The Three Hundred Project: The gas disruption of infalling objects in cluster environments

TL;DR

This study investigates how infalling haloes in galaxy clusters lose their gas content, revealing a characteristic radius where gas stripping occurs, influenced by host mass and infall timing, based on analysis of the Three Hundred project simulations.

Contribution

It provides a detailed analysis of gas loss in infalling haloes within clusters, identifying key radial trends and the influence of host mass and pre-processing effects, which advances understanding of galaxy evolution in dense environments.

Findings

Infalling haloes lose nearly all gas around 1.7R200 in 3D and at R200 in projection.

Gas stripping correlates with time since infall, cluster-centric distance, and host mass.

Subhaloes in group and low-mass hosts follow similar gas-loss trends as their hosts.

Abstract

We analyse the gas content evolution of infalling haloes in cluster environments from THE THREE HUNDRED project, a collection of 324 numerically modelled galaxy clusters. The haloes in our sample were selected within $5R_{200}$ of the main cluster halo at $z=0$ and have total halo mass $M_{200}\geq10^{11} h^{-1} M_{\odot}$. We track their main progenitors and study their gas evolution since their crossing into the infall region, which we define as $1-4R_{200}$. Studying the radial trends of our populations using both the full phase space information and a line-of-sight projection, we confirm the Arthur et al. (2019) result and identify a characteristic radius around $1.7R_{200}$ in 3D and at $R_{200}$ in projection at which infalling haloes lose nearly all of the gas prior their infall. Splitting the trends by subhalo status we show that subhaloes residing in group-mass and low-mass host haloes in the infall region follow similar radial gas-loss trends as their hosts, whereas subhaloes of cluster-mass host haloes are stripped of their gas much further out. Our results show that infalling objects suffer significant gaseous disruption that correlates with time-since-infall, cluster-centric distance and host mass, and that the gaseous disruption they experience is a combination of subhalo pre-processing and object gas depletion at a radius which behaves like an accretion shock.