Mark Lacy (NRAO)

Mid-infared AGN and the true nature of the quasar population -- Mark Lacy Colloquium

Abstract

I describe the results of a survey for AGN and quasars selected on the basis of mid-infrared colours. This survey is able to find both obscured and unobscured objects, approximately matched in mid-infrared luminosity over a wide range in luminosity from Seyferts to the most luminous quasars, and with redshifts up to 4.3. The survey consists of 672 objects with classifications and spectroscopic redshifts. I discuss the demographics of the AGN and quasar population revealed by this study, showing that the obscured quasar population continues to comprise at least 50% of the quasar population even at the highest quasar luminosities and redshifts. I will also discuss the radio, far-infrared, emission line and X-ray properties of the AGN and the insights they can give us into the nature of the obscured quasar population. Finally, I will describe how we might start to search for the massive, high redshift galaxies that might correspond to the hosts of these objects in a quiescent phase using the SERVS near-infrared survey with warm Spitzer.