TheThreeHundred Project: ram pressure and gas content of haloes and subhaloes in the phase-space plane

Jake Arthur,Klaus Dolag,Frazer R Pearce,Lilian Garratt-Smithson,Gustavo Yepes,Lyndsay J Old,Marco De Petris,Chris Power,Meghan E Gray,Elena Rasia,Alexander Knebe,Adam R H Stevens,Weiguang Cui,Pascal J Elahi,Alexander Arth

doi:10.1093/mnras/stz212

Abstract

We use TheThreeHundred project, a suite of 324 resimulated massive galaxy clusters embedded in a broad range of environments, to investigate (i) how the gas content of surrounding haloes correlates with phase-space position at $z=0$, and (ii) to investigate the role that ram pressure plays in this correlation. By stacking all 324 normalised phase-space planes containing 169287 haloes and subhaloes, we show that the halo gas content is tightly correlated with phase-space position. At $\sim\,1.5-2\,\text{R}_{\text{200}}$ of the cluster dark matter halo, we find an extremely steep decline in the halo gas content of infalling haloes and subhaloes irrespective of cluster mass, possibly indicating the presence of an accretion shock. We also find that subhaloes are particularly gas-poor, even in the cluster outskirts, which could indicate active regions of ongoing pre-processing. By modelling the instantaneous ram pressure experienced by each halo and subhalo at $z=0$, we show that the ram pressure intensity is also well correlated with phase-space position, which is again irrespective of cluster mass. In fact, we show that regions in the phase-space plane with high differential velocity between a halo or subhalo and its local gas environment, are almost mutually exclusive with high halo gas content regions. This suggests a causal link between the gas content of objects and the instantaneous ram pressure they experience, where the dominant factor is the differential velocity.

Highlights

In the ΛCDM paradigm dense structures, such as galaxy clusters, grow hierarchically via gravitational attraction (White & Rees 1978)
SUMMARY AND CONCLUSIONS We use TheThreeHundred project, a suite of 324 resimulated massive galaxy clusters embedded in a broad range of environments, to investigate how the gas content of surrounding haloes and subhaloes correlates with phase-space position at z = 0
We have studied how the instantaneous ram pressure experienced by these objects varies across the phase-space plane and what role it plays in the gas content of these objects at z = 0

Summary

Introduction

In the ΛCDM paradigm dense structures, such as galaxy clusters, grow hierarchically via gravitational attraction (White & Rees 1978). In light of this limitation, many recent theoretical efforts have been directed towards producing statistically significant sets of rich clusters using zoomed simulations; including but not limited to, Rhapsody-G (Hahn et al 2015), Hydrangea (Bahe et al 2017), C-Eagle (Barnes et al 2017), and most recently, the TheThreeHundred project (Cui et al 2018) Simulations such as these have become important tools for studying galaxy evolution in high density environments, as we know that environmental effects are of interest within the centre of rich galaxy clusters, and in the faint outskirts, which is difficult to observe

Methods

Results

Conclusion