Astronomers just spotted two galaxies that seem to have almost no dark matter. That’s a big deal because most models say galaxies need dark matter to hold together – without it, they would just fall apart. These galaxies, FCC 224 and FCC 240, live on the edge of the Fornax Cluster, about 60 million light-years away.
Study conducted using ESO's very large telescope
Normally, dark matter acts as this invisible glue, keeping stars from flying off into space. But these two are not following the rules. A team at Yale, led by Maria Luísa Buzzo, dug into the details using the MUSE instrument on the European Southern Observatory’s Very Large Telescope. They posted their findings on arXiv in May 2026.
What really makes FCC 224 and FCC 240 stand out is their low velocity dispersion—that’s a fancy way of saying the stars inside aren’t whipping around as they do in other galaxies. If dark matter were there, you’d expect faster, more chaotic motion. But that’s not happening, which means dark matter’s missing in action.
Evidence supports 'Bullet-Dwarf' hypothesis
The team thinks these galaxies fit with something called the “bullet-dwarf” hypothesis. This idea basically says a high-speed crash between dwarf galaxies can knock out most of a galaxy’s dark matter but leave the stars alone. FCC 224 and FCC 240 also have unusually bright globular clusters, which this theory predicts.
Implications for cosmology
Up until now, astronomers had only found one confirmed pair of nearly dark-matter-free galaxies (NGC 1052-DF2 and NGC 1052-DF4), and those are ultra-diffuse galaxies—big but with hardly any stars. Spotting another pair, especially in a different part of the universe, hints that maybe these oddballs aren’t as rare as we thought.
If more observations back this up, astrophysicists might have to rethink how galaxies evolve. The current picture does not really explain how a galaxy can dump most of its dark matter and still stay intact. So, these two galaxies throw a curveball into our understanding of the universe. We obviously have a lot more to figure out about both dark matter and galaxy formation.
