Type:		Journal, Article
Title:		Quasars, Blazars, and the Gamma-Ray Sky
Author(s):		Impey, C.
Date:		1996/12
Abstract:		The statistical properties of gamma-ray emitting AGN are discussed, based on radio sources stronger than 1 Jy at 5 GHz that have been detected by the EGRET experiment on the Compton Gamma Ray Observatory. Most strong gamma-ray sources are radio quasars; radio galaxies are a small component of the population. Among the 1 Jy quasars, gamma-ray detections have stronger than average radio flux, but are not unusually compact or flat spectrum. The redshift distributions of gamma-ray detections and nondetections are indistinguishable. The energy budget of radio quasars detected by EGRET is dominated by gamma-rays. A model is constructed where radio and gamma-ray flux densities are weakly correlated, as observed, but with a large scatter much of which may be due to variability. Using this model to fit the EGRET detection rate in the 1 Jy sample, it is predicted that the gamma-ray detections arise from the high s_y_/S_r_ tail of the radio source population, and that many radio sources must emit gamma-ray fluxes not far below the EGRET sensitivity limit. Radio quasars contribute ~50% of the diffuse extragalactic background; optically selected QSOs must contribute 5% or less. Most of the flux and variance due to unresolved point sources is contributed by radio sources in the range 0.05 < S_rad_ < 0.5 Jy. The data are broadly consistent with Doppler-boosted emission from a relativistic jet at both gamma-ray and radio wavelengths.
Journal (full):		The Astronomical Journal
Volume:		112
Start Page:		2667
Link:		http://adsabs.harvard.edu/abs/1996AJ....112.2667I