universetoday.com/articles/a-distant-supercluster-of-galaxies-points-to-self-interacting-dark-matter A Distant Supercluster of Galaxies Points To Self-Interacting Dark Matter
A galaxy cluster called El Gordo, 7 billion light-years out, is too massive and too early to fit standard cosmology. A new simulation suggests dark matter that sometimes collides elastically and sometimes doesn't could explain the mismatch, though the fit depends on numbers still too uncertain to confirm it.
— via Universe Today, Brian Koberlein
