The halo model with beyond-linear halo bias: unbiasing cosmological constraints from galaxy-galaxy lensing and clustering

TL;DR

This paper shows that ignoring non-linear halo bias in galaxy-galaxy lensing and clustering analyses can cause significant biases in cosmological parameters, emphasizing the need for beyond-linear bias corrections.

Contribution

It introduces a beyond-linear halo bias correction method to improve the accuracy of cosmological parameter estimation from large-scale structure data.

Findings

Ignoring non-linear halo bias causes up to 5σ offsets in parameters.

Including scales down to 0.05 Mpc/h is crucial for accurate results.

Beyond-linear bias correction reduces systematic biases in cosmological constraints.

Abstract

We determine the error introduced in a joint halo model analysis of galaxy-galaxy lensing and galaxy clustering observables when adopting the standard approximation of linear halo bias. Considering the Kilo-Degree Survey, we forecast that ignoring the non-linear halo bias would result in up to 5$\sigma$ offsets in the recovered cosmological parameters describing structure growth, $S_8$, and the matter density parameter, $\Omega_{\mathrm{m}}$. We include the scales $10^{-1.3}<r_{\rm{p}} \ / h^{-1}\, \mathrm{Mpc}<10$ in the data vector, and the direction of these offsets are shown to depend on the freedom afforded to the halo model through other nuisance parameters. We conclude that a beyond-linear halo bias correction must therefore be included in future cosmological halo model analyses of large-scale structure observables on non-linear scales.