ASTRONOMY MAGAZINE - Maybe dark matter talks to itself, according to a new proposal, and that might just explain two cosmological mysteries at once.
Dark matter is the name astronomers give to the mysterious substance that makes up the bulk of all matter in the universe. Upwards of 80 percent of the mass of a galaxy exists in the form of this strange, invisible stuff. But despite our inability to directly identify it, we can see the effects it has on its environment, like providing the gravitational glue needed to keep stars in their orbits despite their incredibly rapid rotation around galactic centers.
According to Hai-Bo Yu, a professor of physics and astronomy at the University of California, Riverside and the leader of the research team, they felt that a more complex version of dark matter could explain these two galactic extremes.
“The first is a high-density dark matter halo in a massive elliptical galaxy,” Yu says. “The halo was detected through observations of strong gravitational lensing, and its density is so high that it is extremely unlikely in the prevailing cold dark matter theory. The second is that dark matter halos of ultra-diffuse galaxies have extremely low densities and they are difficult to explain by the cold dark matter theory.”