SoylentNews is people
SoylentNews
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.
(Score: 0) by Anonymous Coward on Friday April 17 2020, @12:34AM
That's nonsense. As someone who performs sophisticated simulations of processes in the Earth's atmosphere, I am familiar with their value in science.
For a complex system like the atmosphere or the cosmos, there are a large number of variables that are difficult. perhaps impossible to control for in real world experiments. In a simulation, everything else can be held constant except the one or two variables you want to systematically change to see their impact. It also makes it much easier to study individual processes in isolation, compared to the real world where there are many processes occurring at a single time, making it difficult to isolate the impact of a particular process. The model is insufficient to demonstrate a process or the sensitivity of a process to a particular variable, but the results can be useful in identifying the consequences of a process or of changes in a particular variable. These simulations can provide guidance about what to look for in real world observations that might provide support for a process or the sensitivity of a process to a particular variable. We can then look for correlations in observed data that are consistent with the model simulations. If model simulations don't show sensitivity to a variable or can't replicate a particular process, it can be useful information to avoid conducting experiments that are unlikely to provide useful results.
The simulations don't prove that the process of self-interacting dark matter explains the distribution of dark matter within galaxies. However, the model suggests that the distribution of dark matter within halos is related to whether core collapse occurs. This is something that scientists can look for observation evidence to support. The model provides useful information for developing hypotheses that can be tested observationally.
-- APK is complete garbage