Ram pressure stripping the hot gaseous halos of galaxies in groups and clusters

TL;DR

This study uses hydrodynamic simulations and a simple analytic model to understand how ram pressure strips hot gaseous halos of galaxies in groups and clusters, revealing that a significant fraction can remain after 10 Gyr.

Contribution

It introduces a new, physically motivated analytic model for ram pressure stripping of spherical hot gas halos, validated against detailed simulations.

Findings

Approximately 30% of hot halo gas remains after 10 Gyr for typical parameters.

The analytic model predicts stripping within 10% accuracy across various scenarios.

Stripping efficiency depends on orbit, galaxy mass, and structural properties.

Abstract

We use a large suite of carefully controlled full hydrodynamic simulations to study the ram pressure stripping of the hot gaseous halos of galaxies as they fall into massive groups and clusters. The sensitivity of the results to the orbit, total galaxy mass, and galaxy structural properties is explored. For typical structural and orbital parameters, we find that ~30% of the initial hot galactic halo gas can remain in place after 10 Gyr. We propose a physically simple analytic model that describes the stripping seen in the simulations remarkably well. The model is analogous to the original formulation of Gunn & Gott (1972), except that it is appropriate for the case of a spherical (hot) gas distribution (as opposed to a face-on cold disk) and takes into account that stripping is not instantaneous but occurs on a characteristic timescale. The model reproduces the results of the simulations to within approximately 10% at almost all times for all the orbits, mass ratios, and galaxy structural properties we have explored. The one exception involves unlikely systems where the orbit of the galaxy is highly non-radial and its mass exceeds about 10% of the group or cluster into which it is falling (in which case the model under-predicts the stripping following pericentric passage). The proposed model has several interesting applications, including modelling the ram pressure stripping of both observed and cosmologically-simulated galaxies and as a way to improve current semi-analytic models of galaxy formation. One immediate consequence is that the colours and morphologies of satellite galaxies in groups and clusters will differ significantly from those predicted with the standard assumption of complete stripping of the hot coronae.