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What can be learnt from extragalactic X‐ray surveys?
Author(s) -
Fabian A.C.
Publication year - 2003
Publication title -
astronomische nachrichten
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.394
H-Index - 63
eISSN - 1521-3994
pISSN - 0004-6337
DOI - 10.1002/asna.200310002
Subject(s) - physics , astrophysics , active galactic nucleus , galaxy , x ray background , metallicity , astronomy , radiative transfer , black hole (networking) , computer network , routing protocol , routing (electronic design automation) , quantum mechanics , computer science , link state routing protocol
Abstract Extragalactic X‐ray surveys reveal many Active Galactic Nuclei (AGN) as well as clusters and groups of galaxies. Many of the AGN are obscured, leading to the hard spectrum of the X‐ray Background. Constraints from the absorptioncorrected X‐ray Background spectrum and the local mass density of black holes on the radiative efficiency and growth of accreting black holes are discussed. The use of clusters for the determination of cosmological parameters, and the energy and metallicity loss by galaxies and AGN, is noted.