Comparing this to the visible matter of galaxies allows us to map the presence of dark matter. But there are also predictions we can't easily test, such as dark matter filaments. As dark matter clumps together, some of the dark matter should be left behind, forming filaments of dark matter that connect galaxies and clusters of galaxies. There has been some evidence of dark matter filaments. The result is a statistical image of the dark matter filaments between galaxy pairs.

Source: Forbes April 17, 2017 14:02 UTC