The X-ray Luminosity Function Evolution of Quasars and the Correlation Between the X-ray and Ultraviolet Luminosities

Abstract

We explore the evolution of the X-ray luminosity function of quasars and the intrinsic correlation between the X-ray and 2500\AA $\,$ ultraviolet luminosities, utilizing techniques verified in previous works and a sample of over 4000 quasars detected with Chandra and XMM-Newton in the range $0<z<5$. We find that quasars have undergone significantly less evolution with redshift in their total X-ray luminosity than in other wavebands. We then determine that the best fit intrinsic power law correlation between the X-ray and ultraviolet luminosities, of the form $L'_{\rm X} \propto ({L'_{\rm UV}})^{\gamma}$, is $\gamma=0.28\pm$0.03, and we derive the luminosity function and density evolution in the X-ray band. We discuss the implications of these results for models of quasar systems.