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Author: Johannes Buchner Homepage: http://astrost.at/istics/ Further information: Growth of super-massive black holes over cosmic timeAbstract: Virtually all X-rays observed in deep fields originate close to growing supermassive black holes. X-rays indeed provide a clean and efficient selection of both unobscured and obscured AGN (active galactic nuclei). Recent work with deeper observations and improved analysis methodology allowed us to extend constraints on highly obscured, Compton-thick growth, thought to occur e.g. as a phase in mergers. We put constraints on the mass locked into black holes over cosmic time, an important constraint for cosmological simulations and our understanding of the co-evolution with galaxies. Further study of the obscurer of AGN reveals a complex behaviour with luminosity and redshift, which rules out entire sets of obscurer models. A new paradigm is proposed, the radiation-lifted torus model, in which the obscurer is Eddington-rate dependent and radiation pressure from the accretion process creates and displaces torus clouds. We place observational limits on the behaviour of this mechanism. 
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