the idea that they were 174 00:09:22,695 --> 00:09:25,964 created from the collapse of very large stars. 175 00:09:26,065 --> 00:09:28,166 Maybe they started out as smaller, 176 00:09:28,267 --> 00:09:33,305 stellar mass black holes and grew to be supermassive 177 00:09:33,406 --> 00:09:35,106 by eating. 178 00:09:35,207 --> 00:09:36,942 TREMBLAY: Black holes are not fussy eaters. 179 00:09:37,043 --> 00:09:39,311 They'll consume anything that comes in their path. 180 00:09:39,412 --> 00:09:41,913 You know, gas, planets, stars. 181 00:09:42,014 --> 00:09:44,015 It doesn't matter, and everything that they 182 00:09:44,116 --> 00:09:46,318 consume adds mass to the black hole. 183 00:09:47,620 --> 00:09:51,156 ROWE: We've spotted a stellar mass black hole 184 00:09:51,257 --> 00:09:53,992 currently eating in our Milky Way Galaxy. 185 00:09:54,093 --> 00:09:56,761 15 times the mass of the sun, 186 00:09:56,862 --> 00:09:59,898 Cygnus X-1 is steadily feeding 187 00:09:59,999 --> 00:10:03,168 off the material that swirls around it. 188 00:10:03,269 --> 00:10:06,171 MINGARELLI: Some black holes are fed through things called 189 00:10:06,272 --> 00:10:07,439 accretion disks. 190 00:10:07,540 --> 00:10:10,675 It's kind of like the rings around Saturn. 191 00:10:10,743 --> 00:10:13,445 There's this thick or thin disk of 192 00:10:13,546 --> 00:10:15,914 material around the black hole that feeds it. 193 00:10:17,383 --> 00:10:19,851 ROWE: Cygnus X-1's secretion disc gets 194 00:10:19,952 --> 00:10:23,088 constant refills from a nearby source, 195 00:10:23,189 --> 00:10:25,824 a vast star 20 times the mass 196 00:10:25,925 --> 00:10:28,593 of the sun called a blue supergiant. 197 00:10:30,496 --> 00:10:32,664 The black hole has been feeding on gas 198 00:10:32,765 --> 00:10:35,533 from this star for about five million years. 199 00:10:35,635 --> 00:10:39,638 TREMBLAY: So if you ask, how do black holes eat or consume gas? 200 00:10:39,739 --> 00:10:41,206 The answer is gravity, these are 201 00:10:41,307 --> 00:10:44,175 very massive objects, and anything that comes within 202 00:10:44,276 --> 00:10:47,479 their sphere of influence can be consumed by the black hole. 203 00:10:48,848 --> 00:10:51,349 ROWE: The more mass a black hole gains, the greater 204 00:10:51,450 --> 00:10:54,786 its gravity and the more food it attracts. 205 00:10:54,887 --> 00:10:57,856 PLAIT: A black hole growing is a little bit 206 00:10:57,957 --> 00:10:59,724 like a snowball rolling down a hill. 207 00:10:59,825 --> 00:11:02,394 The bigger the snowball gets, the more snow it 208 00:11:02,495 --> 00:11:04,496 can accumulate, and so the bigger it gets. 209 00:11:04,597 --> 00:11:06,297 It's a runaway effect. 210 00:11:06,399 --> 00:11:09,634 ROWE: But even if Cygnus X-1 follows this runaway 211 00:11:09,735 --> 00:11:11,036 growth trajectory, 212 00:11:11,137 --> 00:11:15,306 it still may never reach supermassive status. 213 00:11:16,776 --> 00:11:19,077 The black holes of the early universe must 214 00:11:19,178 --> 00:11:21,246 have fed at a much faster rate. 215 00:11:22,515 --> 00:11:25,583 The biggest issue is how do you have 216 00:11:25,685 --> 00:11:29,287 enough time in the early universe to go 217 00:11:29,388 --> 00:11:34,125 from a small black hole that's born from a star to 218 00:11:34,226 --> 00:11:36,494 something that's supermassive? 219 00:11:39,098 --> 00:11:43,835 ROWE: GRS 1915 is another stellar mass black hole. 220 00:11:43,936 --> 00:11:47,372 It's a greedy eater, accreting at up to 221 00:11:47,473 --> 00:11:50,542 40 times the rate of Cygnus X-1, 222 00:11:50,643 --> 00:11:53,845 and when something gobbles food that quickly, 223 00:11:53,946 --> 00:11:56,548 it can begin to overheat. 224 00:11:56,649 --> 00:11:59,651 MINGARELLI: The black hole is accreting a lot of material, 225 00:11:59,752 --> 00:12:00,919 and as it's eating, 226 00:12:01,020 --> 00:12:03,188 the accretion disc really heats up to very 227 00:12:03,289 --> 00:12:04,422 high temperatures. 228 00:12:04,523 --> 00:12:06,991 And at those high temperatures, you can get 229 00:12:07,093 --> 00:12:09,561 a lot of light coming out of the system. 230 00:12:09,662 --> 00:12:14,132 So the more material that a black hole eats and swallows, 231 00:12:14,233 --> 00:12:15,967 the brighter it shines. 232 00:12:16,068 --> 00:12:19,437 ROWE: This stellar black hole sometimes eats so much 233 00:12:19,538 --> 00:12:21,773 so quickly, its accretion disk 234 00:12:21,874 --> 00:12:25,376 pushes out radiation almost a million times brighter 235 00:12:25,478 --> 00:12:27,812 than our sun, 236 00:12:27,913 --> 00:12:31,516 but this brightness has a serious consequence. 237 00:12:31,617 --> 00:12:35,587 It stops the black hole from eating and growing larger. 238 00:12:35,688 --> 00:12:39,257 If you wanted me to gain as much mass as possible as 239 00:12:39,358 --> 00:12:40,959 quickly as possible, you would just keep 240 00:12:41,060 --> 00:12:45,497 feeding me hamburgers nonstop or whatever, but... 241 00:12:45,598 --> 00:12:49,701 black holes have a problem that when they eat a lot, 242 00:12:49,802 --> 00:12:52,003 they tend to just gobble up a lot of the food in 243 00:12:52,104 --> 00:12:53,304 the neighborhood, and then also, 244 00:12:53,405 --> 00:12:55,039 they start shining out so much stuff 245 00:12:55,141 --> 00:12:58,243 that it pushes away much of the food. 246 00:12:58,344 --> 00:13:00,779 ROWE: The brightness, or luminosity, 247 00:13:00,880 --> 00:13:03,348 gets so intense, it pushes away 248 00:13:03,449 --> 00:13:04,482 incoming material, 249 00:13:04,583 --> 00:13:08,219 a sort of safety valve called the Eddington Limit. 250 00:13:08,320 --> 00:13:11,055 So in many ways, the Eddington rate could be 251 00:13:11,157 --> 00:13:13,892 a kind of a speed limit for the growth of black holes. 