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UH scientist on team that discovered 'baby black holes'

By Gregg K. Kakesako

POSTED:
LAST UPDATED: 11:11 a.m. HST, Jun 15, 2011


 

A team of astrophysicists, including one from the University of Hawaii, have found the first evidence of baby black holes created at the dawn of the universe.

"Until now, we had no idea what the black holes in these early galaxies were doing, or if they even existed," said Ezequiel Treister of the UH, lead author of the study appearing in the June 16 issue of the journal Nature. "Now we know they are there, and they are growing like gangbusters."

The astrophysicists used NASA's orbiting Chandra X-ray Observatory and found the first direct evidence that massive black holes were common in the early universe, according to a NASA news release. Black holes occur when stars implode, creating a gravitation collapse that collects and compresses mass in such a way that no light waves can escape.

Scientists believe that the black holes are growing in connection with the galaxies where they were found and that very young black holes grew more aggressively than previously thought, in tandem with the growth of their host galaxies.

By pointing Chandra at a patch of sky for more than six weeks, NASA said astronomers obtained what is known as the Chandra Deep Field South. When combined with very deep optical and infrared images from NASA's Hubble Space Telescope, the new Chandra data allowed astronomers to search for black holes in 200 distant galaxies, from when the universe was between about 800 million to 950 million years old.

A population of young black holes in the early universe had been predicted, but not yet observed. Detailed calculations show that the total amount of black hole growth observed by this team is about a hundred times higher than recent estimates, NASA said.

Because these black holes are nearly all enshrouded in thick clouds of gas and dust, optical telescopes frequently cannot detect them. However, the high energies of X-ray light can penetrate these veils, allowing the black holes inside to be studied.

At the news conference Treister said "we found evidence of a very large number of massive black holes when the universe  was less than a billion light years old."

Scientists in the past have estimated that the universe is estimated at 13.7 billion years.

The super-sized growth means that the black holes in the CDFS are less extreme versions of quasars -- luminous, rare objects powered by material falling onto supermassive black holes., NASA said. However, the sources in the CDFS are about a hundred times fainter and the black holes are about a thousand times less massive than the ones in quasars, officials said. The observations found that between 30 and 100 percent of the distant galaxies contain growing supermassive black holes. Extrapolating these results from the small observed field to the full sky, there are at least 30 million supermassive black holes in the early universe. This is a factor of 10,000 larger than the estimated number of quasars in the early universe, according to NASA.

Treister said the "most exciting" thing about his team's finding was that "we found about a 100 times more growth in black hole growth in the universe" than what was known before.







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