The Origin of Neutral Hydrogen Clouds in Nearby Galaxy Groups: Exploring   the Range Of Galaxy Interactions
  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. 
Katie M. Chynoweth (1), Kelly Holley-Bockelmann (2 and 3), Emil   Polisensky (4), and Glen Langston (5) ((1) NRC Postdoc at ...
astro-ph.CO astro-ph.GA