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Publication Details
AFRICAN RESEARCH NEXUS
SHINING A SPOTLIGHT ON AFRICAN RESEARCH
earth and planetary sciences
ΛcDM satellites and H I companions - The Arecibo ALFA survey of NGC 2903
Astrophysical Journal, Volume 692, No. 2, Year 2009
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Description
We have conducted a deep, complete H I survey, using Arecibo/Arecibo L-band Feed Array (ALFA), of a field centered on the nearby, isolated galaxy, NGC 2903, which is similar to the Milky Way in its properties. The field size was 150 kpc × 260 kpc and the final velocity range spanned from 100 to 1133 km s-1. The ALFA beams have been mapped as a function of azimuth and cleaned from each azimuth-specific cube prior to forming final cubes. The final H I data are sensitive down to an H I mass of 2 × 105 M ⊙ and column density of 2 × 1017 cm -2 at the 3 σ 2 δ V level, where σ is the rms noise level and δ V is the velocity resolution. NGC 2903 is found to have an H I envelope that is larger than previously known, extending to at least three times the optical diameter of the galaxy. Our search for companions yields one new discovery with an H I mass of 2.6 × 106 M⊙. The companion is 64 kpc from NGC 2903 in projection, is likely associated with a small optical galaxy of similar total stellar mass, and is dark matter dominated, with a total mass >108 M⊙. In the region surveyed, there are now two known companions: our new discovery and a previously known system that is likely a dwarf spheroidal, lacking H I content. If H I constitutes 1% of the total mass in all possible companions, then we should have detected 230 companions, according to Λ cold dark matter (ΛCDM) predictions. Consequently, if this number of dark-matter clumps are indeed present, then they contain less than 1% H I content, possibly existing as very faint dwarf spheroidals or as starless, gasless dark-matter clumps. © 2009. The American Astronomical Society. All rights reserved.
Authors & Co-Authors
Irwin, Judith A.
Canada, Kingston
Queen’s University
Hoffman, G. Lyle
United States, Easton
Lafayette College
Spekkens, Kristine
Canada, Kingston
Royal Military College of Canada
Haynes, Martha P.
United States, Ithaca
Cornell Center for Astrophysics and Planetary Science
United States, Ithaca
National Astronomy and Ionosphere Center, new York
Giovanelli, Riccardo
United States, Ithaca
Cornell Center for Astrophysics and Planetary Science
United States, Ithaca
National Astronomy and Ionosphere Center, new York
Linder, Suzanne M.
Germany, Hamburg
Universität Hamburg
Catinella, Barbara
Germany, Garching Bei Munchen
Max Planck Institute for Astrophysics
Puerto Rico, Rico
Naic/arecibo Observatory
Momjian, Emmanuel
Puerto Rico, Rico
Naic/arecibo Observatory
United States, Socorro
National Radio Astronomy Observatory Socorro
Koribalski, Baerbel S.
Australia, Sydney
Australia Telescope National Facility
Davies, Jonathan I.
United Kingdom, Cardiff
Cardiff University
Brinks, Elias
United Kingdom, Hatfield
University of Hertfordshire
de Blök, Willem J.G.
South Africa, Cape Town
University of Cape Town
Putman, Mary E.
United States, New York
Columbia University
van Driel, Willem
France, Paris
L'observatoire de Paris
Statistics
Citations: 23
Authors: 14
Affiliations: 15
Identifiers
Doi:
10.1088/0004-637X/692/2/1447
ISSN:
0004637X
e-ISSN:
15384357
Study Design
Cross Sectional Study
Study Approach
Quantitative