Faint 1.4 GHz sources in the 2dF Galaxy Redshift Survey

Abstract

The Australia Telescope Compact Array (ATCA) has been used to survey at 1.4GHz, a small region (< 3 sq deg) overlapping with the 2dF Galaxy Redshift Survey (Colless et al. 2001, MNRAS, 328, 1039). We surveyed with a varying radio sensitivity, ranging from 1mJy - 20microJy (1 sigma). There are 365 2dFGRS sources with z > 0.001 lying within the surveyed region, of which 316 have reliable spectral classification. Following Sadler et al. 2002 (MNRAS, 329, 227), we visually classified 176 as AGN or early-type galaxies, and 140 as star-forming galaxies. We derived radio flux density measurement or upperlimits for each of the 365 2dFGRS sources. The fraction of radio detected 2dFGRS star-forming galaxies increases from ~ 50% at ~ 0.7mJy up to ~ 60% at ~ 0.2mJy. The mean redshift for the fraction of radio detected star-forming galaxies increases with increasing radio detection sensitivity, while the mean redshift is fairly constant for the AGN/early-type fraction. We found very similar radio detection rates of 2dFGRS galaxies for both the AGN/early-type and star-forming components. The radio detection rate increases approximately linearly with respect to the rate of increase in radio detection sensitivity. We derived the radio luminosity function for our sample and it was found to be consistent with that of Sadler et al. 2002. We have also compared the total flux densities of NVSS sources common to our survey, and we discuss strategies for a large-scale radio survey of the 2dFGRS sample.