Emulation of baryonic effects on the matter power spectrum and constraints from galaxy cluster data

TL;DR

This paper introduces a baryonic emulator for the matter power spectrum that accurately models baryonic feedback effects, enabling better interpretation of galaxy survey data and constraints on baryonic processes.

Contribution

We develop a baryonic emulator based on the baryonification model, connecting gas and stellar fractions to power spectrum suppression, with improved precision and reduced parameter set.

Findings

The emulator recovers hydro simulation spectra at sub-percent accuracy.

It constrains baryonic suppression to over 1% at certain scales.

Maximum suppression reaches 20-28% at small scales.

Abstract

Baryonic feedback effects consist of a major systematic for upcoming weak-lensing and galaxy-clustering surveys. In this paper, we present an emulator for the baryonic suppression of the matter power spectrum. The emulator is based on the baryonification model, containing seven free parameters that are connected to the gas profiles and stellar abundances in haloes. We show that with the baryonic emulator, we can not only recover the power spectra of hydro-dynamical simulations at sub-percent precision but also establish a connection between the baryonic suppression of the power spectrum and the gas and stellar fractions in haloes. This connection allows us to predict the expected deviation from a dark-matter-only power spectrum using measured X-ray gas fractions of galaxy groups and clusters. With these measurements, we constrain the suppression to exceed the percent-level at k = 0.1-0.4 h/Mpc and to reach a maximum of 20-28 percent at around k = 7 h/Mpc (68 percent confidence level). As a further step, we also perform a detailed parameter study and we present a minimum set of four baryonic parameters that are required to recover the scale and redshift dependence observed in hydro-dynamical simulations. The baryonic emulator can be found at https://github.com/sambit-giri/BCemu.