Variance and skewness in the FIRST survey |
| |
| Authors: | M Magliocchetti S J Maddox O Lahav & J V Wall |
| |
| Institution: | Institute of Astronomy, Madingley Road, Cambridge CB3 0HA,;Royal Greenwich Observatory, Madingley Road, Cambridge CB3 0EZ |
| |
| Abstract: | We investigate the large-scale clustering of radio sources in the FIRST 1.4-GHz survey by analysing the distribution function ( counts in cells ). We select a reliable sample from the the FIRST catalogue, paying particular attention to the problem of how to define single radio sources from the multiple components listed. We also consider the incompleteness of the catalogue. We estimate the angular two-point correlation function w (θ), the variance Ψ2 and skewness Ψ3 of the distribution for the various subsamples chosen on different criteria. Both w (θ) and Ψ2 show power-law behaviour with an amplitude corresponding to a spatial correlation length of r 0 ～ 10 h ?1Mpc. We detect significant skewness in the distribution, the first such detection in radio surveys. This skewness is found to be related to the variance through Ψ3 = S 3(Ψ2)α, with α = 1.9 ± 0.1, consistent with the non-linear gravitational growth of perturbations from primordial Gaussian initial conditions. We show that the amplitude of variance and the skewness are consistent with realistic models of galaxy clustering. |
| |
| Keywords: | surveys galaxies: active galaxies: statistics large-scale structure of Universe |
|
|
