B_gg revisited: The environments of low-excitation radio galaxies and unified models

Abstract

Recent measurements of the galaxy clustering environments around intermediate-redshift radio sources have suggested a systematic environmental difference between radio galaxies and radio-loud quasars, in contradiction to the predictions of simple unified models for the two classes of object. I show that the apparent difference arises mainly as a result of the properties of low-excitation radio galaxies included in the radio-galaxy sample, which tend to lie in significantly richer environments. The environmental properties of high-excitation radio galaxies and quasars are statistically consistent in the redshift range 0.15 < z <0.4, as unified models would predict.