252 00:13:13,993 --> 00:13:16,795 It could be a governor that prevents black holes from 253 00:13:16,896 --> 00:13:18,229 growing even faster 254 00:13:18,330 --> 00:13:20,632 by just dumping more and more gas onto it. 255 00:13:20,733 --> 00:13:23,434 Eventually, you're gonna hit that Eddington limit, 256 00:13:23,536 --> 00:13:25,003 and that more gas 257 00:13:25,104 --> 00:13:27,705 that you're dumping on won't actually reach the black hole. 258 00:13:28,974 --> 00:13:31,176 ROWE: This cosmic method of portion control 259 00:13:31,277 --> 00:13:33,044 means that stellar black holes in 260 00:13:33,145 --> 00:13:37,081 the early universe couldn't have gained weight fast enough 261 00:13:37,183 --> 00:13:40,485 to become supermassive. 262 00:13:40,586 --> 00:13:42,787 SUTTER: Black holes need time to grow. 263 00:13:42,888 --> 00:13:44,789 They need to feed. They need to eat. 264 00:13:44,890 --> 00:13:47,025 Maybe you need to skip a few steps. 265 00:13:47,126 --> 00:13:51,396 Maybe you need to start at a medium size or bigger 266 00:13:51,497 --> 00:13:55,066 in order to get to supermassive by the time we observe it. 267 00:13:56,435 --> 00:13:58,803 ROWE: So was there another type of black hole 268 00:13:58,904 --> 00:14:00,104 in the early universe? 269 00:14:00,206 --> 00:14:03,575 Something big enough to grow supermassive 270 00:14:03,676 --> 00:14:04,776 in the time available? 271 00:14:09,415 --> 00:14:12,283 ROWE: In 2017, astronomers studied 272 00:14:12,384 --> 00:14:14,485 a dense star cluster called 273 00:14:14,587 --> 00:14:19,023 47 Tucanae on the outskirts of our own galaxy. 274 00:14:20,559 --> 00:14:23,228 They detected 25 pulsars, 275 00:14:23,329 --> 00:14:25,930 bodies that spin and emit radiation 276 00:14:26,031 --> 00:14:27,732 like cosmic lighthouses. 277 00:14:29,068 --> 00:14:33,805 SUTTER: These pulsars are all orbiting a central object. 278 00:14:33,906 --> 00:14:36,507 And even though we couldn't see the central object itself, 279 00:14:36,609 --> 00:14:41,012 we could watch the behavior in the orbits of all these pulsars 280 00:14:41,080 --> 00:14:43,281 around it, and we could figure out 281 00:14:43,382 --> 00:14:46,017 how big that central object was. 282 00:14:46,118 --> 00:14:47,452 Well, when you do the math, 283 00:14:47,553 --> 00:14:51,189 you come up with something that is about 1,500 to 2,000 284 00:14:51,290 --> 00:14:53,524 times the mass of the sun that's actually hidden in 285 00:14:53,626 --> 00:14:55,059 the heart of that globular cluster. 286 00:14:55,160 --> 00:14:58,029 ROWE: So what is the invisible object? 287 00:14:58,130 --> 00:15:03,167 Whatever's lurking at the center of 47 Tucanae has 288 00:15:03,269 --> 00:15:06,704 to be big, and it has to be black. 289 00:15:06,805 --> 00:15:09,807 ROWE: Astronomers think it's a large black hole. 290 00:15:09,909 --> 00:15:12,110 At 1,500 times 291 00:15:12,211 --> 00:15:14,279 the mass of the sun, the object 292 00:15:14,380 --> 00:15:17,715 is much bigger than a regular stellar black hole, 293 00:15:17,816 --> 00:15:21,152 but too small to be supermassive. 294 00:15:21,253 --> 00:15:25,623 Could it be what's known as an intermediate mass black hole? 295 00:15:25,724 --> 00:15:28,893 It's extremely hard to find any 296 00:15:28,994 --> 00:15:32,196 of these intermediate mass black holes. 297 00:15:32,298 --> 00:15:34,666 ROWE: This rare category of black hole 298 00:15:34,767 --> 00:15:38,870 ranges between 100 and 100,000 solar masses. 299 00:15:38,971 --> 00:15:41,205 At that size, they may have 300 00:15:41,307 --> 00:15:45,143 been large enough to become supermassive very quickly. 301 00:15:45,244 --> 00:15:48,947 Intermediate mass black holes could be what give 302 00:15:49,048 --> 00:15:52,684 supermassive black holes a head start in life. 303 00:15:52,785 --> 00:15:54,819 ROWE: Astronomers have never seen 304 00:15:54,920 --> 00:15:56,955 an intermediate mass black hole, 305 00:15:57,056 --> 00:16:01,192 but now, we've heard one, calling to us 306 00:16:01,293 --> 00:16:02,860 from across the universe. 307 00:16:15,607 --> 00:16:19,610 ROWE: Astronomers search for intermediate mass black holes. 308 00:16:19,712 --> 00:16:21,112 They may have been large enough 309 00:16:21,213 --> 00:16:24,115 to act as seeds for the first supermassive 310 00:16:24,216 --> 00:16:25,817 black holes. 311 00:16:25,918 --> 00:16:28,820 Yet so far, they've escaped discovery. 312 00:16:28,921 --> 00:16:30,855 They're like the missing link. And I 313 00:16:30,956 --> 00:16:33,024 mean that for real. They're missing. 314 00:16:33,125 --> 00:16:36,127 Imagine you're an alien who's arrived on the planet Earth, 315 00:16:36,228 --> 00:16:39,097 and you know very little about the human species, 316 00:16:39,198 --> 00:16:42,033 and when you look around, you only notice tiny, 317 00:16:42,134 --> 00:16:44,402 tiny little children and grown adults. 318 00:16:44,503 --> 00:16:47,171 You don't see any adolescents, right? 319 00:16:47,272 --> 00:16:49,807 And intrinsically, you know that the tiny little 320 00:16:49,908 --> 00:16:53,044 children grow up to be full-size adults. 321 00:16:53,145 --> 00:16:55,813 But you don't see how they got there, right? 322 00:16:55,914 --> 00:16:58,182 You don't see the intermediate stages of growth. 323 00:16:58,283 --> 00:17:00,451 That would be really, really weird, right? 324 00:17:00,552 --> 00:17:03,221 That is the case for supermassive black holes. 325 00:17:03,322 --> 00:17:06,457 So it's like a universe without teenagers. 326 00:17:06,558 --> 00:17:10,094 ROWE: Or that's how it looked, until September 2020. 327 00:17:10,195 --> 00:17:13,531 Scientists studying gravitational waves 328 00:17:13,632 --> 00:17:16,434 picked up the signal of an extreme event 329 00:17:16,502 --> 00:17:18,403 in the distant universe. 330 00:17:18,504 --> 00:17:20,571 What researchers are looking for 331 00:17:20,672 --> 00:17:22,807 are things called gravitational waves. 