Long-standing mystery of early supermassive black holes is finally solved

(ORDO NEWS) — Over the past few years, as we have been able to look deeper and deeper into the early universe, astronomers have discovered something extremely mysterious.

Before the universe was a billion years old, gigantic black holes, a billion times the mass of the sun, had already somehow formed.

Given what we know about the formation and growth of black holes, it is extremely difficult to explain the presence and size of these giants. How did they get there, so soon after the Big Bang? And how did they get so damn big?

Now, supercomputer simulations have revealed an origin that explains how they formed unnecessarily under exotic conditions: rare reservoirs of turbulent cold gas that collapsed into stars more massive than anything else. in the universe today. These were huge seeds from which supermassive black holes grew.

“Today we find supermassive black holes at the centers of the most massive galaxies, which can be millions or billions of times the mass of the Sun.

But as early as 2003, we began to find quasars – very bright, actively accumulating supermassive black holes, similar to cosmic beacons in the early universe – that existed less than a billion years after the Big Bang, ”said cosmologist Daniel Whalen from the University of Portsmouth. In Great Britain.

“No one understood how they formed at such early times. This discovery is especially exciting because it upended 20 years of knowledge about the origin of the first supermassive black holes in the universe.”

There are two main points of view on how supermassive black holes form. The first is an ascending model. One massive star dies, usually leaving behind a black hole about 100 times the mass of the Sun.

Over time – many, many times – the black hole swallows up a bunch of material that grows larger and larger until it is millions or billions of times the mass of the sun. This is extremely difficult to reconcile with quasars in the early universe.

Another option is if you start with a really big black hole, which is 100,000 times the mass of the Sun. The stars that collapsed to form these black holes lived a very, very short cosmic life, maybe 250,000 years, before collapsing into a black hole.

There are no known stars of this mass today, and we are not aware of any current formation mechanism that could produce them.

But simulations have shown that in the early universe, when conditions were very different from today, such stars could theoretically form at the junctions of rare but powerful flows of dense, turbulent, cold gas.

Cosmologists thought. this would require truly exotic conditions, such as a strong ultraviolet background or supersonic flows between gas and dark matter. And none of these exotic conditions resembled the environment in which these early quasars of the universe were discovered.

Led by astrophysicist Muhammad Latif of the University of the United Arab Emirates in the UAE, the researchers ran simulations of gas flows and were delighted to find that supermassive black holes formed at the intersections of these flows spontaneously, without the need for exotic conditions.

In simulations, the turbulence created by the crossing flows prevents normal stars, such as the ones we see today, from forming.

This usually happens when a dense knot of matter in a cold cloud collapses under gravity to form a young star, but when the turbulence is too great, the conditions are not stable enough for this to happen.

However, in the end, the cloud in the simulation became so massive that it disintegrated catastrophically into two giant stars, whose mass is 31,000 and 40,000 times the mass of the Sun.

As gas from the streams continues to flow into the clouds, a supermassive black hole billions of times the mass of the Sun could form and grow in just a few hundred million years.

“Hence the only primordial clouds that could form a quasar just after the cosmic dawn – when the first stars in the universe formed and also created their own massive seeds. This simple and beautiful result explains not only the origin of the first quasars, but also their demographics – their number in early times, ”concluded Whalen.

“The first supermassive black holes were just a natural consequence of the influence of structure formation in cold dark matter cosmologies – the children of the cosmic web.”


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