wp-plugin-hostgator domain was triggered too early. This is usually an indicator for some code in the plugin or theme running too early. Translations should be loaded at the init action or later. Please see Debugging in WordPress for more information. (This message was added in version 6.7.0.) in /home4/scienrds/scienceandnerds/wp-includes/functions.php on line 6114ol-scrapes domain was triggered too early. This is usually an indicator for some code in the plugin or theme running too early. Translations should be loaded at the init action or later. Please see Debugging in WordPress for more information. (This message was added in version 6.7.0.) in /home4/scienrds/scienceandnerds/wp-includes/functions.php on line 6114Source:https:\/\/www.quantamagazine.org\/jwst-spots-giant-black-holes-all-over-the-early-universe-20230814\/#comments<\/a><\/br> Years before she was even sure the James Webb Space Telescope<\/a> would successfully launch, Christina Eilers<\/a> started planning a conference for astronomers specializing in the early universe. She knew that if \u2014 preferably, when \u2014 JWST started making observations, she and her colleagues would have a lot to talk about. Like a time machine, the telescope could see farther away and farther into the past than any previous instrument.<\/p>\n Fortunately for Eilers (and the rest of the astronomical community), her planning was not for naught: JWST launched and deployed without a hitch, then started scrutinizing the early universe in earnest from its perch in space a million miles away.<\/p>\n In mid-June, about 150 astronomers gathered at the Massachusetts Institute of Technology for Eilers\u2019 JWST \u201cFirst Light\u201d conference. Not quite a year had passed since JWST started sending images<\/a> back to Earth. And just as Eilers had anticipated, the telescope was already reshaping astronomers\u2019 understanding of the cosmos\u2019s first billion years.<\/p>\n One set of enigmatic objects stood out in the myriad presentations. Some astronomers called them \u201chidden little monsters.\u201d To others, they were \u201clittle red dots.\u201d But whatever their name, the data was clear: When JWST stares at young galaxies \u2014 which appear as mere red specks in the darkness \u2014 it sees a surprising number with cyclones churning in their centers.<\/p>\n \u201cThere seems to be an abundant population of sources we didn\u2019t know about,\u201d said Eilers, an astronomer at MIT, \u201cwhich we didn\u2019t anticipate finding at all.\u201d<\/p>\n In recent months, a torrent of observations of the cosmic smudges has delighted and confounded astronomers.<\/p>\n \u201cEverybody is talking about these little red dots,\u201d said Xiaohui Fan<\/a>, a researcher at the University of Arizona who has spent his career searching for distant objects in the early universe.<\/p>\n The most straightforward explanation for the tornado-hearted galaxies is that large black holes weighing millions of suns are whipping the gas clouds into a frenzy. That finding is both expected and perplexing. It is expected because JWST was built, in part, to find the ancient objects. They are the ancestors of billion-sun behemoth black holes that seem to appear in the cosmic record inexplicably early. By studying these precursor black holes, such as three record-setting youngsters discovered this year, scientists hope to learn where the first humongous black holes came from and perhaps identify which of two competing theories better describes their formation: Did they grow extremely rapidly, or were they simply born big? Yet the observations are also perplexing because few astronomers expected JWST to find so many young, hungry black holes \u2014 and surveys are turning them up by the dozen. In the process of attempting to solve the former mystery, astronomers have uncovered a throng of bulky black holes that may rewrite established theories of stars, galaxies and more.<\/p>\n \u201cAs a theorist, I have to build a universe,\u201d said Marta Volonteri<\/a>, an astrophysicist specializing in black holes at the Paris Institute of Astrophysics. Volonteri and her colleagues are now contending with the influx of giant black holes in the early cosmos. \u201cIf they are [real], they completely change the picture.\u201d<\/p>\n The JWST observations are shaking up astronomy in part because the telescope can detect light reaching Earth from deeper in space than any earlier machine.