# Galaxy Clustering in the Mira-Titan Universe I: Emulators for the redshift space galaxy correlation function and galaxy-galaxy lensing

## TL;DR

This paper develops accurate emulators for galaxy clustering and lensing measurements using HOD modeling across various cosmologies, enabling precise constraints on cosmological parameters from galaxy survey data.

## Contribution

The paper introduces emulators for galaxy correlation functions and lensing based on the Mira-Titan simulations, incorporating neutrino mass and dark energy effects, and demonstrates their accuracy and utility.

## Key findings

- Emulators accurately reproduce galaxy clustering and lensing measurements.
- Combining small-scale lensing with clustering constrains growth rate and c_8 to 4.5% and 7%.
- Including CMB priors improves growth rate measurement to 2%.

## 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 (HOD) 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 BOSS DR12 CMASS galaxy sample over the range 0.5 < r < 50 Mpc/h. 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 \sigma_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 CMB prior on H_0, this reduces to a 2% measurement on the growth rate.