New Dark Matter Theory Could Solve Cosmic Mysteries

UC Riverside physicist proposes self-interacting dark matter could explain unusual gravitational effects across the universe.

Apr. 14, 2026 at 6:05am

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A bold, abstract painting featuring sweeping geometric arcs, concentric circles, and precise spirals in earthy tones of brown, ochre, and deep blue, conceptually representing the complex interactions and gravitational effects of self-interacting dark matter.A new model of self-interacting dark matter could help solve long-standing cosmic mysteries by explaining unusual gravitational effects observed across the universe.Riverside Today

A study led by UC Riverside physicist Hai-Bo Yu suggests that a new type of self-interacting dark matter (SIDM) could simultaneously explain three astrophysical puzzles in vastly different environments - the powerful magnifying effect of an ultra-dense object in a gravitational lens, a striking spur-and-gap feature in a stellar stream, and the unusual star cluster in a neighboring satellite galaxy of the Milky Way.

Why it matters

The standard model of cold, collisionless dark matter has struggled to explain certain high-density structures observed in the universe. Yu's work on SIDM, where dark matter particles collide and exchange energy, offers a potential solution that could reshape our understanding of the internal structure of dark matter halos.

The details

Yu's study, published in Physical Review Letters, proposes that dense clumps of SIDM - each about a million times the mass of the sun - can account for the unusual gravitational effects observed in gravitational lenses, stellar streams, and satellite galaxies. These SIDM interactions can trigger "gravothermal collapse," forming extremely dense, compact cores that are difficult to reconcile with standard model dark matter.

  • The study was published on April 14, 2026.

The players

Hai-Bo Yu

A professor of physics and astronomy and deputy director of the Center for Experimental Cosmology and Instrumentation at the University of California, Riverside, who led the study on self-interacting dark matter.

University of California, Riverside

A doctoral research university where Yu's study was conducted, known for its groundbreaking exploration of issues critical to Inland Southern California, the state, and communities around the world.

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What they’re saying

“The difference is like a crowd of people who ignore each other versus one where everyone is constantly bumping into one another. In SIDM, these interactions can dramatically reshape the internal structure of dark matter halos. Dark matter that interacts with itself can become dense enough to explain these observations.”

— Hai-Bo Yu, Professor of Physics and Astronomy

What’s next

The research was supported by the John Templeton Foundation and the U.S. Department of Energy, and the findings could lead to further studies on the nature of dark matter and its role in shaping the universe.

The takeaway

This study offers a promising new model of self-interacting dark matter that could help solve long-standing cosmic mysteries, challenging the standard assumptions about the nature of dark matter and its influence on the structure of the universe.