New research shows that dark matter decay can help black holes reach monstrous sizes relatively early in the infant universe. If true, this could help explain some of the most puzzling observations of the universe by the James Webb Space Telescope.
Since the James Webb Space Telescope (JWST) began sending data back to Earth in the summer of 2022, supermassive black holes with masses millions or even billions of times the mass of the Sun have been discovered as early as 500 million years after life. of the 13.8-billion-year-old universe has baffled scientists. That is why it should last at least 1 billion years for black holes to reach the “supermassive state”.
One hypothesis to explain how primordial black holes begin to grow suggests that they were born directly from massive clouds of gas and dust. However, this new research suggests that dark matter, the most mysterious substance in the universe, was the catalyst for this process.
“The formation of supermassive black holes is a mystery. Finding supermassive black holes when the universe was less than 1 billion years old is like finding mammal bones among dinosaur bones in a Jurassic sedimentary rock,” said Alexander Kosenko, a member of the research team. ” an astrophysicist from the University of California, Los Angeles (UCLA), told Space.com. “These observations require a very different explanation of the formation of supermassive black holes.
We found that radiation from dark matter decay can cause some large gas clouds to collapse into supermassive black holes, solving the mystery of their origins.
Related: Dark matter can play a “study maker” for massive black holes
Solving one puzzle with another puzzle
Dark matter is currently considered one of the biggest outstanding mysteries in physics because, despite making up about 85% of the matter in the universe, scientists don’t know what it is.
Researchers know that dark matter cannot be made of the same “stuff” that makes up the atoms that make up the ordinary matter of stars, planets, moons, asteroids, and our bodies. This is because dark matter does not appear to interact with electromagnetic radiation (light), whereas electrons, protons, and neutrons actually do.
This lack of interaction with light also frustratingly makes dark matter effectively invisible to us, as scientists can only infer its presence through its interaction with gravity and the effects of this interaction on ordinary matter and light.
Dark matter may not interact with light, but one of the proposed properties of this matter in some models is the decay of its more unstable particles—which release photons, the fundamental particles of light. The team thinks this radiation could be the missing piece of the supermassive black hole puzzle.
“Gravity can compress a cloud of gas and force it to collapse, so it seems that a cloud with a mass of a million solar masses can lead to the formation of a black hole with a mass of a million solar masses,” Kosenko explained. “In reality, this doesn’t happen because gravity works on all distance scales, causing small parts of a large cloud to collapse first before the whole cloud has a chance to collapse. So instead of A giant black hole, we end up with a bunch of smaller gas clouds.”
He added that if there was something to counteract the action of gravity at short distances, without affecting the collapse at long distances, this could cause a “direct collapse” of a huge volume of gas into a supermassive black hole. And what can counter gravity is pressure.
“If a gas cloud stays hot for a long time, it cannot split into smaller haloes because the hot gas has more pressure and is strong enough to resist the pull of gravity,” Kusenko continued. This is true as long as the temperature is high enough. However, if the gas cools, the pressure decreases and gravity can prevail in many small regions, which collapse into dense bodies before gravity has a chance to pull the entire cloud into one unit. black hole.”
This cooling occurs because even though the vast majority of gas in the early universe consisted of hydrogen atoms. The stars have not yet had a chance to forge heavier elements and disperse them with supernova explosions. Most of these endless hydrogen atoms bounce off each other like billiard balls unless they are attached to a molecule with rotational energy levels that can be excited by atomic collisions.
Then the excited molecule can radiate energy and return to its initial state and prepare for another interaction with the hydrogen atom. Kusenko added: Cooling is faster. Dark matter particles can decay and produce radiation that can decay [or break down] Hydrogen molecules.
Therefore, the radiation from the decaying dark matter could give the massive gas clouds in the early universe the opportunity to collapse and give birth to the first massive black holes.
“If this happens, the direct collapse of hot gas into supermassive black holes becomes possible,” Kosenko added.
Should this be proven if it tells us something about dark matter itself?
“There are two possibilities: either the dark matter particles can decay very slowly, or the dark matter may contain a small component that decays quickly, while the rest of the dark matter is stable,” Kosenko said. “In any case, the properties of the radiation required to create black holes tell us the mass of the decaying dark matter particles. This could help discover or rule out this scenario.
The team’s research was published on August 27 in the journal Physical Review Letters.
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