2007ApJS..170...71L

We present a statistical study of several fundamental properties of radio sources in nearby clusters (z≤0.2), including the radial distribution within clusters, the radio luminosity function (RLF), and the fraction of galaxies that is radio active (radio active fraction, RAF). The analysis is carried out for a sample of 573 clusters detected in the X-ray and also observed at 1.4 GHz in the NRAO VLA Sky Survey. The X-ray data are used to locate the cluster center and estimate cluster mass. In addition, near-IR data from the Two Micron All-Sky Survey are used to identify the brightest cluster galaxies (BCGs) and to construct the K-band luminosity function. Our main results include (1) The surface density profile of radio-loud active galactic nuclei (AGNs) is much more concentrated than that of all galaxies and can be described by the Navarro, Frenk, & White profile with concentration ∼25. More powerful radio sources are more concentrated than the weaker ones. (2) A comparison of the RLFs in the clusters and in the field shows that the cluster AGN number density is about 5700 times higher, corresponding to a factor of 6.8 higher probability of a galaxy being radio active in the cluster than in the field. We suggest that about 40%-50% of radio-loud AGNs in clusters may reside in low-mass galaxies (M_K≳-23); if an equivalent population exists in the field, the RLFs in the two environments can be brought into better agreement. The strongest support for the existence of this low-mass population comes from their spatial distribution and RLF. (3) The RAFs of cluster galaxies of different stellar mass are estimated directly. About 5% of galaxies more luminous than the characteristic luminosity (M_K≤M_K*~-24) host radio-loud AGNs. The RAF for BCGs is >30%, and depends on the cluster mass. Compared to the field population, cluster galaxies have 5-10 times higher RAF. Combining the AGN RLF and spatial distribution within clusters, we estimate that they may inject an energy of ∼0.13 keV per particle to the intracluster medium near the cluster center. We also investigate the degree of contamination by cluster radio sources on the yields of Sunyaev-Zel'dovich effect (SZE) cluster surveys. Under our simple model extrapolating to higher frequency, we estimate that as many as 10% of clusters detected at 150 GHz may host AGNs whose flux is comparable to the cluster SZE signal. The fraction is expected to be much higher at lower frequency.