Clustering of Extragalactic Sources from 151 MHz to 232 MHz: Implications for Cosmological 21-cm Observations

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. This paper presents a measurement of angular two-point correlation function, w(θ), at 232 MHz from the MIYUN survey - tentative measurements of w(θ) are also performed at 151 MHz. It is found that double power law with shape w(θ) = A θ^{-γ} fits the 232 MHz data well. For the angular lenght of 0.2 degrees < θ< 0.6 degrees, γ~ -1.12, and this value of slope is independent of the flux-density threshold; while for angular lenghts much greater than 0.6 degrees, γhas a shallower value of about -0.16. By comparing the results of this paper with previous measurements of w(θ), it is discussed how w(θ) changes with the change of frequency and completness limit.

5 pages, 4 figures, 1 table.