Clustering at 74 MHz

Abstract

In order to construct accurate point sources simulations at the frequencies relevant to 21-cm experiments, the angular correlation of radio sources must be taken into account. Using the 74 MHz VLA Low-Frequency Sky Survey, we measured the angular two-point correlation function, w(θ). We obtain the first measurement of clustering at the low frequencies relevant to 21-cm tomography. We find that a single power law with shape w(θ) = Aθ-γ fits well the data. For a 10° galactic cut, with all data at declinations δ < -10° also discarded, and a flux limit of S = 770 mJy, we obtain a slope of γ = (-1.21 ± 0.35). This value of γ is consistent with that measured from other radio catalogues at the metre wavelengths. The amplitude of clustering has a length of 2-. 6, and it is independent of the flux-density threshold. Journal compilation © 2010 RAS. No claim to original US government works.