“Dark Galaxy” Dis­cov­ered in the Perseus Clus­ter

The galaxy, called Candidate Dark Galaxy-2 (CDG-2), was discovered not by its faint starlight, but by analyzing an unusual collection of globular clusters—dense, ancient groups of stars that typically orbit galaxies. Subsequent studies of observational data from the Hubble Space Telescope and the Euclid mission finally confirmed an extremely faint glow, proving the existence of this hidden galaxy.

"CDG-2 is the first galaxy identified solely by its globular clusters, and it is among the faintest known galaxies surrounded by such clusters," says Francine Marleau of the Institute of Astro- and Particle Physics at the University of Innsbruck. The astrophysicist first discovered the previously unknown galaxy in images taken by the Euclid Space Telescope.

Scientific estimates indicate that up to 99.99% of the galaxy's mass is dark matter, which accounts for about 85% of the matter in the universe. In addition, at least 17% of the Galaxy's visible light comes from its globular clusters—a proportion of this magnitude never before observed.

"This discovery provides clear evidence that galaxies can form within pure dark matter halos, where visible stars are found only in dense, old star clusters," said Dayi (David) Li, a doctoral student in statistics at the University of Toronto and lead author of the study. "Our work opens a new window into understanding galaxy formation and dark matter."

The study underscores the importance of interdisciplinary collaboration combining astrophysics and modern statistical methods to detect the elusive dark galaxies in the Universe.