332 00:17:22,908 --> 00:17:25,710 They're like ripples in space itself. 333 00:17:25,811 --> 00:17:29,213 Most signals sound a little bit like a chirp. 334 00:17:29,314 --> 00:17:31,816 It's a noise that's very characteristic. 335 00:17:31,917 --> 00:17:33,418 It goes a bit, like, sort of whoop! 336 00:17:33,519 --> 00:17:35,620 [whooping noise] 337 00:17:35,721 --> 00:17:38,689 But this particular event was so extreme 338 00:17:38,791 --> 00:17:41,459 and so sudden, it just sounded more like a thud. 339 00:17:41,560 --> 00:17:43,494 [faint thud] 340 00:17:43,595 --> 00:17:46,597 ROWE: This faint thud from halfway across the universe 341 00:17:46,698 --> 00:17:51,002 is music to the ears of intermediate black hole hunters, 342 00:17:51,103 --> 00:17:53,971 because its pitch can mean only one thing. 343 00:17:54,073 --> 00:17:57,875 This could only have been created by two 344 00:17:57,976 --> 00:18:02,246 really massive black holes colliding into each other 345 00:18:02,347 --> 00:18:04,982 and producing a combined black hole with 346 00:18:05,084 --> 00:18:10,955 a mass that's 142 times the mass of our sun. 347 00:18:11,056 --> 00:18:13,624 So that, is for the first time, 348 00:18:13,759 --> 00:18:17,628 getting into this intermediate mass black hole regime. 349 00:18:17,729 --> 00:18:20,198 ROWE: This is the first confirmed 350 00:18:20,299 --> 00:18:23,468 observation of an intermediate black hole. 351 00:18:23,569 --> 00:18:26,037 Finding direct evidence like this for 352 00:18:26,105 --> 00:18:30,041 an intermediate mass black hole is absolutely fantastic. 353 00:18:31,410 --> 00:18:34,479 ROWE: Now that we're certain intermediate black holes exist, 354 00:18:34,580 --> 00:18:37,348 could they help explain the origin of supermassive 355 00:18:37,449 --> 00:18:39,183 black holes in the early universe? 356 00:18:39,284 --> 00:18:43,621 These intermediate black holes really could be 357 00:18:43,722 --> 00:18:46,591 the first seeds of the supermassive black holes. 358 00:18:46,692 --> 00:18:50,394 You would need something like that to form really big, 359 00:18:50,496 --> 00:18:54,031 really early to even begin to explain these very massive, 360 00:18:54,133 --> 00:18:56,367 supermassive black holes that have formed 361 00:18:56,468 --> 00:18:59,170 just a short time after the Big Bang. 362 00:18:59,271 --> 00:19:04,142 ROWE: How do intermediate black holes form in the first place? 363 00:19:04,243 --> 00:19:06,544 The recently discovered one came from 364 00:19:06,645 --> 00:19:09,347 the collision of two smaller black holes. 365 00:19:09,448 --> 00:19:13,317 They may also form in giant clouds of gas. 366 00:19:13,418 --> 00:19:17,088 It could be that in the earlier universe, 367 00:19:17,189 --> 00:19:21,192 you can just have large clouds of gas that can lose 368 00:19:21,293 --> 00:19:23,427 enough energy quickly enough to 369 00:19:23,529 --> 00:19:28,666 just spontaneously collapse and form a black hole of this size. 370 00:19:28,767 --> 00:19:32,236 HOPKINS: The enormous cloud of gas contracts and gets denser 371 00:19:32,337 --> 00:19:35,840 and denser, the way it would if it was starting to form stars. 372 00:19:35,941 --> 00:19:38,376 But it's somehow able to remain coherent 373 00:19:38,477 --> 00:19:40,811 and collapse into one giant object 374 00:19:40,913 --> 00:19:43,147 that forms an intermediate mass black hole. 375 00:19:44,616 --> 00:19:48,219 ROWE: A giant gas cloud undergoing a direct collapse 376 00:19:48,320 --> 00:19:50,922 down to an intermediate mass black hole 377 00:19:51,023 --> 00:19:52,557 would be a rare sight. 378 00:19:55,994 --> 00:19:59,597 You think it would go giant cloud, slowly collapsing, 379 00:19:59,698 --> 00:20:01,465 black hole, but instead, 380 00:20:01,567 --> 00:20:05,102 it's more like, giant cloud, ahhhh!!!! Black hole. 381 00:20:06,171 --> 00:20:11,409 So one day, you see this massive gas complex, and then 382 00:20:11,510 --> 00:20:13,611 you blink, and it's collapsed, 383 00:20:13,712 --> 00:20:17,181 and now you're face-to-face with a big black hole. 384 00:20:17,282 --> 00:20:18,916 ROWE: At least, that's the theory. 385 00:20:20,485 --> 00:20:22,687 Getting a black hole to form from 386 00:20:22,788 --> 00:20:26,691 the direct collapse of a gas cloud is very tricky. 387 00:20:26,792 --> 00:20:30,161 ROWE: Gas clouds tend to split up and collapse 388 00:20:30,262 --> 00:20:33,464 into a multitude of stars -- Collapsing into 389 00:20:33,565 --> 00:20:36,667 one object would take unique conditions. 390 00:20:37,936 --> 00:20:42,640 One possible scenario involves two neighboring galaxies. 391 00:20:42,741 --> 00:20:45,843 The first, a young protogalaxy, 392 00:20:45,944 --> 00:20:49,247 a gas cloud yet to form stars. 393 00:20:49,314 --> 00:20:53,417 Next door sits a larger galaxy. 394 00:20:53,552 --> 00:20:55,753 It's forming so many stars, 395 00:20:55,854 --> 00:20:58,990 radiation is bursting out all over its young neighbor. 396 00:21:00,058 --> 00:21:02,026 Because they're in close proximity, 397 00:21:02,127 --> 00:21:04,528 the energy from the large galaxy 398 00:21:04,630 --> 00:21:08,132 prevents the smaller galaxy from forming its stars, 399 00:21:08,233 --> 00:21:10,201 so that means that it will continue 400 00:21:10,302 --> 00:21:13,871 to collapse in cloud form before moving to 401 00:21:13,972 --> 00:21:15,873 star formation. 402 00:21:15,974 --> 00:21:18,509 ROWE: The gas cloud becomes large and dense enough, 403 00:21:18,610 --> 00:21:21,512 the gravity eventually pulls it in on itself. 404 00:21:22,881 --> 00:21:24,682 When it can't ignite into stars, 405 00:21:24,783 --> 00:21:28,019 the collapse creates an intermediate mass black hole. 406 00:21:30,088 --> 00:21:32,790 SUTTER: I think this idea is very intriguing. 