A team of astronomers may have discovered a galaxy invisible to our telescopes. This finding could shed light on a decades-old mystery.
Overview of the high-velocity gas cloud AC-I.
Credit: Science Advances (2025). DOI: 10.1126/sciadv.ads4057
Chinese researchers analyzed data from two major telescopes. Their attention focused on a fast-moving gas cloud at the edge of the Milky Way. This cloud, named AC-I Complex, contains a peculiar gas concentration called G185.0-11.5.
High-velocity clouds are generally considered remnants of galaxies torn apart by gravitational forces. They are often composed of matter ejected during supernova explosions or stripped from other galaxies. However, the case of G185.0-11.5 appears different.
Observations reveal that G185.0-11.5 is located about 900,000 light-years from Earth. It shows a rotational structure but no visible stars. This characteristic aligns with the hypothesis of a dark galaxy, primarily composed of dark matter.
Measurements indicate that unexplained matter in G185.0-11.5 is 21 times more abundant than normal matter. This disproportion strongly suggests the presence of dark matter. Researchers believe this matter influences the cloud's rotation.
Comparison between observation and model for the gas concentration.
Credit: Science Advances (2025). DOI: 10.1126/sciadv.ads4057 The proximity of G185.0-11.5 allows its study by other ground-based telescopes. If this gas concentration proves to be a dark galaxy, it could offer a unique opportunity to study dark matter directly. Upcoming observations will be decisive.
This discovery, published in
Science Advances, opens new perspectives for understanding the nature of dark galaxies. It also highlights the importance of international collaborations in astronomy.
What is a dark galaxy?
A dark galaxy is a cosmic structure primarily composed of dark matter, an invisible substance that neither emits nor absorbs light. Unlike traditional galaxies, they contain few or no stars, making them extremely difficult to detect.
Dark matter represents about 85% of the matter in the Universe. Its existence is inferred from the gravitational effects it exerts on galaxies and galaxy clusters. Dark galaxies could be relics from the early Universe, offering clues about the formation of cosmic structures.
The potential discovery of G185.0-11.5 as a dark galaxy would be a major breakthrough. It would allow scientists to study dark matter directly in a galactic context, which was previously impossible.
Future research on dark galaxies could revolutionize our understanding of the Universe. It might also help solve other cosmological mysteries, such as the nature of dark matter itself.