American astrophysicists have proposed using exoplanets to detect dark matter and elucidate the features of its distribution in our Galaxy. They suggested that dark matter raises the temperature of exoplanets, and this parameter can be measured by NASA's James Webb Space Infrared Telescope, which is scheduled to launch in October this year. The article was published in the journal Physical Review Letters.
The model of the distribution of matter in the Universe assumes that galaxies are located inside spherical halos of dark matter, the density of which increases as it approaches the center. If it were not for it, stars from rapidly rotating galaxies would simply fly into outer space. The composition and nature of dark matter is currently unknown, and scientists are trying to come up with ways to identify it.
Astrophysicists Rebecca Leane of Stanford University's SLAC National Accelerator Laboratory and Yuri Smirnov of Ohio State University believe exoplanets can be used as dark matter detectors. According to scientists, when the gravity of exoplanets captures particles of dark matter, they descend into the cores of the planets, where they annihilate with the release of heat, which leads to an increase in the temperature of the planets. And this heating, the authors believe, can be measured using the James Webb Space Telescope.
But not any planets are suitable for this, but only large exoplanets from the "superjupiter" class or substellar objects such as brown dwarfs, the mass of which is tens of times larger than Jupiter and in which thermonuclear reactions have already ended. One of the advantages of using such objects as dark matter detectors is that they do not have nuclear fusion like stars, so they emit less background heat, which makes it difficult to detect a dark matter signal.
Also, as candidates, the researchers suggest distant rogue exoplanets that do not revolve around parent stars. The lack of radiation from the star reduces the interference that obscures the signal from dark matter.
Since tens of thousands of suitable exoplanets are expected to be discovered in the next five years, the researchers hope that their proposed method will confirm or deny the presence of dark matter particles with a mass greater than that of an electron inside the Galaxy.
"We believe that there must be about 300 billion exoplanets waiting to be discovered. Even the discovery and study of a small number of them can give us a lot of information about dark matter, which we now know nothing about," - quoted in a press release from the State University Ohio words by Yuri Smirnov, Research Fellow at the University's Center for Cosmology and Astronomical Particle Physics.
"If exoplanets have anomalous heating associated with dark matter, we can capture it," the scientist adds.
And if the density of dark matter does increase towards the center of our Galaxy, as the theory predicts, then the closer the planets are to the center of the Milky Way, the more their temperature should rise.
"If we found something like that, it would be amazing. It is clear that we would find dark matter," says Smirnov.
At the moment, astronomers have identified more than 4300 exoplanets, another 5695 candidates are in the confirmation stage. The European Space Agency's Gaia space observatory is expected to identify several tens of thousands more exoplanet candidates in the next few years.