Astronomy and Astrophysics – Astrophysics – Cosmology and Extragalactic Astrophysics
Scientific paper
2010-01-08
JCAP 1001:025,2010
Astronomy and Astrophysics
Astrophysics
Cosmology and Extragalactic Astrophysics
8 pages, 5 figures
Scientific paper
We present here a new parameterization for the bulk motions of galaxies and clusters (in the linear regime) that can be measured statistically from the shape and amplitude of the two-dimensional two-point correlation function. We further propose the one-dimensional velocity dispersion (v_p) of the bulk flow as a complementary measure of redshift-space distortions, which is model-independent and not dependent on the normalisation method. As a demonstration, we have applied our new methodology to the C4 cluster catalogue constructed from Data Release Three (DR3) of the Sloan Digital Sky Survey. We find v_p=270^{+433}km/s (also consistent with v_p=0) for this cluster sample (at z=0.1), which is in agreement with that predicted for a WMAP5-normalised LCDM model (i.e., v_p(LCDM=203km/s). This measurement does not lend support to recent claims of excessive bulk motions (\simeq1000 km/s) which appear in conflict with LCDM, although our large statistical error cannot rule them out. From the measured coherent evolution of v_p, we develop a technique to re-construct the perturbed potential, as well as estimating the unbiased matter density fluctuations and scale--independent bias.
Miller Christopher J.
Nichol Robert C.
Sabiu Cristiano G.
Song Yong-Seon
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