Gas accretion and Ram Pressure Stripping of Haloes in Void Walls

TL;DR

This study uses hydrodynamical simulations to explore how large-scale gas flows in void walls affect galaxy gas accretion and stripping, revealing that some haloes experience partial gas loss due to ram pressure effects.

Contribution

It provides new insights into the impact of large-scale flows on halo gas accretion and stripping in void environments, combining simulations with analytical modeling.

Findings

Approximately 10% of haloes near void walls cannot accrete gas due to fast flows.

Low-mass haloes often experience partial gas stripping, affecting their growth.

Gas morphology shows jellyfish-like structures indicating ongoing gas removal.

Abstract

We conduct hydrodynamical cosmological zoom simulations of fourteen voids to study the ability of haloes to accrete gas at different locations throughout the voids at z = 0. Measuring the relative velocity of haloes with respect to their ambient gas, we find that a tenth of the haloes are expected to be unable to accrete external gas due to its fast flow passed them (so called 'fast flow haloes'). These are typically located near void walls. We determine that these haloes have recently crossed the void wall and are still moving away from it. their motion counter to that of ambient gas falling towards the void wall results in fast flows that make external gas accretion very challenging, and often cause partial gas loss via the resultant ram pressures. Using an analytical approach, we model the impact of such ram pressures on the gas inside haloes of different masses. A halo's external gas accretion is typically cut off, with partial stripping of halo gas. For masses below a few times 10$^{9}$ M$_{\odot}$, their halo gas is heavily truncated but not completely stripped. We identify numerous examples of haloes with a clear jelly-fish like gas morphology, indicating their surrounding gas is being swept away, cutting them off from further external accretion. These results highlight how, even in the relatively low densities of void walls, a fraction of galaxies can interact with large-scale flows in a manner that has consequences for their gas content and ability to accrete gas.