The effect of partial obscuration on the luminosity dependence of the obscured fraction in active galactic nuclei

Abstract

Surveys of active galactic nuclei (AGN) in different observational regimes seem to give different answers for the behaviour of the obscured fraction with luminosity. Based on the complex spectra seen in recent studies, we note that partial covering could significantly change the apparent luminosities of many AGN, even after apparent X-ray absorption correction. We explore whether this effect could reproduce the observed dependence of the obscured fraction on the apparent X-ray luminosities seen between 2 and 10 keV. We can reproduce the observed trend in a model where 33 per cent of AGN are unobscured, 30 per cent are heavily buried and 37 per cent have a range of intermediate partial coverings. Our model is also tentatively successful at reproducing observed trends in the X-ray versus infrared luminosity ratio for AGN. ©2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.