Volume 382, Number 1, JanuaryIV 2002
|Page(s)||43 - 52|
|Section||Cosmology (including clusters of galaxies)|
|Published online||15 January 2002|
An survey of the Centaurus and Sculptor groups
Constraints on the space density of low mass galaxies
Australia Telescope National Facility, PO Box 76, Epping, NSW 1710, Australia
2 School of Physics, Univ. of Melbourne, Parkville, VIC 3052, Australia
3 Kapteyn Astronomical Institute, PO Box 800, 9700 AV Groningen, The Netherlands
4 Research School of Astronomy & Astrophysics, Mount Stromlo Observatory, Cotter Road, Weston ACT 2611, Australia
Corresponding author: W. J. G. de Blok, firstname.lastname@example.org
Accepted: 7 November 2001
We present results of two 21-cm surveys performed with the Australia Telescope Compact Array in the nearby Centaurus A and Sculptor galaxy groups. These surveys are sensitive to compact clouds and galaxies with masses as low as ~, and are therefore among the most sensitive extragalactic surveys to date. The surveys consist of sparsely spaced pointings that sample approximately 2% of the groups' area on the sky. We detected previously known group members, but we found no new clouds or galaxies down to the sensitivity limit of the surveys. If the mass function had a faint end slope of below in these groups, we would have expected ~ new objects. Cold dark matter theories of galaxy formation predict the existence of a large number low mass dark matter sub-halos that might appear as tiny satellites in galaxy groups. Our results support and extend similar conclusions derived from previous surveys that a rich population of these satellites does not exist.
Key words: ISM: clouds / intergalactic medium / galaxies: luminosity function, mass function / radio lines: ISM
© ESO, 2002
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