Dark galaxy: Difference between revisions
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A '''dark galaxy''' is a hypothetical [[galaxy]]-sized object containing very few or no [[star]]s (hence 'dark'), |
A '''dark galaxy''' is a hypothetical [[galaxy]]-sized object containing very few or no [[star]]s (hence 'dark'), held together by [[dark matter]]. It may also contain [[gas]] and [[cosmic dust|dust]]. Although there are some potential candidates, the existence of a dark galaxy has not been confirmed to date.<ref name ="newscientist">{{cite web |url=http://space.newscientist.com/article/dn12100-dark-galaxy-continues-to-puzzle-astronomers.html |title=Dark galaxy' continues to puzzle astronomers |accessdate=2008-02-26 |publisher=[[New Scientist]]|author=Stuart Clark}}</ref> |
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==Candidates== |
==Candidates== |
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Revision as of 21:48, 18 October 2010
A dark galaxy is a hypothetical galaxy-sized object containing very few or no stars (hence 'dark'), held together by dark matter. It may also contain gas and dust. Although there are some potential candidates, the existence of a dark galaxy has not been confirmed to date.[1]
Candidates
HE0450-2958
HE0450-2958 is an unusual quasar as no host galaxy was detected around it.[2] It has been suggested that this may be a dark galaxy in which a quasar has become active. However subsequent observations revealed that a normal host galaxy is probably present.[3]
VIRGOHI21
The discovery of VIRGOHI21 was announced in February 2005, and it was the first good candidate for a true dark galaxy.[1][4][5][6] It was found by looking for the 21cm-wavelength radio waves emitted by hydrogen (HI). Its dynamics are apparently inconsistent with the predictions of the MOND theory.[7] Some researchers have since discounted the possibility of VIRGOHI21 being a dark galaxy, and believe it is more likely a "tidal tail" of nearby galaxy NGC 4254, which is experiencing gravitational perturbations as it enters the Virgo cluster.[8]
See also
References
- ^ a b Stuart Clark. "Dark galaxy' continues to puzzle astronomers". New Scientist. Retrieved 2008-02-26.
- ^ Magain, P. et al. (2005), Discovery of a bright quasar without a massive host galaxy, Nature, 437, 381
- ^ Merritt, D. et al. (2005), The nature of the HE0450-2958 System, arXiv:astro-ph/0511315
- ^ Clark, Stuart (2005-02-23). "Astronomers claim first 'dark galaxy' find". NewScientist.com news service. Retrieved 2006-10-26.
- ^ Shiga, David (2005-02-26). "Ghostly Galaxy: Massive, dark cloud intrigues scientists". Science News Online. 167 (9). Society for Science &: 131. doi:10.2307/4015891. JSTOR 10.2307/4015891. Retrieved 2008-09-14.
- ^ Britt, Roy (2005-02-23). "First Invisible Galaxy Discovered in Cosmology Breakthrough". Space.com.
- ^ Funkhouser, Scott (2005). "Testing MOND with VirgoHI21". Monthly Notices of the Royal Astronomical Society. 364: 237. doi:10.1111/j.1365-2966.2005.09565.x. Retrieved 2006-10-26.
- ^ Haynes, Martha P.; Giovanelli, Riccardo; Kent, Brian R. (2007). "NGC 4254: An Act of Harassment Uncovered by the Arecibo Legacy Fast ALFA Survey". Astrophysical Journal. 665 (1): L19–22. doi:10.1086/521188.
{{cite journal}}: CS1 maint: multiple names: authors list (link)
- Battersby, Stephen (2003-10-20). "Astronomers find first 'dark galaxy'". New Scientist.
External links
- Universe Today, Some Galaxies Are Made Almost Entirely of Dark Matter
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