A triplet of 'ghostly' galaxies narrows the hunt for dark matter

Triplet of 'Ghostly' Galaxies Hints at What Dark Matter Is – and Isn't

Astronomers have spotted three faint, nearly invisible galaxies whose behavior offers fresh clues about what dark matter can and cannot be. Because these 'ghostly' systems barely shine yet appear held together by unseen mass, they act as natural probes of competing dark matter models, helping rule out some candidates while keeping others alive.