Satellite Galaxies of the Milky Way Help Test Dark Matter Theory
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Satellite galaxies of the Milky Way help test dark matter theory:
A research team led by physicists at the University of California, Riverside, reports tiny satellite galaxies of the Milky Way can be used to test fundamental properties of "dark matter"-nonluminous material thought to constitute 85% of matter in the universe.
Using sophisticated simulations, the researchers show a theory called self-interacting dark matter, or SIDM, can compellingly explain diverse dark matter distributions in Draco and Fornax, two of the Milky Way's more than 50 discovered satellite galaxies.
The prevailing dark matter theory, called Cold Dark Matter, or CDM, explains much of the universe, including how structures emerge in it. But a long-standing challenge for CDM has been to explain the diverse dark matter distributions in galaxies.
The researchers, led by UC Riverside's Hai-Bo Yu and Laura V. Sales, studied the evolution of SIDM "subhalos" in the Milky Way "tidal field"-the gradient in the gravitational field of the Milky Way that a satellite galaxy feels in the form of a tidal force. Subhalos are dark matter clumps that host the satellite galaxies.
"We found SIDM can produce diverse dark matter distributions in the halos of Draco and Fornax, in agreement with observations," said Yu, an associate professor of physics and astronomy and a theoretical physicist with expertise in particle properties of dark matter. "In SIDM, the interaction between the subhalos and the Milky Way's tides leads to more diverse dark matter distributions in the inner regions of subhalos, compared to their CDM counterparts."
[...] "Our challenge was to understand the origin of Draco and Fornax's diverse dark matter distributions in light of these newly measured orbital trajectories," Yu said. "We found SIDM can provide an explanation after taking into both tidal effects and dark matter self-interactions."
Journal Reference
Omid Sameie, Hai-Bo Yu, Laura V. Sales et al. Self-Interacting Dark Matter Subhalos in the Milky Way's Tides, Physical Review Letters (DOI: 10.1103/PhysRevLett.124.141102)
Also at phys.org.
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