http://www.sciencemag.org/news/2020/03/physicists-brawl-over-new-dark-matter-claim

By looking for x-rays coming from the sky between the stars, a team of physicists claims to have ruled out one possible type of dark matter.

For decades, astrophysicists have thought some sort of invisible dark matter must pervade the galaxies and hold them together, although its nature remains a mystery. Now, three physicists claim their observations of empty patches of sky rule out one possible explanation of the strange substance—that it is made out of unusual particles called sterile neutrinos. But others argue the data show no such thing.