407 00:21:32,891 --> 00:21:35,559 I don't know if it's physically possible, 408 00:21:35,661 --> 00:21:36,761 but then again, 409 00:21:36,862 --> 00:21:39,063 there's a lot we don't know about the early universe. 410 00:21:39,164 --> 00:21:44,068 ROWE: Whichever way intermediate mass black holes form, 411 00:21:44,169 --> 00:21:47,571 they seem like a good way to start explaining supermassive 412 00:21:47,673 --> 00:21:50,741 black holes in the early universe. 413 00:21:50,842 --> 00:21:52,910 The question is, then, how do they grow? 414 00:21:53,011 --> 00:21:55,680 How do you start from this seed and end up, 415 00:21:55,781 --> 00:21:57,915 you know, with something that's a billion times the mass of 416 00:21:58,016 --> 00:21:59,250 the sun? 417 00:21:59,351 --> 00:22:03,020 ROWE: Maybe early intermediate mass black holes had 418 00:22:03,121 --> 00:22:04,555 enormous appetites, 419 00:22:04,656 --> 00:22:09,460 gorging themselves to a supermassive state, feeding on 420 00:22:09,561 --> 00:22:13,431 the biggest meals our universe can serve up. 421 00:22:13,532 --> 00:22:18,336 ♪♪ 422 00:22:26,278 --> 00:22:28,746 ROWE: Astronomers want to know how the earliest 423 00:22:28,847 --> 00:22:32,316 supermassive black holes got so big so quickly. 424 00:22:35,487 --> 00:22:37,555 Could they have started as intermediate 425 00:22:37,656 --> 00:22:41,492 mass black holes that devoured supersized meals? 426 00:22:42,861 --> 00:22:45,930 It's possible that these intermediate mass black holes 427 00:22:46,031 --> 00:22:49,266 could form in an exceptionally rare environment where it can 428 00:22:49,368 --> 00:22:52,670 accrete new material at an enormously high rate. 429 00:22:54,539 --> 00:22:56,207 ROWE: So far, we only have direct 430 00:22:56,308 --> 00:23:00,144 evidence of one intermediate mass black hole, 431 00:23:00,245 --> 00:23:04,415 and we can't yet detect how it eats and grows. 432 00:23:04,516 --> 00:23:08,352 But we could look at much larger black holes for clues. 433 00:23:09,688 --> 00:23:13,391 In 2019, astronomers searched for supermassive 434 00:23:13,492 --> 00:23:16,594 black holes that are actively feeding. 435 00:23:16,695 --> 00:23:18,763 They pinpointed 12 quasars 436 00:23:18,864 --> 00:23:21,432 from the beginning of the cosmos. 437 00:23:21,533 --> 00:23:23,467 HOPKINS: Quasars are among the brightest objects 438 00:23:23,568 --> 00:23:24,902 we know of in the universe. 439 00:23:25,003 --> 00:23:28,339 And they're what happens when a supermassive black hole at 440 00:23:28,440 --> 00:23:30,741 the center of a galaxy is swallowing 441 00:23:30,842 --> 00:23:34,078 up gas and dust, and that generates a tremendous amount 442 00:23:34,179 --> 00:23:37,181 of energy and luminosity that we can see. 443 00:23:37,282 --> 00:23:39,483 ROWE: Surrounding these early galaxies are 444 00:23:39,584 --> 00:23:43,254 enormous gas reservoirs called hydrogen halos. 445 00:23:43,355 --> 00:23:45,189 PLAIT: This is great, because that acts 446 00:23:45,290 --> 00:23:48,292 as fuel for those supermassive black holes. 447 00:23:48,393 --> 00:23:51,729 Cold gas can stream into those black holes and feed them. 448 00:23:51,830 --> 00:23:54,432 ROWE: These huge halos of cold gas 449 00:23:54,533 --> 00:23:58,335 are also the building blocks of stars. 450 00:23:58,437 --> 00:24:00,638 TREMBLAY: These enormous, pristine halos 451 00:24:00,739 --> 00:24:02,940 of hydrogen around early galaxies, 452 00:24:03,041 --> 00:24:08,112 they're gonna be reservoirs to power star formation. 453 00:24:08,213 --> 00:24:10,948 ROWE: Star formation is a violent process 454 00:24:11,049 --> 00:24:13,584 that can create turbulence in a galaxy. 455 00:24:13,685 --> 00:24:17,822 That turbulence makes the gas fall toward the black hole, 456 00:24:17,923 --> 00:24:21,325 and then that makes the black hole even bigger. 457 00:24:21,426 --> 00:24:24,595 ROWE: Hydrogen halos might have spoon fed 458 00:24:24,696 --> 00:24:26,697 early supermassive black holes. 459 00:24:26,798 --> 00:24:29,967 This process may have also helped 460 00:24:30,068 --> 00:24:33,370 intermediate mass black holes grow quickly. 461 00:24:33,472 --> 00:24:37,074 Could the largest black holes show us 462 00:24:37,175 --> 00:24:39,777 other, more drastic ways to put on weight? 463 00:24:43,181 --> 00:24:47,117 In October 2019, astronomers used telescopes to 464 00:24:47,219 --> 00:24:52,456 explore a remarkably clear galaxy called M77. 465 00:24:52,557 --> 00:24:55,326 Because this galaxy is so near to us, 466 00:24:55,427 --> 00:24:59,196 we can study its central engine in really exquisite detail at 467 00:24:59,297 --> 00:25:01,632 very, very fine resolution. 468 00:25:01,733 --> 00:25:02,967 SUTTER: Not only do you see 469 00:25:03,068 --> 00:25:04,869 the bright core, the bright nucleus, 470 00:25:04,970 --> 00:25:07,171 but you can see spiral arms. 471 00:25:07,272 --> 00:25:09,507 You can see structures in the galaxy. 472 00:25:09,608 --> 00:25:13,611 You can see how the whole galaxy is arranged. 473 00:25:13,712 --> 00:25:16,146 ROWE: When we examined M77's central 474 00:25:16,248 --> 00:25:20,050 supermassive black hole, we saw something extraordinary. 475 00:25:20,151 --> 00:25:23,087 Its food was coming not from one, 476 00:25:23,188 --> 00:25:26,957 but two accretion disks spinning in 477 00:25:27,058 --> 00:25:28,893 opposite directions. 