Cosmological constraints from galaxy clustering and galaxy-galaxy lensing with extended SubHalo Abundance Matching

TL;DR

This paper demonstrates a novel joint analysis of galaxy clustering and galaxy-galaxy lensing using extended SubHalo Abundance Matching to constrain cosmological parameters, achieving results consistent with Planck and validating the method with simulations.

Contribution

It introduces the first cosmological constraints from combined galaxy clustering and lensing using extended SHAMe, and constrains all five SHAMe parameters.

Findings

Measured S_8 = 0.793^{+0.025}_{-0.024}, consistent with Planck.

Extended analysis to small scales improves constraints by 21%.

Validated methodology with TNG300 simulations, recovering input cosmology.

Abstract

We present the first cosmological constraints from a joint analysis of galaxy clustering and galaxy-galaxy lensing using extended SubHalo Abundance Matching (SHAMe). We analyse stellar mass-selected Galaxy And Mass Assembly (GAMA) galaxy clustering and Kilo-Degree Survey (KiDS-1000) galaxy-galaxy lensing and find constraints on $S_8\equiv\sigma_8\sqrt{\Omega_{\rm m}/0.3}=0.793^{+0.025}_{-0.024}$, in agreement with Planck at 1.7$\sigma$, with $\sigma_8$ the mass density fluctuation amplitude in 8 $h^{-1}{\rm Mpc}$ sphere at present and $\Omega_{\rm m}$ the density parameter in total matter. These results are in agreement with the Cosmic Microwave Background results from Planck. We are able to constrain all 5 SHAMe parameters, which describe the galaxy-subhalo connection. We validate our methodology by first applying it to simulated catalogues, generated from the TNG300 simulation, which mimic the stellar mass selection of our real data. We show that we are able to recover the input cosmology for both our fiducial and all-scale analyses. Our all-scale analysis extends to scales of galaxy-galaxy lensing below $r_\mathrm{p}<1.4\,\mathrm{Mpc}/h$, which we exclude in our fiducial analysis to avoid baryonic effects. When including all scales, we find a value of $S_8$, which is 1.26$\sigma$ higher than our fiducial result (against naive expectations where baryonic feedback should lead to small-scale power suppression), and in agreement with Planck at 0.9$\sigma$. We also find a 21% tighter constraint on $S_8$ and a 29% tighter constraint on $\Omega_\mathrm{m}$ compared to our fiducial analysis. This work shows the power and potential of joint small-scale galaxy clustering and galaxy-galaxy lensing analyses using SHAMe.