Low surface brightness galaxy

An image of NGC 45, a low surface brightness spiral galaxy, by GALEX.
UGC 477 is located over 110 million light-years away in the constellation of Pisces.[1]

A low-surface-brightness galaxy, or LSB galaxy, is a diffuse galaxy with a surface brightness that, when viewed from Earth, is at least one magnitude lower than the ambient night sky.

Most LSBs are dwarf galaxies, and most of their baryonic matter is in the form of neutral gaseous hydrogen, rather than stars. They appear to have over 95% of their mass as non-baryonic dark matter. There appears to be little supernova (SN) activity in these galaxies,[citation needed] although LSB galaxy IC 217 hosted 2014cl.[2][3]

Rotation curve measurements indicate an extremely high mass-to-light ratio, meaning that stars and luminous gas contribute only very little to the overall mass balance of an LSB. The centers of LSBs show no large overdensities in stars, unlike e.g. the bulges of normal spiral galaxies. Therefore, they seem to be dark-matter-dominated even in their centers, which makes them excellent laboratories for the study of dark matter.

In comparison to the high-surface-brightness galaxies, LSBs are mainly isolated field galaxies, found in regions devoid of other galaxies. In their past, they had fewer tidal interactions or mergers with other galaxies, which could have triggered enhanced star formation. This is an explanation for the small stellar content.

LSB galaxies were theorized to exist in 1976 by Mike Disney.

  1. ^ "Hiding in the night sky". ESAHubble.org. Retrieved 4 April 2016.
  2. ^ Monnier Ragaigne, D.; van Driel, W.; Schneider, S. E.; Jarrett, T. H.; Balkowski, C. (July 2003). "A search for Low Surface Brightness galaxies in the near-infrared: I. Selection of the sample". Astronomy & Astrophysics. 405 (1): 99–109. arXiv:astro-ph/0304380. Bibcode:2003A&A...405...99M. doi:10.1051/0004-6361:20030585. ISSN 0004-6361.
  3. ^ Gonzalez, L.; Hamuy, M.; Antezana, R.; Cartier, R.; Forster, F.; Carrasco, F.; Pignata, G.; Apostolovski, Y.; Paillas, E.; Varela, S.; Bufano, F.; Olivares, F.; Takats, K.; Catalan, T.; Rivas, C. (August 2014). "Supernova 2014cl in IC 217 = Psn J02160910-1156026". Central Bureau Electronic Telegrams. 3950: 1. Bibcode:2014CBET.3950....1G.