Johannes Buchner

Obscuration-dependent Evolution of Active Galactic Nuclei

We aim to constrain the evolution of AGN as a function of obscuration using an X-ray selected sample of

The Sloan Digital Sky Survey Quasar Catalog: Twelfth data release

sim2000

CANDELS/GOODS-S, CDFS, and ECDFS: photometric redshifts for normal and x-ray-detected galaxies

AGN from a multi-tiered survey including the CDFS, AEGIS-XD, COSMOS and XMM-XXL fields. The spectra of individual X-ray sources are analysed using a Bayesian methodology with a physically realistic model to infer the posterior distribution of the hydrogen column density and intrinsic X-ray luminosity. We develop a novel non-parametric method which allows us to robustly infer the distribution of the AGN population in X-ray luminosity, redshift and obscuring column density, relying only on minimal smoothness assumptions. Our analysis properly incorporates uncertainties from low count spectra, photometric redshift measurements, association incompleteness and the limited sample size. We find that obscured AGN with

The X-ray luminosity function of active galactic nuclei in the redshift interval z=3-5

N_{H}>{rm 10^{22}, cm^{-2}}

A spectroscopic survey of X-ray-selected AGNs in the northern XMM-XXL field

account for

X-ray spectral properties of the AGN sample in the northern XMM-XXL field

{77}^{+4}_{-5}%

Galaxy gas as obscurer – II. Separating the galaxy-scale and nuclear obscurers of active galactic nuclei

of the number density and luminosity density of the accretion SMBH population with

Galaxy gas as obscurer – I. GRBs x-ray galaxies and find an

L_{{rm X}}>10^{43}text{ erg/s}

N_{{\rm H}}^{3}\propto M_{\star }

, averaged over cosmic time. Compton-thick AGN account for approximately half the number and luminosity density of the obscured population, and

relation

{38}^{+8}_{-7}%