Open AccessVariance and skewness in the FIRST survey
Author(s) -
Magliocchetti M.,
Maddox S. J.,
Lahav O.,
Wall J. V.
Publication year - 1998
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.1998.01904.x
Subject(s) - skewness , physics , amplitude , variance (accounting) , gaussian , cluster analysis , statistics , statistical physics , kurtosis , power law , astrophysics , correlation function (quantum field theory) , distribution (mathematics) , econometrics , mathematics , mathematical analysis , optics , quantum mechanics , accounting , business , dielectric
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 Ψ 2 and skewness Ψ 3 of the distribution for the various subsamples chosen on different criteria. Both w (θ) and Ψ 2 show power‐law behaviour with an amplitude corresponding to a spatial correlation length of r 0 ∼ 10 h −1 Mpc. 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 Ψ 3 = S 3 (Ψ 2 ) 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.