More Than 1,000 Massive Black Holes

Astronomers have managed to get a picture of more than a thousand supermassive black holes, a complex image of a crucial time when these monster space objects are growing, and offers clues about the environments in which they occur.

This achievement was made employing NASA's Chandra X-ray Observatory, the Spitzer Space Telescope and ground-based optical telescopes.

These black holes, located in the galaxies' centers, are hundreds of millions to several billion times larger than the sun and are named active galactic nuclei, or AGN.

The matter captured by these black holes starts spinning at high speeds, emitting high levels of light and other waves that can be detected. "We're trying to get a complete census across the universe of black holes and their habits," said Ryan Hickox of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Massachusetts.

The research team scanned a much bigger sky zone with shorter exposures, instead of insisting on analyzing small sky zones for longer time periods.

As the massive black holes power the brightest AGN emissions, they can be detected at vast distances, even with short exposures. "With this approach, we found well over a thousand of these monsters, and have started using them to test our understanding of these powerful objects," said co-investigator Christine Jones, also of the CfA.

The new research did not find any sign of gas torus (doughnut-shaped region) around supermassive black holes. "We found nearly all of the black holes are either naked or covered by a dense veil of gas," said Hickox. "Very few are in between, which makes us question how well we know the environment around these black holes."

This research discovered more than 600 obscured and 700 unobscured AGN, situated at 6-11 billion light years from Earth.

AGN were differentiated from stars and galaxies by examining the infrared colors of objects with Spitzer; after that, Chandra observations were employed, checking if these objects are AGN, a method especially efficient in discovering obscured AGN. "These results are very exciting, using two NASA Great Observatories to find and understand the largest sample of supermassive black holes ever found in the distant universe", said co-investigator Daniel Stern, of NASA's Jet Propulsion Laboratory in Pasadena, California.