An artist's illustration of the view into a black hole. (Credit: April Hobart, NASA, Chandra X-Ray Observatory)

ScienceDaily (Nov. 25, 2009) — The first large black holes in the universe likely formed and grew deep inside gigantic, starlike cocoons that smothered their powerful x-ray radiation and prevented surrounding gases from being blown away, says a new study led by the University of Colorado at Boulder.

The formation process involved two stages, said Mitchell Begelman, a professor and the chair of CU-Boulder's astrophysical and planetary sciences department. The predecessors to black hole formation, objects called supermassive stars, probably started forming within the first few hundred million years after the Big Bang some 14 billion years ago. A supermassive star eventually would have grown to a huge size — as much as tens of millions of times the mass of our sun — and would have been short-lived, with its core collapsing in just in few million years, he said.

In the new study to be published in Monthly Notices of the Royal Astronomical Society in London, Begelman calculated how supermassive stars might have formed, as well as the masses of their cores. These calculations allowed him to estimate their subsequent size and evolution, including how they ultimately left behind "seed" black holes.

Begelman said the hydrogen-burning supermassive stars would had to have been stabilized by their own rotation or some other form of energy like magnetic fields or turbulence in order to facilitate the speedy growth of black holes at their centers. "What's new here is we think we have found a new mechanism to form these giant supermassive stars, which gives us a new way of understanding how big black holes may have formed relatively fast," said Begelman.

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