The evidence for obscured AGN and in particular for obscured quasars is discussed. The spectrum and source modelling of the X-ray Background suggests that most massive black holes grow by obscured accretion. A possible major growth phase which is Compton thick is explored and shown to be difficult to detect directly with current instruments.
@article{arxiv.astro-ph/0109156,
title = {Obscured Accretion and Black Holes},
author = {A. C Fabian},
journal= {arXiv preprint arXiv:astro-ph/0109156},
year = {2007}
}
Comments
8 pages, 6 figures, presented at the meeting: "Issues in unifications of AGNs" Marciana Marina, May 2001; eds. R. Maiolino, A. Marconi and N. Nagar