2005/11/30 by Jaiyul Yoo, Jeremy L. Tinker, David H. Weinberg +3 · 1 citation
Environmental Science · Physics and Astronomy · #Galaxies: Formation, Evolution, Phenomena #Impact of Light on Environment and Health #Remote Sensing in Agriculture #astro-ph
paper · pdf · doi:10.1086/507591
published as Astrophys.J.652:26-42,2006 · 18 pages, 10 figures, accepted for publication in The Astrophysical Journal
arxiv created 2006/07/11 · openalex publication_date 2006/11/16 · arxiv updated 2009/12/01 · openalex created_date 2020/11/23 · openalex updated_date 2026/07/28
Galaxy-galaxy lensing measures the mean excess surface density DS(r) around a sample of lensing galaxies. We develop a method for combining DS(r) with the galaxy correlation function xigg(r) to constrain Omegam and sigma8, going beyond the linear bias model to reach the level of accuracy demanded by current and future measurements. We adopt the halo occupation distribution (HOD) framework, and we test its applicability to this problem by examining the effects of replacing satellite galaxies in the halos of an SPH simulation with randomly selected dark matter particles from the same halos. The difference between dark matter and satellite galaxy radial profiles has a ~10% effect on DS(r) at r<1 Mpc/h. However, if radial profiles are matched, the remaining impact of individual subhalos around satellite galaxies and environmental dependence of the HOD at fixed halo mass is <5% in DS(r) for 0.1<r<15 Mpc/h. We develop an analytic approximation for DS(r) that incorporates halo exclusion and scale-dependent halo bias, and we demonstrate its accuracy with tests against a suite of populated N-body simulations. We use the analytic model to investigate the dependence of DS(r) and the galaxy-matter correlation function xigm(r) on Omegam and sigma8, once HOD parameters for a given cosmological model are pinned down by matching xigg(r). The linear bias prediction is accurate for r>2 Mpc/h, but it fails at the 30-50% level on smaller scales. The scaling of DS(r) ~ Omegama(r) sigma8b(r) approaches the linear bias expectation a=b=1 at r>10 Mpc/h, but a(r) and b(r) vary from 0.8 to 1.6 at smaller r. We calculate a fiducial DS(r) and scaling indices a(r) and b(r) for two SDSS galaxy samples; galaxy-galaxy lensing measurements for these samples can be combined with our predictions to constrain Omegam and sigma8.