Fermi Gamma-ray Space Telescope

Blazar Demographics Using Fermi+Multiwavelength Data

P. Mao
C. M. Urry, F. Massaro

Abstract:

Blazars are the perfect laboratories to study relativistic jets of AGN and therefore are crucial to our understanding of large scale structures in the universe. We combined multi-wavelength data for blazars from the Roma-BZCAT catalog and present the fluxes and Spectral Energy Distributions (SEDs), for a sample of 2214 blazars, in which gamma ray data from Fermi were available for orders of magnitude more objects compared with previous studies. We confirmed the anti-correlation between radio luminosity and synchrotron peak frequency, although with greater scatter than was seen in the smaller sample in previous studies. An empirical SED model was determined from all available blazar data and depending only on the radio luminosity at 1.4~GHz and the redshift. Statistical analyses were carried out against BL Lacs without redshifts to investigate the potential biases in our estimator, as these sources were excluded due to lack of luminosities. These blazars, though showing slightly different distributions from our sample, could not be high luminosity, high synchrotron peaked objects and therefore would not disprove the 'blazar sequence'. We then performed a Monte-Carlo simulation of the blazar demographics utilizing the estimator, and compared simulated surveys with actual observations. The simulated surveys show similar redshift, flux and luminosities distributions, and also recover apparent evolutions observed.