Gas stripping and mixing in galaxy clusters: A numerical comparison study

TL;DR

This study compares different numerical methods for simulating gas stripping and mixing in galaxy clusters, finding that Voronoi particle hydrodynamics (VPH) predicts faster gas stripping than traditional SPH, aligning better with moving-mesh results.

Contribution

The paper introduces and evaluates VPH as an alternative to SPH, demonstrating its improved accuracy in simulating gas stripping in galaxy clusters compared to traditional SPH methods.

Findings

VPH predicts faster gas stripping than SPH.

VPH results align more closely with moving-mesh code.

VPH offers a promising balance between accuracy and computational efficiency.

Abstract

The ambient hot intra-halo gas in clusters of galaxies is constantly fed and stirred by in-falling galaxies, a process that can be studied in detail with cosmological hydro- dynamical simulations. However, different numerical methods yield discrepant predic- tions for crucial hydrodynamical processes, leading for example to different entropy profiles in clusters of galaxies. In particular, the widely used Lagrangian smoothed particle hydrodynamics (SPH) scheme is suspected to strongly damp fluid instabili- ties and turbulence, which are both crucial to establish the thermodynamic structure of clusters. In this study, we test to which extent our recently developed Voronoi particle hydrodynamics (VPH) scheme yields different results for the stripping of gas out of infalling galaxies, and for the bulk gas properties of cluster. We consider both the evolution of isolated galaxy models that are exposed to a stream of intra cluster medium or are dropped into cluster models, as well as non-radiative cosmological sim- ulations of cluster formation. We also compare our particle-based method with results obtained with a fundamentally different discretisation approach as implemented in the moving-mesh code AREPO. We find that VPH leads to noticeably faster stripping of gas out of galaxies than SPH, in better agreement with the mesh-code than with SPH. We show that despite the fact that VPH in its present form is not as accurate as the moving mesh code in our investigated cases, its improved accuracy of gradient estimates makes VPH an attractive alternative to SPH.