Impacts of satellite galaxies on redshift-space distortion analysis

by Chiaki Hikage (University of Nagoya)

Thursday 9 Oct 2014, 15:00 → 16:00 US/Eastern

Universe

Redshift-space distortion due to the coherent bulk motion offers an important probe of cosmic growth rate and a method of testing gravity. The major uncertainty in this analysis comes from the nonlinear redshift-space distortion due to the random motion of galaxies inside their host halos, i.e., Fingers-of-God effect. We propose a novel method to eliminate the uncertainty using high-l multipole power spectra of galaxies such as hexadecapole component (l=4), which are mainly generated from the Fingers-of-God effect. Using luminous red galaxies (LRGs) samples of the Sloan Digital Sky Survey (SDSS), we have clearly detected the non-zero signature of the high-l multipole spectra, while the signature disappears in the power spectrum with the sample of the brightest LRGs only. In halo model picture, the high-l multipole spectra are dominated by the one-halo term of central-satellite pair contribution and then are sensitive to the satellite fraction and the satellite velocity dispersion. We show that the small-scale information of such high-l multipole spectrum substantially improve the measurement of the cosmic growth rate and also the satellite velocity dispersion.