Triplet of 'ghostly' galaxies hints at what dark matter is and isn't
Scientists studying three ultra‑diffuse, faint galaxies have found they contain far less dark matter than expected. The observations, made using telescopes that map stellar motions, suggest that dark matter may be absent or distributed differently in such systems. These findings could refine models of galaxy formation and the role of dark matter, though they do not overturn existing cosmological theory.