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Hard X-ray census of nearby active galaxies and implications for the cosmic history of black hole growth

Subject Area Astrophysics and Astronomy
Term from 2005 to 2011
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 5448593
 
Final Report Year 2012

Final Report Abstract

According to recent observations, supermassive black holes (SMBHs) have dramatically evolved over cosmic time and affected the formation and evolution of galaxies. Despite the success of deep X-ray surveys in providing us rich observational material on active galactic nuclei (AGN) at high redshifts, the AGN census at low redshifts remained limited until recently. Therefore, six years ago we proposed for the DFG Priority Programme 1177 to fill this gap in the history of SMBH growth with the help of an all-sky hard X-ray survey performed by the INTEGRAL observatory. Using this survey, we have measured the hard X-ray luminosity function and absorption column density distribution of local AGN. We have also tentatively detected a high-energy rollover in the cumulative hard X-ray spectrum of local AGN, which provides strong support to the popular hypothesis that the cosmic X-ray background is an integral record of SMBH growth. We determined the total energy release by AGN and therefore the total growth rate of SMBHs in the local Universe which is important “redshift-zero” point in the history of SMBH growth.

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