Statistics of Cosmological Black Hole Jet Sources: Blazar Predictions for GLAST

A study of the statistics of cosmological black-hole jet sources is applied to EGRET blazar data, and predictions are made for GLAST. Black-hole jet sources are modeled as collimated relativistic outflows with radiation beamed along the jet axis due to strong Doppler boosting. The comoving density dependence of the blazar formation rate (BFR) is assumed to follow the cosmic star formation history or cosmic evolution of IR-luminous galaxies. A parameter study of blazar redshift and size distributions is presented using synchrotron and external Compton (EC) beaming factors for different BFRs. The redshift and luminosity distributions of gammaray blazars observed with EGRET, separated into BL Lac object (BL) and flat spectrum radio quasar (FSRQ) distributions, are fit with monoparametric functions for the distributions of the jet Lorentz factor Γ, comoving directional power l′e, and spectral slope. The detection characteristics of a telescope are approximated by its νFν sensitivity threshold fǫ at photon frequency ν = mec ǫ/h. Values of Γ and l′e that fit the data for FSRQs and BLs are estimated. Based on the EGRET observations, predictions for the detectability of blazars with GLAST are made. GLAST would detect a much larger fraction of BLs in its sample than found with EGRET but that BL evolution must be negative in order that BLs not overproduce the γ-ray background. The FSRQ contribution to the EGRET extragalactic γ-ray background is estimated at the level of ≈ 30%. EGRET and GLAST sensitivities to blazar flares are considered in the optimal case, and a GLAST analysis method for blazar flares is outlined. Subject headings: AGNs: blazars—black holes—gamma-ray bursts