<\/p>\n \u201cWe built this absurdly powerful telescope over 20 years,\u201d said Grant Tremblay<\/a>, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics. \u201cThe whole point of it originally was to look deep into cosmic time.\u201d<\/p>\n One of the mission\u2019s goals is to catch galaxies in the act of forming during the universe\u2019s first billion years (out of its roughly 13.8-billion-year history). The telescope\u2019s initial observations from last summer hinted at a young universe<\/a> full of strikingly mature galaxies, but the information astronomers could wring from such images was limited. To really understand the early universe, astronomers needed more than just the images; they hungered for the spectra of those galaxies \u2014 the data that comes in when the telescope breaks incoming light into specific hues.<\/p>\n Galactic spectra, which JWST started to send back in earnest at the end of last year, are useful for two reasons.<\/p>\n First, they let astronomers nail down the galaxy\u2019s age. The infrared light JWST collects is reddened, or redshifted, meaning that as it traverses the cosmos, its wavelengths are stretched by the expansion of space. The extent of that redshift lets astronomers determine a galaxy\u2019s distance, and therefore when it originally emitted its light. Nearby galaxies have a redshift of almost zero. JWST can handily make out objects beyond a redshift of 5, which corresponds to roughly 1 billion years after the Big Bang. Objects at higher redshifts are significantly older and farther away.<\/p>\n Second, spectra give astronomers a sense of what\u2019s happening in a galaxy. Each hue marks an interaction between photons and specific atoms (or molecules). One color originates from a hydrogen atom flashing as it settles down after a bump; another indicates jostled oxygen atoms, and another nitrogen. A spectrum is a pattern of colors that reveals what a galaxy is made of and what those elements are doing, and JWST is providing that crucial context for galaxies at unprecedented distances.<\/p>\n \u201cWe\u2019ve made such a huge leap,\u201d said Aayush Saxena<\/a>, an astronomer at the University of Oxford. The fact that \u201cwe\u2019re talking about chemical composition of redshift 9 galaxies is just absolutely remarkable.\u201d<\/p>\n (Redshift 9 is mind-bogglingly distant, corresponding to a time when the universe was a mere 0.55 billion years old.)<\/p>\n Galactic spectra are also perfect tools for finding a major perturber of atoms: giant black holes that lurk at the hearts of galaxies. Black holes themselves are dark, but when they feed on gas and dust, they rip atoms apart, making them beam out telltale colors. Long before JWST\u2019s launch, astrophysicists hoped the telescope would help them spot those patterns and find enough of the early universe\u2019s biggest and most active black holes to solve the mystery of how they formed.<\/p>\n The mystery began more than 20 years ago, when a team led by Fan spotted one of the most distant galaxies<\/a> ever observed \u2014 a brilliant quasar, or a galaxy anchored to an active supermassive black hole weighing perhaps billions of suns. It had a redshift of 5, corresponding to around 1.1 billion years after the Big Bang. With further sweeps of the sky, Fan and his colleagues repeatedly broke their own records, pushing the quasar redshift frontier to 6 in 2001<\/a> and eventually to 7.6 in 2021<\/a> \u00ad\u00ad\u2014 just 0.7 billion years after the Big Bang.<\/p>\n The problem was that making such gigantic black holes seemed impossible so early in cosmic history.<\/p>\n Like any object, black holes take time to grow and form. And like a 6-foot-tall toddler, Fan\u2019s supersize black holes were too big for their age \u2014 the universe wasn\u2019t old enough for them to have accrued billions of suns of heft. To explain those overgrown toddlers, physicists were forced to consider two distasteful options.