Over the past few years, as we’ve been able to dig deeper into the early universe, astronomers have discovered something very disturbing.
The universe is a billion years old, and supermassive black holes up to a billion times the mass of the Sun have already formed. Based on what we know about black hole formation and growth, explaining the existence and size of this supergiant is a major challenge. How did they get there after the Big Bang? How were they exposed to such a great danger?
Now, supercomputer simulations have revealed a look that explains how they formed without the need for exotic conditions: rare reservoirs of cold, turbulent gas that have collapsed into stars larger than anything in the universe today. These could have been large seeds that grew into supermassive black holes.
“Today we find supermassive black holes in the centers of the most massive galaxies, which may be millions or billions of times the mass of the Sun. But in 2003 we began discovering quasars – extremely bright black holes that are actively accumulating. Cosmic beacons in the early universe – a billion years after the Big Bang. was less,” Astronomer Daniel Wallen said: from the University of Portsmouth in England.
“No one understood how they formed so early. This discovery is very exciting because it upends 20 years of thinking about the origin of the universe’s first supermassive black holes.”
There are two main schools of thought about how supermassive black holes form. The first is the bottom-up model. A massive star dies, leaving behind a black hole with a mass 100 times the mass of the Sun.
Over time — lots and lots of time — the black hole sucks up an array of material and grows bigger and bigger, millions to billions of times the size of the Sun. Quasars in the early universe are difficult to reconcile.
The other option is if you start with a “seed” of a supermassive black hole, more than 100,000 times the mass of the Sun. The stars that collapsed to form these black holes would really have lived a very short cosmic life, perhaps 250,000 years, before collapsing into the black hole.
there There are not many stars todayWe do not know the current generation mechanism that can generate it. But the simulations show that in the early universe, when conditions were different from the current ones, such stars could theoretically have formed at rare but powerful junctions of dense, turbulent streams and cold gas.
Cosmologists thought it would take some really strange conditions, like strong ultraviolet backgrounds or supersonic flows between gas and dark matter. None of these strange conditions resemble the environments in which these early cosmic quasars were discovered.
Led by astrophysicist Mohammed Latif from the United Arab Emirates University, the researchers ran simulations of gas currents and were delighted to discover that supermassive black holes formed spontaneously at the intersections of these currents without the need for natural conditions. .
In the simulation, the turbulence caused by the cross currents prevented the normal stars we see today from forming. This usually happens when a dense knot of material in a cold cloud collapses under the influence of gravity to form a young star, but when there is a lot of turbulence, conditions are not stable enough for this to happen.
Ultimately, however, the cloud in the simulation grew so large that it disastrously collapsed into two massive stars, 31,000 and 40,000 times the mass of the Sun.
As gas continues to flow from the currents into the clouds, a black hole with a mass billions of times the mass of the Sun will form and grow over a few hundred million years.
“As a result, when the first stars of the universe formed — the only primordial clouds capable of producing quasars after the cosmic dawn — they conveniently formed their own massive seeds. This simple and beautiful result not only explains the origin of the first quasars. Its population – their early numbers,” Whalen . concluded.
“The first supermassive black holes were a cosmological cosmological consequence of cold dark matter – the nascent structure of the cosmic web.”
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