It turns out, rocky things aren’t the only things that suffer when forced to interact with others.
There is a special kind of galaxy, the ultra-diffuse galaxies, that are rare, hard to find, and appear to simply be groups of stars like those normally found in dwarf galaxies but spread over an unusually large volume of space. In a new paper, led by Jose Benavides and appearing in Nature, researchers use computer models to piece together how these systems might form. It appears that they are literally dwarf galaxies that passed through the dark matter halos of galaxy clusters, and in the process, got spread out and lost the stuff needed to form new stars. According to the models, this only happens to systems with the kind of angular momentum or speed to fling them into the voids outside of the cluster, so if you want to find ultra-diffuse galaxies, look into the empty places where, thanks to dark matter, they are left to die.
Space isn’t kind, y’all. But it does create wonderfully weird things to explore.
MIT press release
“Quiescent ultra-diffuse galaxies in the field originating from backsplash orbits,” José A. Benavides et al., 2021 September 6, Nature Astronomy