478 00:25:28,994 --> 00:25:31,428 Normally around a black hole, all of the gas is spinning in 479 00:25:31,530 --> 00:25:32,463 roughly the same direction, 480 00:25:32,564 --> 00:25:34,965 and that creates kind of a slow infall of gas 481 00:25:35,066 --> 00:25:36,734 and slow feeding -- here, 482 00:25:36,835 --> 00:25:38,168 we've got a case where some of it's going 483 00:25:38,270 --> 00:25:41,038 one way, the other is going the other way. 484 00:25:41,139 --> 00:25:44,308 This is very unstable and can create opportunities for lots 485 00:25:44,442 --> 00:25:47,978 of gas to get gobbled up by that black hole. 486 00:25:48,079 --> 00:25:50,214 ROWE: The material in the disks 487 00:25:50,315 --> 00:25:54,385 is one enormous ready-to-eat meal, 488 00:25:54,486 --> 00:25:57,521 but dinner will not be served until the outer disk 489 00:25:57,622 --> 00:25:58,789 slows down. 490 00:25:58,890 --> 00:26:01,125 HOPKINS: If there's a black hole at the center of a galaxy, 491 00:26:01,226 --> 00:26:02,927 and you're orbiting around it 492 00:26:03,028 --> 00:26:05,162 fast enough to maintain your orbit, 493 00:26:05,263 --> 00:26:06,897 you're never going to fall in. 494 00:26:06,998 --> 00:26:09,567 You're just going to orbit forever, and you're just going 495 00:26:09,668 --> 00:26:11,001 to spin around, just like the way the Earth 496 00:26:11,102 --> 00:26:12,403 is going around the sun. 497 00:26:12,504 --> 00:26:14,805 What needs to happen if you wanna fall in, 498 00:26:14,906 --> 00:26:17,408 is to slow down your speed. 499 00:26:17,509 --> 00:26:20,411 ROWE: The outer accretion disk will gradually slow down 500 00:26:20,512 --> 00:26:23,213 and orbit more tightly against the inner disk. 501 00:26:23,315 --> 00:26:26,984 Dangerous collisions of the counter-rotating 502 00:26:27,085 --> 00:26:29,620 material will start to occur. 503 00:26:29,721 --> 00:26:32,256 SUTTER: The double accretion disk is like drinking 504 00:26:32,357 --> 00:26:34,825 from two soda fountains at the same time. 505 00:26:34,926 --> 00:26:36,226 It's great while it lasts, 506 00:26:36,328 --> 00:26:39,296 but you're building up some serious gas that is just gonna 507 00:26:39,397 --> 00:26:41,131 blow the whole thing away. 508 00:26:41,232 --> 00:26:43,067 ROWE: In just a few 100,000 years, 509 00:26:43,168 --> 00:26:46,270 the double disks will catastrophically collide, 510 00:26:46,371 --> 00:26:49,006 and their entire contents will fall 511 00:26:49,107 --> 00:26:52,676 into the central supermassive black hole. 512 00:26:52,777 --> 00:26:55,512 It will devour everything in one gulp, 513 00:26:55,614 --> 00:26:58,882 generating a colossal cosmic burp. 514 00:27:06,424 --> 00:27:10,828 In February of 2020, in the Ophiuchus Galaxy Cluster, 515 00:27:10,929 --> 00:27:14,164 we saw the damage a cosmic burp can do. 516 00:27:16,301 --> 00:27:19,236 PLAIT: The Ophiuchus Galaxy Cluster is a collection of 517 00:27:19,337 --> 00:27:22,573 a huge number of galaxies, all bound together by gravity. 518 00:27:22,674 --> 00:27:25,576 And there's gas in between these galaxies. 519 00:27:25,677 --> 00:27:27,745 And when astronomers looked at that gas in detail, 520 00:27:27,846 --> 00:27:31,148 what they found was a huge arcing structure in it that 521 00:27:31,249 --> 00:27:34,018 they realized was the edge of a cavity. 522 00:27:37,322 --> 00:27:40,891 SUTTER: There is a massive hole in the gas that is 523 00:27:40,992 --> 00:27:45,596 over 15 times bigger than the entire Milky Way Galaxy. 524 00:27:45,697 --> 00:27:52,269 Something frightening had to happen to carve this void out. 525 00:27:52,370 --> 00:27:56,740 PLAIT: The size of this bubble is kind of stomping my brain. 526 00:27:56,841 --> 00:27:58,142 We are talking about 527 00:27:58,243 --> 00:28:03,747 a hole in this gas that is over a million light-years wide. 528 00:28:03,848 --> 00:28:05,582 ROWE: The burp that created this cavity 529 00:28:05,684 --> 00:28:08,585 must have been astoundingly powerful. 530 00:28:08,687 --> 00:28:10,821 PLAIT: There are a lot of ideas about this, 531 00:28:10,922 --> 00:28:13,390 but there's only one that really can explain it. 532 00:28:13,491 --> 00:28:15,259 And that's a supermassive black hole. 533 00:28:16,728 --> 00:28:20,764 A supermassive black hole that suddenly got very greedy. 534 00:28:21,833 --> 00:28:25,703 In order to drive an energetic event like this, 535 00:28:25,804 --> 00:28:29,239 the black hole needs to eat -- Not just one meal. 536 00:28:29,340 --> 00:28:34,411 It needs to eat thousands of meals at the exact same time. 537 00:28:34,512 --> 00:28:37,514 It needs to go to an all-you-can-eat 538 00:28:37,615 --> 00:28:39,616 intergalactic buffet. 539 00:28:39,718 --> 00:28:41,652 Sometime in the distant past, 540 00:28:41,753 --> 00:28:46,957 this black hole must have had a huge episode of just gorging 541 00:28:47,058 --> 00:28:50,094 on material falling in -- That got superhot, 542 00:28:50,195 --> 00:28:53,664 blew out a tremendous amount of material in jets, 543 00:28:53,765 --> 00:28:56,767 beams that shot out from the poles of the disk. 544 00:28:56,868 --> 00:29:00,637 And that's what basically pushed its way out of that gas, 545 00:29:00,739 --> 00:29:03,140 forming this enormous cavity. 546 00:29:03,241 --> 00:29:06,810 ROWE: The colossal cosmic burp pushed food far 547 00:29:06,911 --> 00:29:09,813 away from the supermassive black hole, ending 548 00:29:09,914 --> 00:29:13,350 its all-you-can-eat binge and stopping its growth. 549 00:29:14,452 --> 00:29:17,521 If an intermediate mass black hole was this greedy, 550 00:29:17,622 --> 00:29:20,557 it would come to a similar end. 551 00:29:20,658 --> 00:29:24,762 It's no way to gain weight and become supermassive. 552 00:29:24,863 --> 00:29:27,164 This is probably not the way the earliest 553 00:29:27,265 --> 00:29:31,001 supermassive black holes grew to such enormous size. 554 00:29:31,102 --> 00:29:33,737 ROWE: Is there another way supermassive black holes 555 00:29:33,838 --> 00:29:34,972 could have formed 556 00:29:35,073 --> 00:29:37,741 in the early universe without having to overeat? 557 00:29:39,110 --> 00:29:43,514 Maybe black holes smashed their way to being giant-sized. 558 00:29:45,083 --> 00:29:47,885 [explosion blasts] 559 00:30:00,365 --> 00:30:02,866 ROWE: November 2018. 