Research Note

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

Department of Physics, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK

Corresponding author: m.hardcastle@bristol.ac.uk

Received: 31 October 2003
Accepted: 24 November 2003

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 , as unified models would predict.