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The AGN Content of Hard X-ray Surveys

Published online by Cambridge University Press:  12 April 2016

Andrea Comastri ,
Cristian Vignali  and
Marcella Brusa
Andrea Comastri
Affiliation:
Osservatorio Astronomico di Bologna, via Ranzani 1, I40127 Bologna, Italy
Cristian Vignali
Affiliation:
Dept. of Astronomy and Astrophysics, Penn State University, 525 Davey Lab - University Park, PA 16802, USA
Marcella Brusa
Affiliation:
Dipartimento di Astronomia, Universita’ di Bologna, via Ranzani 1-40127 Bologna, Italy

Abstract

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Multiwavelength observations of the hard X-ray selected sources discovered by BeppoSAX, Chandra and XMM-Newton surveys have significantly improved our knowledge of the AGN population. The increasing number of X-ray obscured AGN so far discovered confirms the prediction of those AGN synthesis models for the X-ray background based on the Unified scheme. However, follow-up optical observations of hard X-ray selected sources indicate that their optical properties are quite varied and the simple relations between optical and X-ray absorption are by no means without exception. Moreover there is evidence of a substantial number of luminous X-ray sources hosted by apparently normal galaxies. In this paper the results obtained from multiwavelength observations of hard X-ray selected sources discovered by BeppoSAX and XMM-Newton are presented and briefly discussed.

Type
Part 3. X-ray Surveys for AGN
Information
International Astronomical Union Colloquium , Volume 184: AGN Surveys , 2002 , pp. 235 - 244
Copyright
Copyright © Astronomical Society of the Pacific 2002

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