Dense dark matter clumps link three strange objects across the universe
A tiny object half a universe away, a scar in a stream of stars circling the Milky Way, and an unusual star cluster in a nearby satellite galaxy may not seem related at first glance. Yet a new study argues they could all trace back to the same kind of invisible structure. This structure is built from a more active version of dark matter than physicists usually assume. That idea matters because dark matter is not a side note in cosmic history. It makes up about 85% of the universe’s matter. However, no one has seen it directly. Scientists infer its presence from gravity, from the way galaxies rotate, how galaxy clusters behave, and how light bends on its way to Earth. For years, the standard picture has treated dark matter as cold and collisionless. In that view, its particles drift through one another without much fuss. The model works well on large scales. But some smaller, denser structures have kept standing out as awkward exceptions. A team led by UC Riverside physicist Hai-Bo Yu …
