Have you ever wondered what makes up most of the universe?
A recent study brings us closer to understanding this mystery, focusing on something called dark matter.
This invisible substance is thought to account for about 85% of all matter in the universe, but it’s tricky to study because it doesn’t emit, absorb, or reflect light like the stuff we can see.
Scientists have been puzzling over dark matter for years.
Now, a team led by Professor Hai-Bo Yu from the University of California, Riverside, has come up with a new theory that could explain some of the biggest mysteries about it.
They call it “self-interacting dark matter,” or SIDM. This idea suggests that dark matter particles can interact with each other through a special force, colliding especially in the centers of galaxies.
Published in The Astrophysical Journal Letters, this study shows how SIDM could solve two contrasting astrophysical puzzles.
The first puzzle involves massive elliptical galaxies with high-density dark matter halos, regions of invisible matter surrounding galaxies. These halos were spotted through a phenomenon called gravitational lensing, where light bends around massive objects in space.
The high density of these halos doesn’t fit with the traditional theory of cold dark matter, which assumes that dark matter particles don’t collide.
The second puzzle is about ultra-diffuse galaxies. These galaxies are very faint and spread out, and their dark matter halos have extremely low densities. This is also hard to explain with the traditional theory.
To test their SIDM theory, Yu’s team, including Ethan Nadler and Daneng Yang, ran high-resolution simulations of how cosmic structures form, considering strong interactions between dark matter particles.
These simulations showed that heat transfer within the halo can cause differences in density at the center of galaxies. Some have higher densities, while others have lower, depending on their cosmic history and surroundings.
This discovery challenges the standard cold dark matter paradigm, which has been the main theory for years.
According to the researchers, SIDM offers a more convincing explanation for these two extreme cases. It suggests that dark matter might be more complex and dynamic than previously thought.
The study also highlights the importance of astrophysical observations and computer simulations in understanding dark matter. With upcoming data from telescopes like the James Webb Space Telescope and the Rubin Observatory, the team hopes their work will inspire more research in this exciting field.
Professor Yu and his collaborators have been advocating for the SIDM theory since around 2009. Their work, supported by the John Templeton Foundation and the U.S. Department of Energy, is gaining attention in the worlds of particle physics and astrophysics.
The paper, titled “A Self-interacting Dark Matter Solution to the Extreme Diversity of Low-mass Halo Properties,” is freely available, inviting everyone to explore this groundbreaking research.
This study not only answers long-standing questions but also opens up new avenues for understanding the universe in ways we never imagined.
Source: UC Riverside.