560 00:30:02,967 --> 00:30:04,968 Astronomers scanning hundreds of 561 00:30:05,069 --> 00:30:08,205 nearby galaxies in infrared light spot 562 00:30:08,306 --> 00:30:10,440 something extraordinary. 563 00:30:12,977 --> 00:30:16,547 Some galaxies had not one supermassive black hole, 564 00:30:16,648 --> 00:30:18,215 but two. 565 00:30:20,652 --> 00:30:22,986 Are these pairs a clue to how supermassive 566 00:30:23,087 --> 00:30:27,291 black holes in the infant universe got so big so fast? 567 00:30:28,660 --> 00:30:32,696 Seeing these infrared images showing pairs of supermassive 568 00:30:32,797 --> 00:30:35,532 black holes at the centers of galaxies 569 00:30:35,633 --> 00:30:39,102 and showing that this could be very common 570 00:30:39,204 --> 00:30:41,638 just is mind-blowing to me. 571 00:30:41,739 --> 00:30:45,209 The reason we see pairs of supermassive black holes 572 00:30:45,310 --> 00:30:48,545 is because two galaxies merged together. 573 00:30:48,646 --> 00:30:51,748 MINGARELLI: In our picture of how the universe works, 574 00:30:51,850 --> 00:30:56,687 galaxies start off as smaller galaxies and grow by merging 575 00:30:56,788 --> 00:30:58,155 with other galaxies. 576 00:30:58,256 --> 00:31:00,891 So they'll be whooshing around each other 577 00:31:00,992 --> 00:31:03,093 and tearing each other up. 578 00:31:03,194 --> 00:31:05,095 It's actually quite violent. 579 00:31:05,196 --> 00:31:08,265 ROWE: When galaxies merge, we think their central 580 00:31:08,366 --> 00:31:11,068 supermassive black holes also merge, 581 00:31:11,169 --> 00:31:14,338 smashing into each other and combining to build 582 00:31:14,439 --> 00:31:16,273 a larger black hole. 583 00:31:16,374 --> 00:31:18,575 Galaxy-scale mergers can be one of the most 584 00:31:18,676 --> 00:31:22,112 efficient growth mechanisms for supermassive black holes. 585 00:31:23,548 --> 00:31:25,449 ROWE: Maybe, in the early universe, 586 00:31:25,550 --> 00:31:28,619 black holes of stellar or intermediate mass 587 00:31:28,720 --> 00:31:31,822 merged repeatedly, getting heavier 588 00:31:31,923 --> 00:31:35,792 and heavier until they became super massive. 589 00:31:38,062 --> 00:31:39,730 STRAUGHN: We don't really know how common 590 00:31:39,831 --> 00:31:42,599 supermassive black hole mergers were in the early universe, 591 00:31:42,700 --> 00:31:45,269 but we think they were more common than they are today, 592 00:31:45,370 --> 00:31:48,038 because galaxies were closer together. 593 00:31:48,139 --> 00:31:51,875 ROWE: It would have taken millions of mergers to build up 594 00:31:51,976 --> 00:31:55,746 the largest supermassive black holes we see today, 595 00:31:55,847 --> 00:31:57,981 which could have been a tall order. 596 00:32:03,888 --> 00:32:05,989 There's another problem, too. 597 00:32:06,090 --> 00:32:07,891 We've never witnessed a supermassive 598 00:32:07,992 --> 00:32:09,726 black hole merger in the act. 599 00:32:09,827 --> 00:32:13,030 We've seen supermassive black holes on their way to merging, 600 00:32:13,097 --> 00:32:16,466 and we've seen ones that we think had gone through mergers. 601 00:32:16,567 --> 00:32:19,169 But we haven't caught one in the moment. 602 00:32:19,270 --> 00:32:22,005 ROWE: As supermassive black holes start merging, 603 00:32:22,106 --> 00:32:24,074 they spiral around each other, 604 00:32:24,175 --> 00:32:27,377 getting faster and faster the closer they get. 605 00:32:29,480 --> 00:32:31,648 But for them to finally merge together 606 00:32:31,749 --> 00:32:33,784 into a single black hole, 607 00:32:33,885 --> 00:32:36,553 they need to lose what astronomers call 608 00:32:36,654 --> 00:32:38,655 orbital energy. 609 00:32:38,756 --> 00:32:42,326 The merger of supermassive black holes means that 610 00:32:42,427 --> 00:32:43,927 their orbits have to decay 611 00:32:44,028 --> 00:32:45,929 for them to get closer and closer together. 612 00:32:46,030 --> 00:32:48,231 So in order for an orbit to decay, 613 00:32:48,333 --> 00:32:51,168 that orbital energy has to go somewhere. 614 00:32:51,269 --> 00:32:52,669 ROWE: To lose energy, 615 00:32:52,770 --> 00:32:56,473 the merging supermassive black holes start disrupting 616 00:32:56,574 --> 00:32:58,842 the orbits of nearby stars, 617 00:32:58,943 --> 00:33:01,712 throwing them off their paths. 618 00:33:01,813 --> 00:33:04,181 HOPKINS: So something small and puny that weighs 619 00:33:04,282 --> 00:33:07,918 just one sun like our own star will often get in 620 00:33:08,019 --> 00:33:10,687 the path of these two and just get rocketed out, 621 00:33:10,788 --> 00:33:15,726 potentially unbound and flung out of the galaxy entirely. 622 00:33:15,827 --> 00:33:18,061 ROWE: Each time the supermassive black holes 623 00:33:18,162 --> 00:33:21,965 fling out a star, they lose more orbital energy. 624 00:33:22,066 --> 00:33:24,468 They get closer and closer. 625 00:33:24,569 --> 00:33:26,503 But eventually, they kicked out all the stars. 626 00:33:26,604 --> 00:33:28,338 There's nothing left. 627 00:33:28,439 --> 00:33:30,707 ROWE: The merger stalls. 628 00:33:30,808 --> 00:33:33,076 Like two sweethearts at a high school prom, 629 00:33:34,479 --> 00:33:38,882 the supermassive black holes dance as close as they can, 630 00:33:38,983 --> 00:33:41,585 but physical contact is not allowed. 631 00:33:43,554 --> 00:33:46,023 So these two black holes could end up spiraling 632 00:33:46,124 --> 00:33:49,159 around each other for billions and billions of years. 633 00:33:49,260 --> 00:33:51,194 This is called the final parsec problem. 634 00:33:54,565 --> 00:33:57,834 MINGARELLI: In 1980, there was a famous paper, 635 00:33:57,935 --> 00:34:00,003 which addressed this issue that 636 00:34:00,104 --> 00:34:02,272 supermassive black holes can only get to 637 00:34:02,373 --> 00:34:05,776 within about one parsec, or three light-years, of each other 638 00:34:05,877 --> 00:34:10,614 before they can't merge or they stall. 