Galaxy Clustering in the Mira-Titan Universe. I. Emulators for the Redshift Space Galaxy Correlation Function and Galaxy–Galaxy Lensing

Abstract

We construct accurate emulators for the projected and redshift space galaxy correlation functions and excess surface density as measured by galaxy–galaxy lensing, based on halo occupation distribution modeling. Using the complete Mira-Titan suite of 111 N-body simulations, our emulators vary over eight cosmological parameters and include the effects of neutrino mass and dynamical dark energy. We demonstrate that our emulators are sufficiently accurate for the analysis of the Baryon Oscillation Spectroscopic Survey DR12 CMASS galaxy sample over the range 0.5 ≤ r ≤ 50 h −1 Mpc. Furthermore, we show that our emulators are capable of recovering unbiased cosmological constraints from realistic mock catalogs over the same range. Our mock catalog tests show the efficacy of combining small-scale galaxy–galaxy lensing with redshift space clustering and that we can constrain the growth rate and σ 8 to 7% and 4.5%, respectively, for a CMASS-like sample using only the measurements covered by our emulator. With the inclusion of a cosmic microwave background prior on H 0, this reduces to a 2% measurement of the growth rate.

Emulating Power Spectra for Prereconstructed and Postreconstructed Galaxy Samples

“…However, it is much more challenging to build PT-based models that can work on the same scales for P post or P cross due to complexities brought in by the reconstruction process . One alternative to building PT-based models is to develop simulation-based models, i.e., the emulators, which have been extensively studied and developed for statistics for the prereconstructed density fields (Wibking et al 2019;Winther et al 2019;Zhai et al 2019;Kobayashi et al 2020;Donald-McCann et al 2022;Yuan et al 2022;Cuesta-Lazaro et al 2023a, 2023bKwan et al 2023).…”