Low Frequency Radio Surveys: Searching for Cluster Halos and Relics

Recent advances in low frequency radio (ν < 0.5 GHz) instruments and techniques have made possible deep, high resolution surveys. Such surveys are ideal for finding the diffuse, steep-spectrum radio emission coming from halos and relics known to exist preferentially in clusters of galaxies which are undergoing major mergers. Here we describe two major surveys currently underway, which have the potential for discovering many such halo/relic systems. The first is the XMM-Newton Large Scale Structure project (XMM-LSS) in which a 8times8 square degree region will be mapped by XMM-Newton. The XMM-LSS project includes a low-frequency radio survey at both 325 and 74 MHz in order to compare the location of radio sources and the large scale structure. The second survey we describe is the VLA Low-frequency Sky Survey (VLSS) which is a NRAO-NRL collaboration to map the entire northern sky at 74 MHz. We describe both surveys, their current progress and identification of halo/relic candidates from the data acquired so far.