Astronomers have discovered more than 5,000 planets orbiting stars beyond our solar system, known as exoplanets.
These worlds are already changing how scientists think about planetary evolution and the possibility of life beyond Earth.
Now, researchers at the University of California, Riverside, suggest exoplanets might also help solve one of the greatest mysteries in physics: the nature of dark matter.
Dark matter is thought to make up about 85% of all matter in the universe.
It cannot be seen directly, but scientists believe it exists because of its gravitational effects on galaxies and cosmic structures.
Despite decades of searching, dark matter has never been detected in a laboratory. But a new study, published in Physical Review D, proposes that exoplanets—especially gas giants like Jupiter—could offer a natural laboratory for uncovering dark matter’s secrets.
According to the research team, dark matter particles may slowly build up inside the cores of giant exoplanets. Over very long timescales, this hidden matter could collapse into tiny black holes.
“If the dark matter particles are heavy enough and don’t annihilate each other, they may eventually collapse into a black hole,” explained Mehrdad Phoroutan-Mehr, the study’s first author and a graduate student in physics and astronomy at UC Riverside.
“This black hole could then grow and consume the entire planet, leaving behind a black hole with the same mass as the original planet.”
This possibility relies on a theory known as the “superheavy non-annihilating dark matter” model. In this framework, dark matter particles are extremely massive and do not destroy one another when they collide.
Instead, they gradually lose energy, sink toward a planet’s center, and pile up until they collapse under their own weight.
In gas giants of different sizes and temperatures, this process could happen on timescales that astronomers might one day observe. In fact, multiple black holes could even form during a single exoplanet’s lifetime.
The idea is striking because, so far, astronomers have only discovered black holes more massive than the sun.
A black hole with the mass of a planet would be unprecedented. “Finding one would be a major breakthrough,” Phoroutan-Mehr said. “It would support our model and offer an alternative to the common theory that planet-sized black holes could only have formed in the early universe.”
Until recently, exoplanets were rarely considered in dark matter research, simply because scientists lacked enough data.
That is quickly changing. With thousands of known exoplanets and more space missions on the way, researchers now have far more opportunities to test dark matter theories using these distant worlds.
Phoroutan-Mehr explained that studying exoplanets adds to the long tradition of using cosmic objects to probe dark matter. For example, previous studies examined how dark matter might heat up neutron stars or affect white dwarfs.
Observing cold neutron stars, for instance, has already helped rule out certain dark matter models.
Similarly, the fact that many exoplanets—including Jupiter in our own solar system—have not collapsed into black holes gives scientists a way to refine or rule out the superheavy non-annihilating model.
Future observations may reveal other clues. Dark matter could heat up planets or even cause them to emit high-energy radiation. While current instruments are not sensitive enough to detect these signals, upcoming telescopes might be able to.
If astronomers eventually detect a population of planet-sized black holes, it would strongly suggest that superheavy dark matter is real. Until then, exoplanets may prove to be one of the most promising tools for unraveling the mystery of the invisible matter shaping our universe.
Source: UC Riverside.