639 00:34:10,715 --> 00:34:14,017 We believe that supermassive black holes must merge. 640 00:34:14,118 --> 00:34:17,054 We know that galaxies merge, and so if the black holes 641 00:34:17,155 --> 00:34:19,656 didn't merge, we'd see lots of black holes floating around. 642 00:34:19,757 --> 00:34:21,458 And we don't -- there's always one in the middle. 643 00:34:21,559 --> 00:34:23,226 So how do they merge? 644 00:34:24,796 --> 00:34:27,931 ROWE: In 2019, we found something that appears 645 00:34:28,032 --> 00:34:30,967 to solve the final parsec problem -- 646 00:34:31,069 --> 00:34:33,303 A galaxy in the middle of a merger 647 00:34:33,404 --> 00:34:36,573 that contains not two supermassive black holes, 648 00:34:36,641 --> 00:34:38,308 but three. 649 00:34:38,409 --> 00:34:40,710 MINGARELLI: Three supermassive black holes. 650 00:34:40,812 --> 00:34:42,279 Now that's really cool. 651 00:34:42,380 --> 00:34:44,848 Sometimes you can have three galaxies 652 00:34:44,949 --> 00:34:48,085 that are merging together in a galaxy cluster. 653 00:34:48,186 --> 00:34:50,387 Then you have three supermassive black holes. 654 00:34:50,488 --> 00:34:51,621 At this point is, 655 00:34:51,722 --> 00:34:53,457 it's virtually impossible for there to be 656 00:34:53,558 --> 00:34:55,692 a final parsec problem. 657 00:34:55,793 --> 00:34:58,829 ROWE: Here's how a third black hole solves the final 658 00:34:58,930 --> 00:35:00,864 parsec problem. 659 00:35:00,965 --> 00:35:04,201 Two of the black holes orbit closer and closer, 660 00:35:04,302 --> 00:35:07,304 ejecting stars to lose energy. 661 00:35:07,405 --> 00:35:10,607 Black hole number three joins the action. 662 00:35:10,708 --> 00:35:13,243 Its gravitational pull takes even 663 00:35:13,311 --> 00:35:15,846 more energy from the orbiting pair. 664 00:35:15,947 --> 00:35:21,785 Eventually, they lose enough orbital energy to collide. 665 00:35:21,886 --> 00:35:25,689 OLUSEYI: That third supermassive black hole is just what's needed 666 00:35:25,756 --> 00:35:27,757 to transfer energy away from 667 00:35:27,859 --> 00:35:31,428 the two merging black holes so that they can now merge into 668 00:35:31,529 --> 00:35:34,397 one single supermassive black hole. 669 00:35:34,499 --> 00:35:37,534 ROWE: Triple black hole events may explain how 670 00:35:37,635 --> 00:35:40,737 the earliest supermassive black holes grew 671 00:35:40,838 --> 00:35:42,305 to such enormous size. 672 00:35:42,406 --> 00:35:47,544 We've suspected that three black holes 673 00:35:47,645 --> 00:35:51,848 may be necessary in order to get black holes to merge, 674 00:35:51,949 --> 00:35:54,084 but we've never had any evidence for it. 675 00:35:54,185 --> 00:35:57,587 But now, this might provide a direct picture 676 00:35:57,688 --> 00:36:02,325 of three black holes caught in the act itself. 677 00:36:02,426 --> 00:36:05,595 If we have a picture of this happening now, 678 00:36:05,696 --> 00:36:09,866 then it certainly happened in the early universe and might 679 00:36:09,967 --> 00:36:14,204 explain how the biggest black holes got so big so quickly. 680 00:36:15,706 --> 00:36:18,275 ROWE: Final proof will come when we witness a merger 681 00:36:18,376 --> 00:36:19,342 being completed. 682 00:36:20,678 --> 00:36:25,382 Scientists are also investigating invisible forces 683 00:36:25,483 --> 00:36:26,983 at the beginning of the universe. 684 00:36:27,051 --> 00:36:29,886 Did something we can't see boost 685 00:36:29,987 --> 00:36:33,023 the size of the first supermassive black holes? 686 00:36:43,968 --> 00:36:47,470 ROWE: One of the greatest mysteries in cosmology is how 687 00:36:47,572 --> 00:36:53,043 the first supermassive black holes got so large so quickly. 688 00:36:53,144 --> 00:36:56,780 We suspect mergers could help explain their size, 689 00:36:56,881 --> 00:36:59,382 and we know all types of black holes 690 00:36:59,483 --> 00:37:01,618 can grow by feeding, 691 00:37:01,719 --> 00:37:03,687 but we need more clues. 692 00:37:03,788 --> 00:37:07,924 There's still so much we don't know about the early universe. 693 00:37:08,025 --> 00:37:10,293 SUTTER: The further out we look in the universe, 694 00:37:10,394 --> 00:37:13,129 the less familiar the universe becomes. 695 00:37:13,231 --> 00:37:19,436 And so the more and more interesting and new physics 696 00:37:19,537 --> 00:37:22,672 you need to involve in order to explain these very 697 00:37:22,773 --> 00:37:25,208 strange observations. 698 00:37:25,309 --> 00:37:27,043 ROWE: The puzzle of fast-growing, 699 00:37:27,144 --> 00:37:30,880 supermassive black holes in the infant universe now takes 700 00:37:30,982 --> 00:37:34,484 physicists somewhere new, to the little 701 00:37:34,585 --> 00:37:37,387 understood realm of magnetic fields. 702 00:37:38,789 --> 00:37:41,157 The thing about magnetic fields is they're hard. 703 00:37:41,259 --> 00:37:43,360 They're hard to calculate, they're hard to understand. 704 00:37:43,461 --> 00:37:45,862 They're sort of the elephant in the room for astronomers. 705 00:37:45,963 --> 00:37:47,364 We know they're there, but we'd 706 00:37:47,465 --> 00:37:49,532 really rather not talk about them. 707 00:37:49,634 --> 00:37:52,402 It's only recently that people are incorporating 708 00:37:52,503 --> 00:37:55,972 magnetic fields into their models of galaxy formation, 709 00:37:56,073 --> 00:38:00,010 and therefore, maybe it's under the influence of these fields 710 00:38:00,111 --> 00:38:02,846 that somehow these supermassive black holes are formed. 711 00:38:04,315 --> 00:38:07,017 ROWE: To investigate how magnetic fields influenced 712 00:38:07,118 --> 00:38:09,052 early supermassive black holes, 713 00:38:09,153 --> 00:38:12,055 we must look back at the very beginning. 