Statistics of Cosmological Black Hole Jet Sources: Blazar Predictions for theGamma-Ray Large Area Space Telescope

A study of the statistics of cosmological black-hole jet sources is appliedto EGRET blazar data, and predictions are made for GLAST. Black-hole jetsources are modeled as collimated relativistic plasma outflows with radiationbeamed along the jet axis due to strong Doppler boosting. The comoving ratedensity of blazar flares is assumed to follow a blazar formation rate (BFR),modeled by analytic functions based on astronomical observations and fits toEGRET data. The redshift and size distributions of gamma-ray blazars observedwith EGRET, separated into BL Lac object (BL) and flat spectrum radio quasar(FSRQ) distributions, are fit with monoparametric functions for thedistributions of the jet Lorentz factor \Gamma, comoving directional powerl'_e, and spectral slope. A BFR factor ~10 x greater at z ~ 1 than at presentis found to fit the FSRQ data. A smaller comoving rate density and greaterluminosity of BL flares at early times compared to the present epoch fits theBL data. Based on the EGRET observations, ~1000 blazars consisting of ~800FSRQs and FR2 radio galaxies and ~200 BL Lacs and FR1 radio galaxies will bedetected with GLAST during the first year of the mission. Additional AGNclasses, such as hard-spectrum BL Lacs that were mostly missed with EGRET,could add more GLAST sources. The FSRQ and BL contributions to the EGRETgamma-ray background at 1 GeV are estimated at the level of ~10 - 15% and ~2 -4%, respectively. EGRET and GLAST sensitivities to blazar flares are consideredin the optimal case, and a GLAST analysis method for blazar detection isoutlined.Comment: 17 pages, 9 figures, ApJ, in press, v.660, May 1, 2007 (minor changes from previous version