The impact of galaxy bias on cross-correlation tomography

TL;DR

This paper demonstrates that robust, bias-independent estimators for tomographic measurements of galaxy and large-scale structure can be constructed, enabling high-precision reconstruction of cosmic quantities across redshifts using simulations.

Contribution

It introduces a method to extract galaxy bias-independent tomographic measurements, validated with simulations, improving the interpretation of large-scale structure data.

Findings

Reconstructed $P_e$ and $ ho_{ m SFR}$ with 1-3% accuracy across redshifts.

Developed bias-independent estimators for galaxy clustering measurements.

Validated the approach using FLAMINGO hydrodynamic simulations.

Abstract

The cross-correlation of galaxies at different redshifts with other tracers of the large-scale structure can be used to reconstruct the cosmic mean of key physical quantities, and their evolution over billions of years, at high precision. However, a correct interpretation of these measurements must ensure that they are independent of the clustering properties of the galaxy sample used. In this paper we explore different prescriptions to extract tomographic reconstruction measurements and use the FLAMINGO hydrodynamic simulations to show that a robust estimator, independent of the small-scale galaxy bias, can be constructed. We focus on the tomographic reconstruction of the halo bias-weighted electron pressure $\langle bP_e\rangle$ and star-formation density $\langle b\rho_{\rm SFR}\rangle$, which can be reconstructed from tomographic analysis of Sunyaev-Zel'dovich and cosmic infrared background maps, respectively. We show that these quantities can be reconstructed with an accuracy of 1-3\% over a wide range of redshifts, using different galaxy samples. We also show that these measurements can be accurately interpreted using the halo model, assuming a sufficiently reliable model can be constructed for the halo mass function, large-scale halo bias, and for the dependence of the physical quantities being reconstructed on halo mass.