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Gravitational detection of a low-mass dark satellite galaxy at cosmological distance
- Source :
- Nature, 481(7381), 341-343. Nature Publishing Group
- Publication Year :
- 2012
-
Abstract
- The mass-function of dwarf satellite galaxies that are observed around Local Group galaxies substantially differs from simulations based on cold dark matter: the simulations predict many more dwarf galaxies than are seen. The Local Group, however, may be anomalous in this regard. A massive dark satellite in an early-type lens galaxy at z = 0.222 was recently found using a new method based on gravitational lensing, suggesting that the mass fraction contained in substructure could be higher than is predicted from simulations. The lack of very low mass detections, however, prohibited any constraint on their mass function. Here we report the presence of a 1.9 +/- 0.1 x 10^8 M_sun dark satellite in the Einstein-ring system JVAS B1938+666 at z = 0.881, where M_sun denotes solar mass. This satellite galaxy has a mass similar to the Sagittarius galaxy, which is a satellite of the Milky Way. We determine the logarithmic slope of the mass function for substructure beyond the local Universe to be alpha = 1.1^+0.6_-0.4, with an average mass-fraction of f = 3.3^+3.6_-1.8 %, by combining data on both of these recently discovered galaxies. Our results are consistent with the predictions from cold dark matter simulations at the 95 per cent confidence level, and therefore agree with the view that galaxies formed hierarchically in a Universe composed of cold dark matter.<br />Comment: 25 pages, 7 figures, accepted for publication in Nature (19 January 2012)
- Subjects :
- Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Dwarf galaxy problem
FOS: Physical sciences
Astrophysics
Astrophysics::Cosmology and Extragalactic Astrophysics
LENSES
Satellite galaxy
HALOES
Interacting galaxy
Galaxy rotation curve
Astrophysics::Galaxy Astrophysics
SCALE
Dwarf galaxy
Physics
Multidisciplinary
Astronomy
STATISTICS
EVOLUTION
Dwarf spheroidal galaxy
Dark matter halo
B1938+666
SUBHALOES
MATTER SUBSTRUCTURE
MILKY-WAY
Dark galaxy
Astrophysics - Cosmology and Nongalactic Astrophysics
Subjects
Details
- Language :
- English
- ISSN :
- 00280836
- Volume :
- 481
- Issue :
- 7381
- Database :
- OpenAIRE
- Journal :
- Nature
- Accession number :
- edsair.doi.dedup.....5066a8e24c38b6bedd4b4931c3093aab