Dr Daniel Whalen

Scientists discover how the universe’s first quasars formed

The mystery of how the universe’s first quasars formed — something that has baffled scientists for nearly 20 years — has now been solved by a team of astrophysicists whose findings are published today in Nature.

The existence of more than 200 quasars powered by supermassive black holes less than a billion years after the Big Bang had remained one of the biggest problems in astrophysics as it was never fully understood how they formed so early.

The team of experts led by Dr Daniel Whalen of the University of Portsmouth have discovered that the first quasars formed naturally in the violent, turbulent conditions of rare gas reservoirs in the early Universe.

The first supermassive black holes were simply a natural result of structure formation in cold dark matter cosmologies – children of the cosmic web.

dr. Whalen, from university Institute of Cosmology and Gravitationsaid: “This discovery is particularly exciting because it has destroyed 20 years of thinking about the origin of the universe’s first supermassive black holes.

“We find supermassive black holes at the centers of most massive galaxies today, which can be millions or billions of times the mass of the sun. But in 2003, we started finding quasars — highly luminous, actively accumulating supermassive black holes that resemble cosmic lighthouses in the early universe – that existed less than a billion years after the big bang, and no one understood how they formed at such an early time.”

A few years ago, supercomputer simulations showed that early quasars could form at the intersections of rare, cold, powerful gas flows. Only a dozen of these existed in a space volume of one billion light-years across, but the black hole was supposed to have 100,000 solar masses at birth. Black holes today form when massive stars run out of fuel and collapse, but they are usually only 10-100 solar masses.

Astrophysicists had long theorized that 10,000 to 100,000 solar-mass stars formed in the early Universe, but only in exotic, finely tuned environments such as strong ultraviolet backgrounds or supersonic flows between gas and dark matter that did not resemble the turbulent clouds in which the first quasars. formed.

A supercomputer simulation of the birth of a primeval quasar.  Image shows small red dots on a central green and yellow color spot on a blue background

A supercomputer simulation of the birth of an primordial quasar

dr. Whalen said: “We think of these stars as a bit like dinosaurs on Earth, they were huge and primitive. And they had short lives, only living a quarter of a million years before collapsing into black holes.

“Our supercomputer models went back to very early times and found that the cold, dense gas flows capable of growing a billion black holes by the mass of the Sun in just a few hundred million years created their own supermassive stars without that required an unusual environment.The cold currents created turbulence in the cloud that prevented normal stars from forming until the cloud became so massive that it collapsed catastrophically under its own weight, forming two giant primordial stars – one with a mass of 30,000 suns and another with a mass of 40,000.

As a result, the only primeval clouds that could form a quasar just after cosmic dawn — when the first stars in the universe formed — also easily created their own massive seeds. This simple, beautiful result explains not only the origin of the first quasars. , but also their demographics – their numbers in early times.

“The first supermassive black holes were simply a natural result of structure formation in cold dark matter cosmologies — children of the cosmic web.”

The article The Turbulent Origins of the First Quasars has been published in: Nature

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