<2> Astronomers Think They’ve Spotted a Galaxy That’s 99.9% Dark Matter
<3> A Galaxy Made of 99.9% Dark Matter
CDG-2, a galaxy located approximately 300 million light-years from Earth, has been discovered to be comprised of 99.9% dark matter. This finding, reported by CNN, suggests that CDG-2 may belong to a hypothesized subset of low surface brightness galaxies called “dark galaxies,” which are believed to contain few or no stars.
<4> The Existence of Dark Galaxies
There is no strict definition of dark galaxies, but their existence is predicted by dark matter theories and cosmological simulations. According to Dayi Li, a post-doctoral astrophysics/statistics fellow at the University of Toronto, “Where exactly do we draw the line in terms of how many stars they should have is still ambiguous, because not everything in astronomy is as clear-cut as we like.”
<5> Observing CDG-2
To observe CDG-2, researchers used data from three telescopes: the Hubble Space Telescope, the European Space Agency’s Euclid space observatory, and the Subaru Telescope in Hawaii. They employed a novel approach that