INTEGRAL observations suggest unified model for Active Galactic Nuclei requires a rethink
Wednesday, August 3, 2011 - 12:30
in Astronomy & Space
Scrutinizing a large sample of Active Galactic Nuclei with INTEGRAL, astronomers have found that, unexpectedly, sources affected by stronger absorption at lower energies show an excess emission in the hard X-ray band when compared to their less obscured counterparts. The excess is likely due to reflection of X-rays off the same dense clouds responsible for absorption. Unaccounted for in the unified paradigm of Active Galactic Nuclei, the finding calls for a rethinking of some of this model's facets. The reflected radiation could also represent the long-sought missing part of the Cosmic X-ray Background.