The Angular Two‐Point Correlation Function for the FIRST Radio Survey

Abstract

The FIRST (Faint Images of the Radio Sky at Twenty centimeters) survey now covers 1550 deg2 of sky, where 07h16 α 17h40 and 28°.3 δ 42°. This yields a catalog of 138,665 sources above the survey threshold of 1 mJy, about one-third of which are in double-lobed and multicomponent sources. We have used these data to obtain the first high-significance measurement of the two-point angular correlation for a deep radio sample. We find that the correlation function between 002 and 2° is well fitted by a power law of the form Aθγ, where A ≈ 3 × 10–3 and γ ≈ -1.1. On small scales (θ < 02), double and multicomponent sources are shown to have a larger clustering amplitude than that of the whole sample. Sources with flux densities below 2 mJy are found to have a shallower slope than that obtained for the whole sample, consistent with there being a significant contribution from starbursting galaxies at these faint fluxes. The cross-correlation of radio sources and Abell clusters is determined. A preliminary approach to inferring spatial information is outlined.