The Origin of Neutral Hydrogen Clouds in Nearby Galaxy Groups: Exploring the Range Of Galaxy Interactions

TL;DR

This study combines simulations and deep HI observations of nearby galaxy groups to investigate the origins of neutral hydrogen clouds, finding they are likely produced by recent galaxy interactions rather than dark matter minihalos.

Contribution

It provides new observational data and simulation analysis to distinguish between HI cloud formation mechanisms in galaxy groups.

Findings

No HI clouds detected in the studied groups.

HI clouds are likely formed through recent galaxy interactions.

No evidence found linking HI clouds to dark matter halos above 10^6 M_Sun.

Abstract

We combine high resolution N-body simulations with deep observations of neutral hydrogen (HI) in nearby galaxy groups in order to explore two well-known theories of HI cloud formation: HI stripping by galaxy interactions and dark matter minihalos with embedded HI gas. This paper presents new data from three galaxy groups, Canes Venatici I, NGC 672, and NGC 45, and assembles data from our previous galaxy group campaign to generate a rich HI cloud archive to compare to our simulated data. We find no HI clouds in the Canes Venatici I, NGC 672, or NGC 45 galaxy groups. We conclude that HI clouds in our detection space are most likely to be generated through recent, strong galaxy interactions. We find no evidence of HI clouds associated with dark matter halos above M_HI = 10^6 M_Sun, within +/- 700 km/s of galaxies, and within 50 kpc projected distance of galaxies.