Clustering and Light Profiles of Galaxies in the Environment of 20 Ultra-Steep-Spectrum Radio Sources

Abstract

We have analyzed galaxy properties in the neighborhood of 20 ultra–steep-spectrum (USS) radio sources taken from the Westerbork in the Southern Hemisphere (WISH) catalog of De Breuck and coworkers. Galaxies in these USS fields were identified in deep observations that were carried out in the K' band using the OSIRIS imager at the CTIO 4 m telescope. We find a statistically significant signal of clustering around our sample of USS sources. The angular extension of the detected USS source–galaxy clustering is θc ~ 20'', corresponding to a spatial scale of ~120 h-1 kpc, assuming the sources are at z ~ 1 in an Ωm = 0.3, ΩΛ = 0.7 model universe. These results are in agreement with those obtained by Best for radio galaxy–galaxy correlation, and Best and coworkers for radio-loud AGN–galaxy correlation. We have also analyzed the light distribution of the galaxies by fitting Sersic's law profiles. Our results show no significant dependence of the galaxy shape parameters on the projected distance to the USS source.