Free-floating molecular clumps and gas mixing: hydrodynamic aftermaths of the intracluster$-$interstellar medium interaction

TL;DR

This study uses high-resolution simulations to explore how gas-rich galaxies interacting with the intra-cluster medium produce molecular gas clumps, affecting galaxy evolution and intracluster gas composition.

Contribution

It provides new insights into the formation, evolution, and properties of molecular gas clumps resulting from galaxy-ICM interactions in clusters.

Findings

Over a hundred molecular gas clumps can form in galaxy tails.

Clump lifetimes are typically less than 300 million years.

ICM gas significantly alters the composition of galaxy disks after crossing the cluster.

Abstract

The interaction of gas-rich galaxies with the intra-cluster medium (ICM) of galaxy clusters has a remarkable impact on their evolution, mainly due to the gas loss associated with this process. In this work, we use an idealised, high-resolution simulation of a Virgo-like cluster, run with RAMSES and with dynamics reproducing that of a zoom cosmological simulation, to investigate the interaction of infalling galaxies with the ICM. We find that the tails of ram pressure stripped galaxies give rise to a population of up to more than a hundred clumps of molecular gas lurking in the cluster. The number count of those clumps varies a lot over time -- they are preferably generated when a large galaxy crosses the cluster (M$_{200c} > 10^{12}$ M$_\odot$), and their lifetime ($\lesssim 300$ Myr) is small compared to the age of the cluster. We compute the intracluster luminosity associated with the star formation which takes place within those clumps, finding that the stars formed in all of the galaxy tails combined amount to an irrelevant contribution to the intracluster light. Surprisingly, we also find in our simulation that the ICM gas significantly changes the composition of the gaseous disks of the galaxies: after crossing the cluster once, typically 20% of the cold gas still in those disks comes from the ICM.