NASA'S Chandra Finds Massive Black Holes Common In Early Universe

WASHINGTON -- Using the deepest X-ray image ever taken, astronomers
found the first direct evidence that massive black holes were common
in the early universe. This discovery from NASA's Chandra X-ray
Observatory shows 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,
astronomers obtained what is known as the Chandra Deep Field South
(CDFS). 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.

"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 University of Hawaii, 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 super-sized growth means that the black holes in the CDFS are less
extreme versions of quasars -- very luminous, rare objects powered by
material falling onto supermassive black holes. 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.

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.

"It appears we've found a whole new population of baby black holes,"
said co-author Kevin Schawinski of Yale University. "We think these
babies will grow by a factor of about a hundred or a thousand,
eventually becoming like the giant black holes we see today almost 13
billion years later."

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.

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.

Physicists studying black holes want to know more how the first
supermassive black holes were formed and how they grow. Although
evidence for parallel growth of black holes and galaxies has been
established at closer distances, the new Chandra results show that
this connection starts earlier than previously thought, perhaps right
from the origin of both.

"Most astronomers think in the present-day universe, black holes and
galaxies are somehow symbiotic in how they grow," said Priya
Natarajan, a co-author from Yale University. "We have shown that this
codependent relationship has existed from very early times."

It has been suggested that early black holes would play an important
role in clearing away the cosmic "fog" of neutral, or uncharged,
hydrogen that pervaded the early universe when temperatures cooled
down after the Big Bang. However, the Chandra study shows that
blankets of dust and gas stop ultraviolet radiation generated by the
black holes from traveling outwards to perform this "reionization."
Therefore, stars and not growing black holes are likely to have
cleared this fog at cosmic dawn.

Chandra is capable of detecting extremely faint objects at vast
distances, but these black holes are so obscured that relatively few
photons can escape and hence they could not be individually detected.
Instead, the team used a technique that relied on Chandra's ability
to accurately determine the direction from which the X-rays came to
add up all the X-ray counts near the positions of distant galaxies
and find a statistically significant signal.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the
Chandra program for the agency's Science Mission Directorate in
Washington. The Smithsonian Astrophysical Observatory controls
Chandra's science and flight operations from Cambridge, Mass.

More information, including images and other multimedia, can be found at:

http://www.nasa.gov/chandra

and

http://chandra.si.edu

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