The Washington Post reports about research on a galaxy called Dragonfly 44 which is believed to contain about the same mass as the Milky Way but is only 1% as bright. The low ratio of luminosity to mass is characteristic of ultra diffuse galaxies (UDGs). The galaxy is believed to lie 101 megaparsecs (329 million light years) away. The researchers offer explanations for the dimness of UDGs:
[...] it may be that UDGs are "failed" galaxies that were prevented from building a normal stellar population, because of extreme feedback from supernovae and young stars (Agertz & Kravtsov 2015; Calura et al. 2015), gas stripping (Fujita 2004; Yozin & Bekki 2015), AGN feedback (Reines et al. 2013), or other effects.
"AGN" is short for active galactic nucleus — where matter falls into a supermassive black hole. The citation is to "Dwarf Galaxies with Optical Signatures of Active Massive Black Holes" (open, DOI: 10.1088/0004-637X/775/2/116) (DX).
Previously: Huge Population of "Ultra-Dark Galaxies" Discovered
(Score: 1, Informative) by Anonymous Coward on Friday August 26 2016, @04:29PM
AGN is a preferred term because it is much less laden with theoretical assumptions. It simply describes what people see.
(Score: 2) by martyb on Saturday August 27 2016, @01:03AM
You are correct; story updated. Thanks!
Wit is intellect, dancing.