Neutral Gas Accretion onto Nearby Galaxies

TL;DR

This paper investigates starless gas clouds around nearby galaxies, finding that such accreting gas is mainly detected near large galaxies within their circumgalactic medium, highlighting the rarity of starless gas accretion.

Contribution

It provides an inventory and analysis of starless gas clouds in the Local Group, emphasizing their distribution and detection likelihood near large galaxies.

Findings

Starless gas clouds are mostly found within the circumgalactic medium of large galaxies.

Detection of starless gas clouds is more probable close to galaxies.

Starless gas accretion is rare outside the circumgalactic environment.

Abstract

While there is no lack of evidence for the accretion of stellar systems onto nearby galaxies, direct evidence for the accretion of gas without stars is scarce. Here we consider an inventory of starless gas "clouds" in and around galaxies of the Local Group to discern their general properties and see how they might appear in distant systems. The conclusion is that accreting gas without stars is detected almost entirely within the circumgalactic medium of large galaxies and is rare otherwise. If our Local Group is any example, the best place to detect starless gas clouds is relatively close to galaxies.