The Environments of a Complete Moderate-Redshift Sample of FIRST Bent-Double Radio Sources

Abstract

We present an optical spectroscopic and imaging study of the environments of a complete sample of moderate-redshift bent-double radio sources. More than half of the 40 radio galaxies in the sample are associated with clusters of Abell richness class 0 or greater at z<0.4. Most of the remaining objects are associated with groups, although a few appear to be hosted by nearly isolated elliptical galaxies. For the bent doubles appearing in poor environments, either dense gas must be associated with the systems to provide the ram pressure to bend the lobes or alternative bending mechanisms must be invoked to explain the radio morphologies. Correlation with the ROSAT All-Sky Survey bright and faint source catalogs reveals that the majority of the z<0.2 objects in our sample that we classify optically as clusters are also X-ray sources.