Hidden Population of Powerful Black Holes Revealed in Large Sky Survey

According to Donald Schneider, coauthor of the paper and Professor of Astronomy at Penn State, "If one examines a photograph of one of the hidden quasars we discovered, it appears to be just an ordinary galaxy, although quasars are typically are 10 to 100 times more luminous than the Milky Way Galaxy." Schneider is the chair of the SDSS-II science group that studies quasars, which are powered by glowing, super-heated gas as it swirls into black holes a billion times more massive than the Sun.

The research team, which will present its discovery on 9 January 2008 at the annual meeting of the American Astronomical Society in Austin, Texas, has submitted a paper describing the research for publication in the Astronomical Journal. Using the distinctive light-spectrum signature that even highly obscured quasars show as a marker, the SDSS-II team sifted through more than a million spectra to discover 887 hidden quasars, by far the largest sample of these objects ever found.

"A large survey like SDSS-II is important because quasars are about 10,000 times rarer than are normal galaxies," explains Reyes. "We determined how common hidden quasars are, especially the most luminous ones. Perhaps more interestingly, we determined how common they are relative to normal quasars," said team member Nadia Zakamska, a NASA Spitzer Fellow at the Institute for Advanced Study in Princeton. "We found that hidden quasars make up at least half of the quasars in the relatively recent Universe, implying that most of the powerful black holes in our neighborhood had previously been unrecognized."

Michael Strauss of Princeton University explains that powerful black holes are more common in the last eight billion years of cosmic history than had previously been thought. "Moreover, because the light from these hidden quasars previously had been unaccounted for, black holes turn out to be more efficient in converting the energy of in-falling matter into light than we had thought."

This result also has implications for theoretical models of quasars. "The relative numbers of hidden versus normal quasars tell us something about how dust and gas typically are distributed around these objects," explains Julian Krolik, a collaborator from Johns Hopkins University. "If the dust covers a large fraction of the area around a black hole, this object would more likely appear as a hidden quasar. So the large number of hidden quasars discovered by the SDSS team implies that most of the light emitted by quasars is actually obscured."

Source: Penn State University

Missing Black Hole Report: Hundreds Found!
Astronomers have unmasked hundreds of black holes hiding deep inside dusty galaxies billions of light-years away.
Full-spectrum study of small patch of sky yields portrait of maturing universe
A massive project to generate an all-color map of the galaxies in a small area of sky, utilizing four satellite telescopes and four ground-based telescopes, is yielding new information about the universe's "pre-teen" years and the early evolution of galaxies and galaxy clusters.
NASA Performs Headcount of Local Black Holes
NASA scientists using the Swift satellite have conducted the first complete census of galaxies with active, central black holes, a project that scanned the entire sky several times over a nine-month period.
Voracious black holes hide their appetite in dusty galaxies
A UK-led team of astronomers reports today (August 4th) in Nature that they have tracked down an elusive population of black holes growing rapidly hidden behind clouds of dust. Their results suggest that most black hole growth takes place in dusty galaxies, solving astronomer's headaches, as until now, the cosmic x-ray background suggested the existence of more growing black holes than they could find.
NASA's Spitzer Finds Hidden, Hungry Black Holes
Most of the biggest black holes in the universe have been eating cosmic meals behind closed doors – until now.
With its sharp infrared eyes, NASA's Spitzer Space Telescope peered through walls of galactic dust to uncover what may be the long-sought missing population of hungry black holes known as quasars.
NASA's Spitzer Space Telescope Exposes Dusty Galactic Hideouts
How do you hide something as big and bright as a galaxy? You smother it in cosmic dust. NASA's Spitzer Space Telescope saw through such dust to uncover a hidden population of monstrously bright galaxies approximately 11 billion light-years away.

World's Most Powerful Infrared Camera Opens Its Eyes on the Heavens
Stunning image of Orion released

A new astronomical camera has begun operations on the United Kingdom Infrared Telescope (UKIRT) in Hawaii. The Wide Field Camera (WFCAM), built at the UK Astronomy Technology Centre (UK ATC), Edinburgh, is the world's most powerful infrared survey camera. It will survey large regions of the sky at infrared wavelengths and is expected to discover both the nearest objects outside our Solar System and the farthest known objects in the Universe.
Spectrograph Team Awaits October Hubble Servicing Mission
A $70 million instrument designed by the University of Colorado at Boulder that will be inserted on the Hubble Space Telescope during an October 2008 servicing mission should help astronomers better understand how galaxies, stars and planets evolved.

Hidden Population of Powerful Black Holes Revealed in Large Sky Survey

Related stories:

News discussion: