ΛCDM Satellites and H I Companions—the Arecibo ALFA Survey of NGC 2903

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Abstract
  • 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 MilkyWay 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 2×105M and column density of 2 × 1017 cm−2 at the 3 σ 2δ 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 newdiscovery with anHi mass of 2.6×106M . The companion is 64 kpc fromNGC2903 in
    projection, is likely associated with a small optical galaxy of similar total stellarmass, and is darkmatter 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.
TitleΛCDM Satellites and H I Companions—the Arecibo ALFA Survey of NGC 2903
CreatorCatinella, B.
Brinks, E.
de Blok, W. J. G.
Davies, J.
Linder, S. M.
Momjian, E.
Giovanelli, R.
Haynes, M. P.
van Driel, W.
Irwin, J. A.
Koribalski, B. S.
Hoffman, G. Lyle
Putman, M. E.
Spekkens, K.
PublisherAstrophysical Journal
Academic DepartmentPhysics
DivisionNatural Sciences
OrganizationLafayette College
Date IssuedFebruary 20, 2009
Date Available2010-01-08T15:09:50Z
TypeArticle
LanguageEnglish
Keyworddark matter
galaxies: individual (NGC 2903)
radio lines: ISM
galaxies: spiral
galaxies: formation
Bibliographic CitationIrwin, J. A., G. L. Hoffman, et al. (2009). "ΛCDM Satellites and H I Companions—the Arecibo ALFA Survey of NGC 2903." Astrophysical Journal 692: 1447-1463.
Standard IdentifierHandle 10385/543
DOI 10.1088/0004-637X/692/2/1447
Permalinkhttp://hdl.handle.net/10385/543
Rights Statement In Copyright In Copyright
Rights HoldersAmerican Astronomical Society
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