Where are the supermassive black holes hiding?


Dust torus around a supermassive black hole
 
This artist's impression shows the thick dust torus that astronomers believe surrounds many supermassive black holes and their accretion discs. When the torus is seen edge-on as in this case, much of the light emitted by the accretion disc is blocked, creating a "hidden" black hole.

However, the sharp gamma-ray and X-ray eyes of Integral can peer through the thick dust and identify the black hole within. An Integral survey of the local universe found few hidden black holes, implying that they must have existed earlier (deeper) in the universe.

Hidden black holes in the local universe
 
This all-sky map shows regions of ionized hydrogen gas in the local universe. The hidden black holes detected in the INTEGRAL survey of high-energy X-ray sources are located within the diamond-shape marks. Many sources were detected through the line of sight of the dusty Milky Way galactic plane, which is the bright area stretching across the center of the entire image from left to right.



Release date: 18 January 2007