Dissipative Dark Matter and the Andromeda Plane of Satellites

December 16, 2014
Andromeda galaxy

"Andromeda Galaxy (with h-alpha)" by Adam Evans. Uploaded by NotFromUtrecht. Licensed under CC BY 2.0 via Wikimedia Commons [link]

In a recent arXiv paper, Prof. Lisa Randall and postdoc Jakub Scholtz investigate a possible explanation for the planar distribution of satellite dwarf galaxies with high dark matter content. They find that the presence of a thin dark disk formed from cooled dissipative dark matter during galactic collisions can result in formation of DDDM-rich tidal dwarf galaxies after galactic mergers. In their simulations, the final dark matter to baryon ratio could reach as high as ~30. Such numbers are in agreement with some of the observed M=L values for the tidal dwarf in the plane around Andromeda galaxy. However, this ratio depends on the size of the region that gets ejected during the merger of the two galaxies. This study does not determine the scale of these patches and further full simulations of galactic mergers containing dark disks have to be performed in order to answer this question. (See arXiv:1412.1839v1)