These oddball galaxies are missing their dark matter
A pair of dim, puffy galaxies are devoid of this key cosmic ingredient. Now astronomers using the Hubble Space Telescope say they may know why.
In the cosmic equivalent of a total knock-out punch, two galaxies collided some eight billion years ago and kicked the gas out of each other.
That’s the latest explanation for a cosmic mystery that’s had astronomers scratching their heads since 2018: two dim, puffy galaxies that appear to be completely devoid of dark matter. New observations suggest those galaxies could be part of a string of similarly bizarre objects—the debris from the galactic smashup.
Detailed studies those two galaxies, called DF2 and DF4, had previously revealed that they are inhabited by strange, luminous star clusters. But scientists have been struggling to explain how these galaxies could exist at all, because dark matter—which makes up more than 80 percent
