Milky Way’s lack of major collisions may make detecting dark matter difficult
DOI: 10.1063/PT.5.028838
New Scientist : When a galaxy gets pulled toward a large disk galaxy, tidal forces rip the galaxy apart and cause its stars and dark matter to be dispersed in the large galaxy’s disk. Because those dispersed stars most likely originated in their host galaxy’s bulge, they look different from their new neighbors in the disk. Justin Read of the University of Surrey in the UK and his colleagues looked for the presence of such foreign stars in the Milky Way but found very few. Their paucity means that the Milky Way has not experienced any major collision events, though it has eaten many smaller galaxies. Read’s finding also implies that the amount of dark matter present in the disk around our solar system may be relatively low and thus difficult to detect.