Cosmological Evolution of Fermi Large Area Telescope Gamma-Ray Blazars Using Novel Nonparametric Methods
Houdun Zeng, Vahé Petrosian, Tingfeng Yi
Abstract
Abstract Multiwavelength analyses of spectra of active galactic nuclei provide useful information on the physical processes in the accretion disk and jets of black holes. This, however, is limited to bright sources and may not represent the population as a whole. Another approach is through the investigation of the cosmological evolution of the luminosity function (LF), which shows varied evolution (luminosity and density) at different wavelengths. These differences and the correlations between luminosities can shed light on the jet-accretion disk connection. Most such studies use forward fitting parametric methods that involve several functions and many parameters. We use nonparametric, nonbinning methods developed by Efron & Petrosian and Lynden-Bell, for obtaining unbiased description of the evolution of the LF, from data truncated by observational selection effects. We present an analysis of the evolution of gamma-ray LF of blazars with a main focus on flat-spectrum radio quasars. This requires analysis of both gamma-ray and optical data, essential for redshift measurements, and a description of the joint LF. We use a new approach that divides the sample into two subsamples, each with its own flux limit. We use the Fermi Large Area Telescope and GAIA observations, and present results on the gamma-ray LF and its evolution, and determine the intrinsic correlation between the gamma-ray and optical luminosities corrected for the well-known false correlation induced by their similar redshift dependence and evolution of the two luminosities. We also present a direct estimation of the contribution of blazars to the spectrum of the extragalactic gamma-ray background.