The James Webb Space Telescope (JWST) keeps finding supermassive black holes (SMBH) in the early Universe. They\u2019re in active galactic nuclei seen only 500,000 years after the Big Bang. This was long before astronomers thought they could exist. What\u2019s going on?<\/p>\n
<\/p>\n Monster black holes like the ones at the hearts of galaxies take a really long time to grow so massive. They could start as smaller ones that gobble up nearby stars and gases, or they can grow by merging with other supermassive black holes. That typically takes billions of years and a lot of material to build up to something as massive as the four-million-solar-mass one in the heart of our Milky Way Galaxy. It\u2019s even longer for the really big ones that contain tens of millions of stellar masses.<\/p>\n JWST has spotted many SMBH that already appear \u201cold\u201d and massive less than a billion years after the Big Bang. It\u2019s not an observational fluke\u2014they\u2019re really there. <\/p>\n \u201cHow surprising it has been to find a supermassive black hole with a billion-solar-mass when the universe itself is only half a billion years old,\u201d said astrophysicist Alexander Kusenko, a professor of physics and astronomy at UCLA. \u201cIt\u2019s like finding a modern car among dinosaur bones and wondering who built that car in the prehistoric times.\u201d<\/p>\n So, what built SMBH so early in cosmic history? One obvious process is the death of the first Population III stars that began forming as soon as the infant Universe cooled enough for them to coalesce. These were massive, metal-poor (meaning they had no elements heavier than helium), and short-lived. When they died as supernovae, they formed stellar-mass black holes. It\u2019s possible those early ones merged and got bigger.<\/p>\n Another suggestion is a so-called \u201cgravo-thermal\u201d collapse of self-interacting dark matter halos. That basically means a negative heat transfer inside a system. That can lead to the collapse of a black hole, and from there, it could have grown.<\/p>\n Astronomers have also considered the participation of primordial black holes created in the moments after the Big Bang. These theoretical low-mass black holes could have formed under special conditions when dense areas of space collapsed quickly. How SMBH formed from primordial black holes isn\u2019t understood at the moment. So, is there another formation theory?<\/p>\n This is where dark matter comes into play. Kusenko and his colleagues dug into the idea of dark matter-influenced collapse. They found that if dark matter decays, it plays a role in \u201ccorraling\u201d a hydrogen gas cloud. It would not fragment (as clouds usually do). Eventually, that could lead to the relatively rapid formation of an SMBH. Since there is evidence of dark matter\u2019s influence in the early Universe, this could explain the monster black holes in the earliest epochs of cosmic history.<\/p>\n Of course, the conditions have to be just right for this to happen. \u201cHow quickly the gas cools has a lot to do with the amount of molecular hydrogen,\u201d said doctoral student Yifan Lu, the first author on a paper describing the dark matter idea. \u201cHydrogen atoms bonded together in a molecule dissipate energy when they encounter a loose hydrogen atom. The hydrogen molecules become cooling agents as they absorb thermal energy and radiate it away. Hydrogen clouds in the early universe had too much molecular hydrogen, and the gas cooled quickly and formed small halos instead of large clouds.\u201d<\/p>\n Certain radiation can destroy molecular hydrogen. That creates conditions that prevent cloud fragmentation. The radiation could be from somewhere, and Lu and others suggest an interesting idea in their paper. They state that there\u2019s a possible \u201cparameter space\u201d where relic decaying particles could emit radiation that would spur the collapse. Among other things, they propose an \u201caxion-like\u201d dark matter particle decaying and spurring the eventual coalescence of a cloud of hydrogen into an SMBH.<\/p>\n Dark matter itself is a mysterious \u201cstuff\u201d that makes up a very large part of the \u201cstuff\u201d of the Universe. We know about it from its gravitational effects on the objects we can see (called baryonic matter). The form that dark matter takes isn\u2019t understood at all, however. It could be made of particles that slowly decay, or it could be made of more than one particle species. Some could be stable, others could decay at early times. In either case, the product of decay could be radiation in the form of photons, which break up molecular hydrogen and prevent hydrogen clouds from cooling too quickly. Even very mild decay of dark matter yielded enough radiation to prevent cooling, forming large clouds and, eventually, supermassive black holes.<\/p>\n Of course, this idea hasn\u2019t been proven. However, the team points out that the decay of such particles of dark matter can emit light in both the optical and ultraviolet spectrum. That might explain the very precise measurements of the \u201ccosmic optical background\u201d (COB) seen by the New Horizons LORRI instrument. The COB is a visible light background roughly analogous to the cosmic microwave background. Think of it as the sum of all emissions from objects beyond the Milky Way Galaxy. Its presence allows astronomers to diagnose and understand the emissions from all astrophysical objects. There\u2019s still a lot to study and understand about these possible axions (if they make up dark matter).<\/p>\n Dark Matter Could Have Helped Make Supermassive Black Holes in the Early UniverseBuilding Supermassive Black Holes in Ancient Times<\/h3>\n
![\"Primordial](\"https:\/\/www.universetoday.com\/wp-content\/uploads\/2024\/04\/PBH_formation-1024x360.jpg\")
From Cloud to Black Hole Formation via Dark Matter?<\/h3>\n
Mysteries of Dark Matter and SMBH Need Answers<\/h3>\n
For More Information<\/h4>\n
Direct Collapse Supermassive Black Holes from Relic Particle Decay
Pre-print of Paper<\/p>\nLike this:<\/h3>\n