A DARK GALAXY IN THE VIRGO CLUSTER IMAGED AT 21-CM

  • R. Minchin
  • M. J. Disney
  • J. I. Davies
  • A. R. Marble
  • C. D. Impey
  • P. J. Boyce
  • D. A. Garcia
  • M. Grossi
  • C. A. Jordan
  • R. H. Lang
  • S. Roberts
  • S. Sabatini
  • W. van Driel
Part of the Astrophysics and Space Science Proceedings book series (ASSSP)

Abstract

Dark Matter supposedly dominates the extragalactic Universe (Peebles 1993; Peacock 1998; Moore et al. 1999; D’Onghi & Lake 2004), yet no dark structure of galactic proportions has ever been convincingly identified. Earlier (Minchin et al. 2005) we suggested that VIRGOHI 21, a 21-cm source we found in the Virgo Cluster at Jodrell Bank using single-dish observations (Davies et al. 2004), was probably such a dark galaxy because of its broad line-width (~200 km s-1) unaccompanied by any visible gravitational source to account for it. We have now imaged VIRGOHI 21 in the neutral-hydrogen line, and have found what appears to be a dark, edge-on, spinning disc with the mass and diameter of a typical spiral galaxy. Moreover the disc has unquestionably interacted with NGC 4254, a luminous spiral with an odd one-armed morphology, but lacking the massive interactor normally linked with such a feature. Published numerical models (Vollmer et al. 2005) of NGC 4254 call for a close interaction ~108 years ago with a perturber of ~1011 solar masses. This we take as further, independent evidence for the massive nature of VIRGOHI 21.

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Copyright information

© Springer 2007

Authors and Affiliations

  • R. Minchin
    • 1
    • 2
  • M. J. Disney
    • 2
  • J. I. Davies
    • 2
  • A. R. Marble
    • 3
  • C. D. Impey
    • 3
  • P. J. Boyce
    • 2
  • D. A. Garcia
    • 2
  • M. Grossi
    • 2
  • C. A. Jordan
    • 4
  • R. H. Lang
    • 2
  • S. Roberts
    • 2
  • S. Sabatini
    • 5
  • W. van Driel
    • 6
  1. 1.Arecibo ObservatoryPuerto Rico
  2. 2.School of Physics and AstronomyCardiff UniversityUK
  3. 3.Steward ObservatoryUniversity of ArizonaTucsonUSA
  4. 4.Jodrell Bank ObservatoryUniversity of ManchesterUK
  5. 5.Osservatorio Astronomico di RomaItaly
  6. 6.Observatoire de ParisParisFrance

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