Optical CCD imaging of GHz-peaked-spectrum radio sources

Abstract

Twenty-eight GHz-peaked-spectrum (GPS) radio sources, mainly radio galaxies, have been imaged in the r and i optical bands in order to study the host galaxies and investigate the importance of galaxy-galaxy interactions in leading to the formation of this class of compact radio source. Here we present the observational results, while a subsequent paper will be devoted to the analysis and discussion. We find new identifications for seven objects previously classified as empty fields and one object misidentified with a Galactic star. This reduces the fraction of empty fields in the 1991 O'Dea, Baum, and Stanghellini sample to only ~8%. We find and confirm that disturbed optical morphologies are a common characteristic of GPS radio galaxies. Many of them also have close companions and appear to lie in groups or clusters of galaxies, and several appear to have very red r - i (or r - K) colors suggesting the presence of dust. Thus, our results suggest that galaxy-galaxy interactions and/or mergers play an important role in the GPS phenomenon.