The new theory of dark matter explains two puzzles in astrophysics

Thought to make up 85% of the matter in the universe, dark matter is incomprehensible and its nature is not well understood. While normal objects absorb, reflect, and transmit light, dark matter cannot be seen directly, making it difficult to see. A theory called “self-interacting dark matter,” or SIDM, suggests that dark matter interacts with itself through the dark force, colliding with each other violently. and the other near the center of the galaxy.

Inside published work c The Astrophysical Journal Lettersa research team led by Hai-Bo Yu, a professor of physics and astronomy at the University of California, Riverside, reported that SIDM can explain at the same time two astrophysics puzzles in extreme opposition.

“The first is a dark matter high-density halo in a large elliptical galaxy,” said Yu. “The halo was detected by observing the gravitational force of the crystal, and its density is so high that it is very unlikely in the theory of cold dark matter that it exists. It is difficult to explain by the theory of cold weather.”

The dark matter halo is the half of invisible matter that enters and surrounds a galaxy or cluster of galaxies. Model of gravity that occurs when light travels through the universe from distant galaxies to larger objects. The cold dark matter, or CDM, model/theory states that the components of dark matter are incompatible. As their name suggests, ultra-diffuse galaxies have very low luminosity and the distribution of their stars and gas is spread out.

Yu was joined in the study by Ethan Nadler, a postdoctoral associate at the Carnegie Observatories and the University of Southern California, and Daneng Yang, a postdoctoral fellow at UCR.

To show that SIDM can explain two astrophysics puzzles, the team conducted the first high-resolution simulation of the formation of the universe with the strong self-interacting dark matter on large scales. suitable for hard crystal and ultra-diffuse galaxies.

“These self-interactions lead to heat in the halo, which determines the height of the halo in the central regions of the galaxies,” said Nadler. “In other words, some halos have a higher centrality, and others have a lower centrality, compared to their CDM, with information related to the history of the cosmic evolution and the environment of each halo .”

According to the team, two puzzles pose a serious challenge to the traditional CDM model.

“CDM has been challenged to explain these puzzles,” Yang said. “SIDM is undoubtedly the strongest candidate to meet these two opposing passions. There is no other information available in the literature. Now there is a serious problem that may be more complex and lively. things darker than we expected.”

The study also shows the power of studying dark matter through astrophysical studies, with the tool of computer simulations of the structure of the universe.

“We hope our work will encourage more research in this area of ​​successful research,” said Yu. “It will be a unique development at the time to provide the most reliable information in the near future from space probes, including the James Webb Space Telescope and the future Rubin Observatory.”

Since 2009, the work of Yu and collaborators has helped to popularize SIDM in the physics and astrophysics communities.