News Summary

Astronomers have identified a unique galaxy, Candidate Dark Galaxy-2 (CDG-2), which is composed almost entirely of dark matter, with only a scant number of visible stars. This galaxy, located in the Perseus cluster about 300 million light-years away, is notable for its extremely low luminosity and the dominance of dark matter, accounting for 99% of its mass. The discovery was made possible through the combined efforts of NASA’s Hubble Space Telescope and other observatories, which detected faint light around four globular clusters that make up the visible structure of CDG-2. This research provides valuable insights into the nature of dark matter and the formation of galaxies, presenting CDG-2 as a natural laboratory for further studies. The findings illustrate the capabilities of advanced telescopes like Euclid and Subaru in detecting low-surface-brightness galaxies, potentially transforming our understanding of dark matter’s role in the universe.