Removal and mixing of the coronal gas from satellites in galaxy groups: cooling the intragoup gas

TL;DR

This paper investigates how interactions between satellite and host galaxy coronae can create a warm gas phase with shorter cooling times, potentially leading to new star formation modes in galaxy groups.

Contribution

It introduces a novel analysis combining analytic estimates and high-resolution simulations to show how coronal interactions produce a warm phase with rapid cooling, influencing galaxy evolution.

Findings

Mixing of coronae creates a warm phase with shorter cooling times.

Turbulence from Kelvin-Helmholtz instability facilitates gas mixing.

Potential for in situ star formation or cold gas accretion in galaxy groups.

Abstract

The existence of an extended hot gaseous corona surrounding clusters, groups and massive galaxies is well established by observational evidence and predicted by current theories of galaxy formation. When a small galaxy collides with a larger one, their coronae are the first to interact, producing disturbances that remove gas from the smaller system and settle it into the corona of the larger one. For a Milky-Way-size galaxy merging into a low-mass group, ram pressure stripping and the Kelvin-Helmholtz instability are the most relevant of these disturbances. We argue that the turbulence generated by the latter mixes the material of both coronae in the wake of the orbiting satellite creating a "warm phase" mixture with a cooling time a factor of several shorter than that of the ambient intragroup gas. We reach this conclusion using analytic estimates, as well as adiabatic and dissipative high resolution numerical simulations of a spherical corona subject to the ablation process of a constant velocity wind with uniform density and temperature. Although this is a preliminary analysis, our results are promising and we speculate that the mixture could potentially trigger in situ star formation and/or be accreted into the central galaxy as a cold gas flow resulting in a new mode of star formation in galaxy groups and clusters.