Environmental clustering properties of high-energy blazars

The intrinsic properties of the host galaxies of blazars are often unable to be measured due to the high brightness and relativistic beaming of the jet itself. This makes it difficult to determine, for example, whether there is a difference in the parent populations of BL Lacs versus those of flat-spectrum radio quasars (FSRQs). As an alternative to direct observation of the host galaxy, we study the Mpc-scale environments using data from the Sloan Digital Sky Survey. Our study of 757 blazars at 0.05<z<0.75 shows a significant increase in local density over field galaxies. There is no measurable difference, however, between the clustering amplitude of BL Lacs and FSRQs. Similar clustering amplitudes are found for a large sample of powerful radio galaxies. As a result, this data does not rule out a unification model in which BL Lacs and FSRQs are beamed versions of FRI and FRII radio galaxies, respectively. Within the context of the blazar sequence/envelopemodel, our results suggest that the radiative efficiency of accretion, on which the observed properties of jet emission depend, is not affected by the local galactic environment.