Impacts of satellite galaxies on redshift-space distortion analysis
by
Chiaki Hikage(University of Nagoya)
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Universe
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Description
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.