Statistical determination of bulk flow motions
- Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth, PO1 3FX (United Kingdom)
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{sub 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{sub p} = 270{sup +433} km/s (also consistent with v{sub p} = 0) for this cluster sample (at z-bar = 0.1), which is in agreement with that predicted for a WMAP5-normalised ΛCDM model (i.e., v{sub p}(ΛCDM) = 203 km/s). This measurement does not lend support to recent claims of excessive bulk motions ( ≅ 1000 km/s) which appear in conflict with ΛCDM, although our large statistical error cannot rule them out. From the measured coherent evolution of v{sub p}, we develop a technique to re-construct the perturbed potential, as well as estimating the unbiased matter density fluctuations and scale-independent bias.
- OSTI ID:
- 22272959
- Journal Information:
- Journal of Cosmology and Astroparticle Physics, Vol. 2010, Issue 01; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1475-7516
- Country of Publication:
- United States
- Language:
- English
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