HIghMass - High HI Mass, HI-Rich Galaxies at z∼0: Combined HI and H2 Observations

Gregory Hallenbeck, Shan Huang, Kristine Spekkens, Martha P. Haynes, Riccardo Giovanelli, Elizabeth A. K. Adams, Jarle Brinchmann, John Carpenter, Jayaram Chengalur, Leslie K. Hunt, Karen L. Masters, Amélie Saintonge

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We present resolved  and CO observations of three galaxies from the HIghMass sample, a sample of H I-massive (MH I > 1010 MΘ), gas-rich (MH I in the top 5% for their M *) galaxies identified in the ALFALFA survey. Despite their high gas fractions, these are not low-surface-brightness galaxies and have typical specific star formation rates (SFR/M*) for their stellar masses. The three galaxies have normal SFRs for their H2 masses, but unusually short star formation efficiency scale lengths, indicating that the star formation bottleneck in these galaxies is in the conversion of H I to H2, not in converting  to stars. In addition, their dark matter spin parameters (λ) are above average, but not exceptionally high, suggesting that their star formation has been suppressed over cosmic time but is now becoming active, in agreement with prior Hα observations.

Original languageEnglish
Article number225
JournalThe Astronomical Journal
Issue number6
Publication statusPublished - 7 Dec 2016


  • astro-ph.GA
  • galaxies: evolution
  • galaxies: individual (UGC 6168, UGC 7899, NGC 5230)
  • galaxies: spiral
  • radio lines: galaxies


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