Since pure dark matter apparently does not have charge but has mass, might it be found in the galaxy's edge as something akin to uncharged black holes? Typically, pure dark matter is invoked as particles. Wouldn't they form aggregations under gravity? Extended (i.e., not particulate) dark matter, analogous to uncollapsed stars where electromagnetism is normally present, seems to me to be ruled out. This leaves conglomerates of dark and charged matter further to the imagination.