Galaxy Devoid of Dark Matter Baffles Scientists
- Editor OGN Daily
- May 2
- 2 min read
"No existing galaxy formation model within our standard cosmological paradigm can currently explain how this galaxy came to be."
Dark matter, the invisible substance astronomers believe dominates the universe, provides the gravitational scaffolding for galaxies to assemble and grow. Dark matter constitutes over 80 percent of all matter in the universe, yet it remains unseen by scientists. Its existence is inferred because, without it, the behavior of stars, planets, and galaxies would be inexplicable.
So, discovering a galaxy without dark matter is indeed perplexing, like finding a shadow without a source. Yet, over the past decade, several such sightings have been reported - all of them so-called "ultra-diffuse galaxies," which are about the size of our own Milky Way but remarkably sparse in stars, reports Space.com
FCC 224 - roughly 65 million light-years from Earth - is a dwarf galaxy that boasts a dozen luminous, tightly bound clusters of stars. That's an unusually rich population for its size, typically seen in larger, dark-matter rich galaxies - yet appears to lack the enigmatic substance. It also occupies a distinctly different cosmic neighborhood than other galaxies that are deficient in dark matter, suggesting such objects might not be isolated flukes but actually represent a more common, previously unrecognized class of dwarf galaxies, according to two complementary papers published last month.
FCC 224 is part of a growing population of “ghost galaxies” that seem to lack the invisible glue that binds the universe together, says DailyGalaxy. "No existing galaxy formation model within our standard cosmological paradigm can currently explain how this galaxy came to be," says Maria Buzzo, a doctoral candidate in astrophysics at the Swinburne University of Technology in Australia who led one of the new studies.
Even though it's a bit of a head-scratcher, "FCC 224 serves as a crucial data point in our effort to identify and study other dark-matter-deficient galaxies," says Buzzo. "By expanding the sample size, we can refine our understanding of these rare galaxies and of the role of dark matter in dwarf galaxy formation."