<\/p>\n The first was that Fan\u2019s galaxies started off filled with standard, roughly stellar-mass black holes of the sort supernovas often leave behind. Those then grew both by merging and by swallowing up surrounding gas and dust. Normally, if a black hole feasts aggressively enough, an outpouring of radiation pushes away its morsels. That stops the feeding frenzy and sets a speed limit for black hole growth that scientists call the Eddington limit. But it\u2019s a soft ceiling: A constant torrent of dust could conceivably overcome the outpouring of radiation. However, it\u2019s hard to imagine sustaining such \u201csuper-Eddington\u201d growth for long enough to explain Fan\u2019s beasts \u2014 they would have had to bulk up unthinkably fast.<\/p>\n Or perhaps black holes can be born improbably large. Gas clouds in the early universe may have collapsed directly into black holes weighing many thousands of suns \u2014 producing objects called heavy seeds. This scenario is hard to stomach too, because such large, lumpy gas clouds should fracture into stars before forming a black hole.<\/p>\n One of JWST\u2019s priorities is to evaluate these two scenarios by peering into the past and catching the fainter ancestors of Fan\u2019s galaxies. These precursors wouldn\u2019t quite be quasars, but galaxies with somewhat smaller black holes on their way to becoming quasars. With JWST, scientists have their best chance of spotting black holes that have barely started to grow \u2014 objects that are young enough and small enough for researchers to nail down their birth weight.<\/p>\n That\u2019s one reason a group of astronomers with the Cosmic Evolution Early Release Science Survey, or CEERS, led by Dale Kocevski of Colby College, started working overtime when they first noticed signs of such young black holes popping up in the days following Christmas.<\/p>\n \u201cIt\u2019s kind of impressive how many of these there are,\u201d wrote Jeyhan Kartaltepe<\/a>, an astronomer at the Rochester Institute of Technology, during a discussion on Slack.<\/p>\n \u201cLots of little hidden monsters,\u201d Kocevski replied.<\/p>\n In the CEERS spectra, a few galaxies immediately leapt out as potentially hiding baby black holes \u2014 the little monsters. Unlike their more vanilla siblings, these galaxies emitted light that didn\u2019t arrive with just one crisp shade for hydrogen. Instead, the hydrogen line was smeared, or broadened, into a range of hues, indicating that some light waves were squished as orbiting gas clouds accelerated toward JWST (just as an approaching ambulance emits a rising wail as its siren\u2019s soundwaves are compressed) while other waves were stretched as clouds flew away. Kocevski and his colleagues knew that black holes were just about the only object capable of slinging hydrogen around like that.<\/p>\n \u201cThe only way to see the broad component of the gas orbiting the black hole is if you\u2019re looking right down the barrel of the galaxy and right into the black hole,\u201d Kocevski said.<\/p>\n By the end of January, the CEERS team had managed to crank out a preprint describing two of the \u201chidden little monsters,\u201d as they called them. Then the group set out to systematically study a wider swath of the hundreds of galaxies collected by their program to see just how many black holes were out there. But they got scooped by another team, led by Yuichi Harikane of the University of Tokyo, just weeks later. Harikane\u2019s group searched 185 of the most distant CEERS galaxies and found 10<\/a> with broad hydrogen lines \u2014 the likely work of million-solar-mass central black holes at redshifts between 4 and 7. Then in June, an analysis of two other surveys led by Jorryt Matthee<\/a> of the Swiss Federal Institute of Technology Zurich identified 20 more \u201clittle red dots<\/a>\u201d with broad hydrogen lines: black holes churning around redshift 5. An analysis posted in early August<\/a> announced another dozen, a few of which may even be in the process of growing by merging.<\/p>\n \u201cI\u2019ve been waiting for these things for so long,\u201d Volonteri said. \u201cIt\u2019s been incredible.\u201d<\/p>\n But few astronomers anticipated the sheer number of galaxies with a big, active black hole. The baby quasars in JWST\u2019s first year of observations are more numerous than scientists had predicted based on the census of adult quasars<\/a> \u2014 between 10 times and 100 times more abundant.<\/p>\n<\/div>\n <\/br><\/br><\/br><\/p>\n
\nJWST Spots Giant Black Holes All Over the Early Universe<\/br>
\n2023-08-15 21:58:34<\/br><\/p>\nA Cosmic Time Machine <\/strong><\/h2>\n
Too Big, Too Early<\/strong><\/h2>\n
A Growing Crowd of Monsters <\/strong><\/h2>\n