Contamination by Point Radio Sources

Kim Coble has been analyzing point radio sources in the data collected by the SZE group at BIMA (at 30 GHz frequency, where 1GHz = 1 GigaHertz), OVRO (30 GHz) and the VLA (5 GHz). There are about 75 cluster fields and 18 CMB (blank) fields in this data. These data have deep sensitivity and can be used to model point source contamination in simulations for the SZA and other experiments. Point sources can be an important foreground contaminant in Cosmic Microwave Background (CMB) and SZ experiments, so a detailed point source model will be of great use for the SZA.

In order to characterize the point sources, we're calculating source counts as a function of flux (dN/dS), as well as spectral indices and correlations between the 5 and 30 GHz data. Some of the data analysis issues include selection effects due to flux, noise level, source position and completeness.

Some of the questions we're investigating include:

• whether an overdensity of point sources in a survey implies a cluster
• how point sources in the blank and cluster fields compare
• whether or not source counts in regions more than 10 arcsec from a cluster center are like those in random fields

A preliminary comparision of cluster and random CMB (blank) fields indicate that sources are more abundant in the cluster fields, even in the outer regions of a cluster field. Hence this work forms an important component of the data analysis for the SZA.