The THREEHUNDRED project: the effect of baryon processes at galaxy cluster scale

TL;DR

This study investigates how different baryon physics models in hydrodynamic simulations affect galaxy cluster masses and halo mass functions, revealing small but model-dependent variations that impact cosmological constraints.

Contribution

It provides a detailed comparison of baryon model effects on cluster mass and halo mass functions using multiple hydrodynamic simulations from the THREEHUNDRED project.

Findings

Mass changes due to baryon models are at a few percent level.

Mass changes can be positive or negative depending on the baryon model.

Small mass variations have a weak impact on halo counts and mass functions.

Abstract

The role of baryon models played in hydrodynamic simulations is still unclear. Future surveys that use cluster statistics to precisely constrain cosmology models require a better understanding of that. With the hydro-simulated galaxy clusters from different baryon models (Gadget-MUSIC, Gadget-X and Gizmo-SIMBA) from the THREEHUNDRED project, we can look into more details of this question. We find that the galaxy cluster mass change due to different baryon models is at a few per cent level. However, the mass changes can be positive or negative, which is depending on the baryon models. Such a small mass change leaves a weak influence (slightly larger compared to the mass changes) on both the cumulative halo numbers and the differential halo mass function (HMF) above the mass completeness. Agreed to the halo mass change, the halo mass (or HMF) can be increased or decreased with respect to the dark-matter-only (DMO) run depending on the baryon models.