714 00:38:12,156 --> 00:38:15,125 Soon after the Big Bang, 715 00:38:15,226 --> 00:38:18,695 the first particles form, cool, and become 716 00:38:18,796 --> 00:38:20,597 electrically charged. 717 00:38:20,698 --> 00:38:21,931 Things were very different, 718 00:38:22,033 --> 00:38:23,667 radically different than they are now. 719 00:38:23,768 --> 00:38:25,468 Particles were whizzing by each other. 720 00:38:25,569 --> 00:38:26,870 Everything was charged. 721 00:38:26,971 --> 00:38:29,372 It was just a very different landscape. 722 00:38:29,473 --> 00:38:32,575 ROWE: There are no stars yet, not even atoms. 723 00:38:32,677 --> 00:38:35,745 But some scientists think moving charged 724 00:38:35,846 --> 00:38:39,482 particles created the first magnetic fields. 725 00:38:39,583 --> 00:38:40,784 Magnetic fields were essentially 726 00:38:40,885 --> 00:38:42,952 everywhere in the early universe. 727 00:38:43,054 --> 00:38:45,855 PONTZEN: Those magnetic fields would have extended extremely 728 00:38:45,956 --> 00:38:49,192 large distances, like a very finely 729 00:38:49,293 --> 00:38:52,128 spun web all through the early universe. 730 00:38:53,364 --> 00:38:58,234 ROWE: Gradually, atoms form and gather into clouds of gas. 731 00:38:58,336 --> 00:39:00,103 These will become the first 732 00:39:00,204 --> 00:39:04,808 galaxies and their supermassive black holes. 733 00:39:04,909 --> 00:39:08,111 During this time, magnetic fields change. 734 00:39:08,212 --> 00:39:11,614 They bunch together around the forming galaxies. 735 00:39:11,716 --> 00:39:12,882 But we don't know how. 736 00:39:12,983 --> 00:39:15,151 PONTZEN: The thing with magnetic fields is 737 00:39:15,252 --> 00:39:17,387 they're extremely hard to predict, 738 00:39:17,488 --> 00:39:21,124 and you need to do really hard calculations that, even now, 739 00:39:21,225 --> 00:39:22,926 we're only just starting to do. 740 00:39:23,994 --> 00:39:27,130 ROWE: 2017 -- scientists design 741 00:39:27,231 --> 00:39:28,865 a groundbreaking computer model 742 00:39:28,966 --> 00:39:33,036 that simulates patterns of magnetism developing over time. 743 00:39:33,137 --> 00:39:38,007 The images show lines of magnetic force getting stronger 744 00:39:38,109 --> 00:39:41,411 and more focused across a vast region of space. 745 00:39:41,512 --> 00:39:45,148 Some astronomers think these emerging magnetic field lines 746 00:39:45,216 --> 00:39:49,686 help shape early galaxies and the supermassive black holes 747 00:39:49,787 --> 00:39:51,354 at their cores. 748 00:39:51,455 --> 00:39:55,558 Magnetic fields have this ability to push material around. 749 00:39:55,659 --> 00:39:59,629 So one possibility is they could actually help push 750 00:39:59,730 --> 00:40:02,065 or funnel material in towards 751 00:40:02,166 --> 00:40:05,702 a growing black hole and help it grow faster than it would 752 00:40:05,803 --> 00:40:07,404 do otherwise. 753 00:40:07,505 --> 00:40:10,240 ROWE: In today's universe, we know magnetic fields 754 00:40:10,341 --> 00:40:13,843 around planets can deflect dust particles. 755 00:40:13,944 --> 00:40:16,045 On much larger scales, 756 00:40:16,147 --> 00:40:19,349 matter may also have been channeled into the centers of 757 00:40:19,450 --> 00:40:21,584 galaxies of the early universe. 758 00:40:21,685 --> 00:40:23,052 Were the magnetic fields of 759 00:40:23,154 --> 00:40:25,855 these early galaxies a conduit that you could get matter 760 00:40:25,956 --> 00:40:28,691 dumped more and more into the middle and maybe build up 761 00:40:28,793 --> 00:40:29,926 a really big black hole? 762 00:40:31,429 --> 00:40:33,463 ROWE: Scientists are just starting to figure out 763 00:40:33,564 --> 00:40:37,801 the effects of magnetism at the beginning of the universe, 764 00:40:37,902 --> 00:40:40,370 but it could have been one of several mechanisms that 765 00:40:40,471 --> 00:40:42,605 influenced the size of early 766 00:40:42,706 --> 00:40:45,508 supermassive black holes. 767 00:40:45,609 --> 00:40:48,478 PONTZEN: We have lots of ideas for how you might be able 768 00:40:48,579 --> 00:40:50,447 to form supermassive black holes, 769 00:40:50,548 --> 00:40:54,184 but until we see actual mechanisms in action, we just 770 00:40:54,285 --> 00:40:58,488 can't really say which of them are the most important routes. 771 00:40:58,589 --> 00:41:01,891 ROWE: Maybe some other mechanism we haven't even thought of 772 00:41:01,992 --> 00:41:03,359 explains how the early 773 00:41:03,461 --> 00:41:08,164 supermassive black holes got so big so fast. 774 00:41:08,265 --> 00:41:10,767 Hopefully, one day, these monsters of 775 00:41:10,868 --> 00:41:15,138 the cosmos will reveal their secrets to us. 776 00:41:15,239 --> 00:41:18,508 Supermassive black hole research is utterly 777 00:41:18,609 --> 00:41:21,077 mind-blowing to me. I mean, this is so cool. 778 00:41:21,178 --> 00:41:23,513 MINGARELLI: It's important to explain how these early 779 00:41:23,614 --> 00:41:25,582 supermassive black holes formed 780 00:41:25,683 --> 00:41:29,018 in order to have a really concrete understanding of how 781 00:41:29,119 --> 00:41:30,353 the universe works. 782 00:41:32,223 --> 00:41:35,325 Supermassive black holes are the great engines of cosmic 783 00:41:35,426 --> 00:41:38,361 change -- they're enormous points of matter, 784 00:41:38,462 --> 00:41:40,663 and because they're just so massive, 785 00:41:40,764 --> 00:41:43,433 they can sculpt the evolution of galaxies. 786 00:41:43,534 --> 00:41:44,968 They're the master key 787 00:41:45,069 --> 00:41:48,338 to most of the unsolved mysteries in physics. 788 00:41:48,439 --> 00:41:50,106 We have a chance here 789 00:41:50,207 --> 00:41:52,375 to understand supermassive black holes 790 00:41:52,476 --> 00:41:55,345 so that we can understand the formation of galaxies, 791 00:41:55,446 --> 00:41:58,147 the generation of stars like our sun, and maybe even 792 00:41:58,249 --> 00:41:59,616 the appearance of life.