Simulations of Deep Pencil-Beam Redshift Surveys

• Published in: arXiv.org 2001-03
• Main Authors: Yoshida, N, Colberg, J, White, S D M, Evrard, A E, MacFarland, T J, Couchman, H M P, Jenkins, A, Frenk, C S, Pearce, F R, Efstathiou, G, Peacock, J A, Thomas, P A
• Format: Article
• Language: English
• Subjects: Clumps; Cold dark matter; Computer simulation; Cones; Cosmological constant; Dark matter; Galaxies; Histograms; Periodic variations; Red shift
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.0011212

We create mock pencil-beam redshift surveys from very large cosmological \(N\)-body simulations of two Cold Dark Matter cosmogonies, an Einstein-de Sitter model (\(\tau\)CDM) and a flat model with \(\Omega_0 =0.3\) and a cosmological constant (\(\Lambda\)CDM). We use these to assess the significance of the apparent periodicity discovered by Broadhurst et al. (1990). Simulation particles are tagged as `galaxies' so as to reproduce observed present-day correlations. They are then identified along the past light-cones of hypothetical observers to create mock catalogues with the geometry and the distance distribution of the Broadhurst et al. data. We produce 1936 (2625) quasi-independent catalogues from our \(\tau\)CDM (\(\Lambda\)CDM) simulation. A couple of large clumps in a catalogue can produce a high peak at low wavenumbers in the corresponding one-dimensional power spectrum, without any apparent large-scale periodicity in the original redshift histogram. Although the simulated redshift histograms frequently display regularly spaced clumps, the spacing of these clumps varies between catalogues and there is no `preferred' period over our many realisations. We find only a 0.72 (0.49) per cent chance that the highest peak in the power spectrum of a \(\tau\)CDM (\(\Lambda\)CDM) catalogue has a peak-to-noise ratio higher than that in the Broadhurst et al. data. None of the simulated catalogues with such high peaks shows coherently spaced clumps with a significance as high as that of the real data. We conclude that in CDM universes, the kind of regularity observed by Broadhurst et al. has a priori probability well below \(10^{-3}\).