Status of HI searches for CHVCs beyond the Local Group

Growing evidence supports the suggestion that the compact high-velocity clouds of H i (CHVCs) are located throughout the Local Group and continue to fuel galactic evolution. Recent distance estimates to individual objects lie in the range 150-850 kpc, implying an H i mass range of $10^{5.7}\rightarr...

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Bibliographic Details
Published in:Astronomy and astrophysics (Berlin) 2001-08, Vol.375 (1), p.219-226
Main Authors: Braun, R., Burton, W. B.
Format: Article
Language:English
Subjects:
galaxies: dwarf
galaxies: Local Group
galaxy: evolution
galaxy: formation
ISM: atoms
ISM: clouds
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Summary:Growing evidence supports the suggestion that the compact high-velocity clouds of H i (CHVCs) are located throughout the Local Group and continue to fuel galactic evolution. Recent distance estimates to individual objects lie in the range 150-850 kpc, implying an H i mass range of $10^{5.7}\rightarrow10^{7.2} M_\odot$ together with sizes ranging from 2-12 kpc, while the average linewidth is 30 km s-1 FWHM. It is natural to ask whether objects of this type would not already have been seen by current blind H i surveys of the extragalactic sky. We consider the properties of the deepest published surveys of this type and conclude that the sensitivity and coverage have now begun to reveal the high mass end of the distribution ($M_{\rm HI}> 10^{7} M_\odot$). Achieving detection limits an order of magnitude deeper should finally enable direct study of these systems beyond the Local Group, or definitively rule out their existence.
ISSN:0004-6361
1432-0746
DOI:10.1051/0004-6361:20010810