A new study proposes that exoplanets, planets orbiting stars outside our solar system, could be instrumental in the quest to understand dark matter.

With over 5,000 exoplanets identified, scientists are leveraging these distant worlds to deepen our understanding of planetary evolution and the potential for life beyond Earth.

Researchers have been exploring how dark matter, wich accounts for an estimated 85% of the universe’s mass-energy density, might influence exoplanets similar in size to Jupiter over extended periods. Their simulations suggest that dark matter particles could gradually accumulate within the cores of these planets. Despite the fact that dark matter remains undetected in laboratory experiments, its existence is strongly supported by astrophysical observations.

According to Mehrdad Phoroutan-Mehr, a doctoral student in astronomy and physics at the University of California, Riverside, and lead author of the study, “If the dark matter particles are heavy enough and don’t annihilate, they may eventually collapse into a tiny black hole.” He collaborates with Hai-Bo Yu, a professor of physics and astronomy.

“This black hole could then grow and consume the entire planet, turning it into a black hole with the same mass as the original planet. This outcome is only possible under the superheavy non-annihilating dark matter model.”

The superheavy non-annihilating dark matter model posits that dark matter particles possess important mass and do not self-annihilate upon interaction. The research team concentrated on this model to illustrate how these particles could be captured by exoplanets, lose kinetic energy, migrate towards the planet’s core, accumulate, and ultimately collapse into black holes.

“In gaseous exoplanets of various sizes, temperatures, and densities, black holes could form on observable timescales, potentially even generating multiple black holes in a single exoplanet’s lifetime,” Phoroutan-Mehr says.

“These results show how exoplanet surveys could be used to hunt for superheavy dark matter particles, especially in regions hypothesized to be rich in dark matter like our Milky Way’s galactic center.”

Tara Fetherolf, a postdoctoral researcher in the earth and planetary sciences department, also contributed to the study.

Phoroutan-Mehr notes that astronomers have, to date, only detected black holes with masses exceeding that of our sun. He points out that prevailing theories suggest a minimum mass threshold for black hole formation.

“Discovering a black hole with the mass of a planet would be a major breakthrough,” he adds.

“It would support the thesis of our paper and offer an option to the commonly accepted theory that planet-sized black holes could only form in the early universe.”

Phoroutan-Mehr suggests that the limited use of exoplanets in dark matter research stems from a ancient lack of sufficient data.

“But in recent years, our knowledge of exoplanets has expanded dramatically, and several upcoming space missions will provide even more detailed observations,” he says.

“With this growing body of data, exoplanets can be used to test and challenge different dark matter models.”

Phoroutan-Mehr explains that previous dark matter investigations involved observations of objects such as the sun, neutron stars, and white dwarfs, given that different dark matter models predict varying effects on these celestial bodies. as a notable example, certain models propose that dark matter could heat neutron stars.

“So, if we were to observe an old and cold neutron star, it could rule out certain properties of dark matter, since dark matter is theoretically expected to heat them up,” he says.

He adds that the fact that many exoplanets (and Jupiter in our solar system) have not collapsed into black holes can help scientists rule out or refine dark matter models such as the superheavy non-annihilating dark matter model.

“If astronomers were to discover a population of planet-sized black holes, it could offer strong evidence in favor of the superheavy non-annihilating dark matter model,” Phoroutan-Mehr says.

“As we continue to collect more data and examine individual planets in more detail, exoplanets may offer crucial insights into the nature of dark matter.”

Phoroutan-Mehr notes that another possible effect of dark matter on exoplanets-and possibly on planets in our solar system-is that it could heat them or cause them to emit high-energy radiation.

“Today’s instruments aren’t sensitive enough to detect these signals,” he says. “Future telescopes and space missions may be able to pick them up.”

The study appears in Physical Review D.