The combination of galaxy-galaxy lensing (GGL) with galaxy clustering is one of the most promising routes to determining the amplitude of matter clustering at low redshifts. We show that extending clustering+GGL analyses from the linear regime down to ∼0:5 h-1 Mpc scales increases their constraining power considerably, even after marginalizing over a exible model of non-linear galaxy bias. Using a grid of cosmological N-body simulations, we construct a Taylor-expansion emulator that predicts the galaxy autocorrelation Ξgg(r) and galaxy-matter cross-correlation Ξgm(r) as a function of σ8,Ωm, and halo occupation distribution (HOD) parameters, which are allowed to vary with large scale environment to represent possible effects of galaxy assembly bias. We present forecasts for a fiducial case that corresponds to BOSS LOWZ galaxy clustering and SDSS-depth weak lensing (effective source density ∼0:3 arcmin-2). Using tangential shear and projected correlation function measurements over 0:5 ≤ rp ≤ 30 h-1 Mpc yields a 1.8% constraint on the parameter combination σ80:58 Ωm , a factor of two better than a constraint that excludes non-linear scales (rp > 2 h-1 Mpc, 4 h-1 Mpc for t; wp). Much of this improvement comes from the non-linear clustering information, which breaks degeneracies among HOD parameters that would otherwise degrade the inference of matter clustering from GGL. Increasing the effective source density to 3 arcmin-2 sharpens the constraint on _80:58 m by a further factor of two. With robust modeling into the non-linear regime, low-redshift measurements of matter clustering at the 1-percent level with clustering+GGL alone are well within reach of current data sets such as those provided by the Dark Energy Survey.
|Original language||English (US)|
|State||Published - Sep 20 2017|
- Large scale structure
- Weak lensing
ASJC Scopus subject areas