2015/06/30 by Teppei Okumura, Nick Hand, U. Seljak +3 · 2 citations
Physics and Astronomy · #Astronomy #Astrophysics #Cosmology and Gravitation Theories #Galactic halo #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy formation and evolution #Halo #Physics #Redshift #Satellite galaxy #Stellar, planetary, and galactic studies #astro-ph.CO
paper · pdf · doi:10.1103/physrevd.92.103516
published as Phys. Rev. D 92, 103516 (2015) · 16 pages, 9 figures, 1 table, minor changes made with respect to published version
openalex publication_date 2015/11/19 · arxiv created 2015/11/25 · arxiv updated 2015/11/26 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
Theoretical modeling of the redshift-space power spectrum of galaxies is crucially important to correctly extract cosmological information from galaxy redshift surveys. The task is complicated by the nonlinear biasing and redshift space distortion (RSD) effects, which change with halo mass, and by the wide distribution of halo masses and their occupations by galaxies. One of the main modeling challenges is the existence of satellite galaxies that have both radial distribution inside the halos and large virial velocities inside halos, a phenomenon known as the Finger-of-God (FoG) effect. We present a model for the redshift-space power spectrum of galaxies in which we decompose a given galaxy sample into central and satellite galaxies and relate different contributions to the power spectrum to 1-halo and 2-halo terms in a halo model. Our primary goal is to ensure that any parameters that we introduce have physically meaningful values, and are not just fitting parameters. For the lowest order 2-halo terms we use the previously developed RSD modeling of halos in the context of distribution function and perturbation theory approach. This term needs to be multiplied by the effect of radial distances and velocities of satellites inside the halo. To this one needs to add the 1-halo terms, which are nonperturbative. We show that the real space 1-halo terms can be modeled as almost constant, with the finite extent of the satellites inside the halo inducing a small k2R2 term over the range of scales of interest, where R is related to the size of the halo given by its halo mass. We adopt a similar model for FoG in redshift space, ensuring that FoG velocity dispersion is related to the halo mass. For FoG k2 type expansions do not work over the range of scales of interest and FoG resummation must be used instead. We test several simple damping functions to model the velocity dispersion FoG effect. Applying the formalism to mock galaxies modeled after the ``CMASS'' sample of the BOSS survey, we find that our predictions for the redshift-space power spectra are accurate up to k\ensuremath≃0.4 h Mpc^\ensuremath-1 within 1% if the halo power spectrum is measured using N-body simulations and within 3% if it is modeled using perturbation theory.