Molonglo reference catalog 1 Jy radio source survey. II : radio structures of galaxy identifications

Abstract

This is the second in a series of papers discussing the radio, optical, and near-IR properties of a large and complete sample of radio sources selected from the Molonglo Reference Catalog (MRC) at 408 MHz. The sample consists of 557 radio sources from the MRC that have S_0.408 >= 0.95 Jy, -30 deg < delta < -20 deg, and |b| >= 20 deg but excluding the right ascension range of 14^h03^m-20^h20^m. While 111 of these are identified with quasars (including six with BL Lac objects), a vast majority of the rest are identified with galaxies. Only a small fraction (<~2%) appear to have no optical or near-IR counterparts down to an r magnitude of ~24 or a K magnitude of ~19. A similar fraction have ambiguous identifications. This paper presents the radio structures of the 446 radio sources in the sample that are either identified with galaxies or that have remained unidentified. Most of the structural information given in the paper is based on high-resolution (~1"-10") observations made with the Very Large Array at a frequency of 4.86 GHz. Several of the large or diffuse sources were also observed at 1.41 GHz. Contour plots of the radio images are also presented for the well-resolved sources. A substantial fraction (~20%) of the sources in the galaxy sample is found to be of the ``compact steep spectrum'' variety with alpha^4.86_0.408>0.5 and linear size l <~ 20 kpc (for H_0 = 50 km s^-1 Mpc^-1 q_0 = 0.5).