Quasar Surveys and the VLT

Abstract

In the last decade a veritable explosion in the numbers of known quasars has occurred, and much has been learnt about the properties and evolution of the quasar population at radio, optical and X-ray wavelengths. Notwithstanding the increase in our knowledge, there remain significant portions of the luminosity-redshift plane, intrinsically faint quasars at intermediate redshifts z ~ 2–3 for example, where information remains limited or non-existent. Once suitable quasar samples have been defined the VLT, will be well-suited to the investigation of a number of these areas, while for others, such as luminous quasars at the highest redshifts, this is less true. Prospects for employing the VLT to study several outstanding questions relating to the evolution of the quasar population are discussed. Using quasars as probes of material lying along the line-of-sight will be a key area in the era of 8-metre telescopes. Likely progress towards defining quasar samples, suitable for investigations by the VLT of intervening hydrogen and metal absorption systems, is reviewed briefly.