TY - JOUR
T1 - 21 cm Synthesis observations of VIRGOHI 21 - A possible dark galaxy in the virgo cluster
AU - Minchin, Robert
AU - Davies, Jonathan
AU - Disney, Michael
AU - Grossi, Marco
AU - Sabatini, Sabina
AU - Boyce, Peter
AU - Garcia, Diego
AU - Impey, Chris
AU - Jordan, Christele
AU - Lang, Robert
AU - Marble, Andrew
AU - Roberts, Sarah
AU - Van Driel, Wim
PY - 2007/12/1
Y1 - 2007/12/1
N2 - Many observations indicate that dark matter dominates the extragalactic universe, yet no totally dark structure of galactic proportions has ever been convincingly identified. Previously, we have suggested that VIRGOHI 21, a 21 cm source we found in the Virgo Cluster using Jodrell Bank, was a possible 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 VERGOHI 21 in the neutral hydrogen line and find what could be a dark, edge-on, spinning disk with the mass and diameter of a typical spiral galaxy. Moreover, VIRGOHI 21 has unquestionably been involved in an interaction with NGC 4254, a luminous spiral with an odd one-armed morphology, but lacking the massive interactor normally linked with such a feature. Numerical models of NGC 4254 call for a close interaction ∼108 yr ago with a perturber of ∼1011 M⊙. This we take as additional evidence for the massive nature of VERGOHI 21, as there does not appear to be any other viable candidate. We have also used the Hubble Space Telescope to search for stars associated with the H I and find none down to an I-band surface brightness limit of 31.1 ± 0.2 mag arcsec-2.
AB - Many observations indicate that dark matter dominates the extragalactic universe, yet no totally dark structure of galactic proportions has ever been convincingly identified. Previously, we have suggested that VIRGOHI 21, a 21 cm source we found in the Virgo Cluster using Jodrell Bank, was a possible 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 VERGOHI 21 in the neutral hydrogen line and find what could be a dark, edge-on, spinning disk with the mass and diameter of a typical spiral galaxy. Moreover, VIRGOHI 21 has unquestionably been involved in an interaction with NGC 4254, a luminous spiral with an odd one-armed morphology, but lacking the massive interactor normally linked with such a feature. Numerical models of NGC 4254 call for a close interaction ∼108 yr ago with a perturber of ∼1011 M⊙. This we take as additional evidence for the massive nature of VERGOHI 21, as there does not appear to be any other viable candidate. We have also used the Hubble Space Telescope to search for stars associated with the H I and find none down to an I-band surface brightness limit of 31.1 ± 0.2 mag arcsec-2.
KW - Dark matter
KW - Galaxies: individual (VIRGOHI 21)
KW - Radio lines: galaxies
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U2 - 10.1086/520620
DO - 10.1086/520620
M3 - Article
AN - SCOPUS:40249113037
SN - 0004-637X
VL - 670
SP - 1056
EP - 1064
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
ER -