期刊
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
卷 415, 期 2, 页码 1883-1894出版社
OXFORD UNIV PRESS
DOI: 10.1111/j.1365-2966.2011.18833.x
关键词
galaxies: general; galaxies: groups: individual: NGC 7448; galaxies: ISM; radio lines: ISM
资金
- National Aeronautics and Space Administration
- UK Science and Technology Facilities Council.
- US Government [NAG W-2166]
- National Science Foundation
- National Geographic Society
- Sloan Foundation
- Samuel Oschin Foundation
- Eastman Kodak Corporation
- UK Science and Engineering Research Council (later the UK Particle Physics and Astronomy Research Council)
- Alfred P. Sloan Foundation
- US Department of Energy
- Japanese Monbukagakusho
- Max Planck Society
- Higher Education Funding Council for England
- American Museum of Natural History
- Astrophysical Institute Potsdam
- University of Basel
- University of Cambridge
- Case-Western Reserve University
- University of Chicago
- Drexel University
- Fermilab
- Institute for Advanced Study
- Japan Participation Group
- Johns Hopkins University
- Joint Institute for Nuclear Astrophysics
- Kavli Institute for Particle Astrophysics and Cosmology
- Korean Scientist Group
- Chinese Academy of Sciences (LAMOST)
- Los Alamos National Laboratory
- Max-Planck-Institute for Astronomy (MPIA)
- Max-Planck-Institute for Astrophysics (MPA)
- New Mexico State University
- Ohio State University
- University of Pittsburgh
- University of Portsmouth
- Princeton University
- United States Naval Observatory
- University of Washington
In this paper we describe results from the Arecibo Galaxy Environments Survey (AGES). The survey reaches column densities of similar to 3 x 10(18) cm(-2) and masses of similar to 10(7) M-circle dot, over individual regions of order 10 deg(2) in size, out to a maximum velocity of 18 000 km s(-1). Each surveyed region is centred on a nearby galaxy, group or cluster, in this instance the NGC 7448 group. Galaxy interactions in the NGC 7448 group reveal themselves through the identification of tidal tails and bridges. We find similar to 2.5 times more atomic gas in the intergalactic medium than in the group galaxies. We identify five new dwarf galaxies, two of which appear to be members of the NGC 7448 group. This is too small, by roughly an order of magnitude, a number of dwarf galaxies to reconcile observation with theoretical predictions of galaxy formation models. If they had observed this region of the sky in previous wide-area blind H I surveys, HIPASS and ALFALFA, they would have detected only 5 and 43 per cent, respectively, of the galaxies we have detected, missing a large fraction of the atomic gas in this volume. We combine the data from this paper with that from our other AGES papers (370 galaxies) to derive an H I mass function with the following Schechter function parameters: alpha = -1.52(+/- 0.05), M* = 5.1(+/- 0.3) x 10(9) h(72)(-2) M-circle dot, phi = 8.6(+/- 1.1) x 10(-3) h(72)(3) Mpc(-3) dex(-1). Integrating the mass function leads to a cosmic mass density of atomic hydrogen of Omega(H I) = 5.3(+/- 0.8) x 10(-4) h(72)(-1). Our mass function is steeper than that found by both HIPASS and ALFALFA (alpha = 1.37 and 1.33, respectively), while our cosmic mass density is consistent with ALFALFA, but 1.7 times larger than found by HIPASS.
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