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

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 forty radio galaxies in the sample are associated with Abell richness class 0 or greater clusters 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 will have to be invoked to explain the radio morphologies. Correlation with the ROSAT All Sky Survey Bright and Faint Source Catalogs reveals the majority of the z < 0.2 objects in our sample that we classify optically as clusters are also X-ray sources. Subject headings: galaxies:clusters:general — galaxies: elliptical and lenticular, cD — galaxies: intergalactic medium — radio continuum: galaxies — X-rays: galaxies