Obscuration of quasars by dust in damped Lyman-alpha systems

Abstract

We present a largely analytical method to compute the obscuration of quasars by dust in damped Lyα absorption systems. The inputs required by our method are the observed luminosity function of quasars and the typical dust-to-gas ratio and empirical distribution of H I column densities in the damped Lyα systems. We use the dust-to-gas ratio inferred from the reddening of background quasars in our previous studies. As outputs, we obtain self-consistent corrections for the effects of obscuration on the luminosity function of quasars and the distribution of H I column densities in the damped Lyα systems