Measurement of the angular correlation function of radio galaxies from the NRAO VLA Sky Survey

We quantify the angular distribution of radio sources in the NRAO VLA Sky Survey (NVSS) by measuring the two-point angular correlation function Ω(θ). By careful consideration of the resolution of radio galaxies into multiple components, we are able to determine both the galaxy angular clustering and the size distribution of giant radio galaxies. The slope of the correlation function for radio galaxies agrees with that for other classes of galaxy, γ = 1.8, with a 3D correlation lenght r₀ ~ 6 h^-1 Mpc (under certain assumptions). Calibration problems in the survey prevent clustering analysis below S_{1.4 GHz} = 10 mJy. About 7 per cent of radio galaxies are resolved by NVSS into multiple components, with a power-law size distribution. Our work calls into question previous analyses and interpretations of Ω(θ) from radio surveys.