Emulating galaxy clustering and galaxy–galaxy lensing into the deeply non-linear regime: methodology, information, and forecasts

Journal Article · Sat Aug 25 00:00:00 EDT 2018 · Monthly Notices of the Royal Astronomical Society

DOI:https://doi.org/10.1093/mnras/sty2258· OSTI ID:1610360

Wibking, Benjamin D.  ^[1]; Salcedo, Andrés N. ^[1]; Weinberg, David H. ^[1]; Garrison, Lehman H. ^[2]; Ferrer, Douglas ^[2]; Tinker, Jeremy ^[3]; Eisenstein, Daniel ^[2]; Metchnik, Marc ^[4]; Pinto, Philip ^[4]

---

1. The Ohio State Univ., Columbus, OH (United States)
2. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States)
3. New York Univ., NY (United States)
4. Univ. of Arizona, Tucson, AZ (United States)

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. Here, we show that extending clustering+GGL analyses from the linear regime down to |$${\sim } 0.5 \, h^{-1}$$| Mpc scales increases their constraining power considerably, even after marginalizing over a flexible 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 ξ_gg(r) and galaxy-matter cross-correlation ξ_gm(r) as a function of σ₈, Ω_m, 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 |$$0.5 \le r_\mathrm{ p} \le 30 \, h^{-1}$$| Mpc yields a 2 per cent constraint on the parameter combination |$$\sigma _8\Omega _\mathrm{ m}^{0.6}$$|, a factor of two better than a constraint that excludes non-linear scales (|$$r_\mathrm{ p} \gt 2 \, h^{-1}$$| Mpc, |$$4 \, h^{-1}$$| Mpc for γ_t, |$$w$$|_p). Much of this improvement comes from the non-linear clustering information, which breaks degeneracies among HOD parameters. Increasing the effective source density to 3 arcmin^-2 sharpens the constraint on |$$\sigma _8\Omega _\mathrm{ m}^{0.6}$$| by a further factor of two. With robust modelling into the non-linear regime, low-redshift measurements of matter clustering at the 1-per cent level with clustering+GGL alone are well within reach of current data sets such as those provided by the Dark Energy Survey.

• Research Organization: Krell Institute, Ames, IA (United States); Harvard Univ., Cambridge, MA (United States)
• Sponsoring Organization: USDOE Office of Science (SC); USDOE National Nuclear Security Administration (NNSA); National Science Foundation (NSF)
• Grant/Contract Number: FG02-97ER25308; SC0013718; DGE-1343012; AST-1516997; AST-1313285; 1228509
• OSTI ID: 1610360
• Journal Information: Monthly Notices of the Royal Astronomical Society, Vol. 484, Issue 1; ISSN 0035-8711
• Publisher: Royal Astronomical Society
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
astronomy & astrophysics
gravitational lensing
cosmological parameters
arge-scale structure of the Universe