Scientists are very passionate about finding dark matter, but in a place as big as the universe, it's hard to know where to look. However, a gas giant like Jupiter could serve as a scientific window into finding the elusive dark matter — providing a clue to of the greatest ongoing mysteries in physics, according to a pair of recent studies shared on a preprint server.
Jupiter could serve as a colossal dark matter detector
Dark matter interacts is responsible for holding galaxies together — but precisely how it does this is ambiguous. Popular theories consider dark matter as a sort of particle, too small or weak in its interaction to be observed with ease. Collider and particle accelerator experiments have smashed subatomic particles together — with the aim of observing unexpected quantities of energy missing from the collision — which could hint at the presence of an unknown particle, like dark matter. But nothing of the kind has yet been witnessed.
However, dark matter should also exist naturally, and might be pulled into large gravity wells — like the sun, the Earth, or Jupiter. On a long enough timeline, dark matter could accumulate inside of a planet or star until the density is sufficient for one dark matter particle to collide with another in an event of mutual annihilation. And, even if we can't see dark matter directly, we should be able to observe the results of such a cataclysmic collision — which would generate high-energy radiation called gamma rays.
And in 2008, NASA's Fermi Gamma-ray Telescope was launched atop a Delta II rocket to search the evening sky for sources of gamma rays. Researchers Tim Linden (of Stockholm) and Rebecca Leane (of Stanford) used the telescope to investigate Jupiter, and released the first-ever analysis of the gas giant's gamma-ray activity. The aim was to detect evidence of excess gamma rays resulting from the mutual annihilation of dark matter particles inside Jupiter.
The size and temperature of Jupiter make it an ideal candidate for detecting dark matter, "[b]ecause Jupiter has a large surface area compared to other solar system planets, it can capture more dark matter," said Leane, in a Phys.org report. "You might then wonder why not just use the even bigger (and very close by) sun. Well, the second advantage is that because Jupiter has a cooler core than the sun, it gives the dark matter particles less of a thermal kick."
"This in part can stop lighter dark matter from evaporating out of Jupiter, which would have evaporated out of the sun," explained Leane.
New telescopes could spot evidence of dark matter in Jupiter
Sadly, Leane and Linden's first study of Jupiter found no signs of dark matter. But they did observe a tantalizing gamma-ray excess at low energy levels, the study of which calls for more advanced tools. "We are really stretching Fermi's limits to analyze such low-energy gammas," said Leane, in the Phys.org report. "Looking forward, it will be interesting to see if upcoming MeV gamma-ray telescopes such as AMEGO and e-ASTROGAM find any Jovian gamma rays, especially at the lower end of our analysis, where Fermi's performance suffers."
"Maybe Jupiter still has some secrets to share."
The AMEGO and e-ASTROGRAM telescopes are still only in their preliminary conceptual stages, but they could be what the astronomer calls for to detect dark matter. Jupiter might still be hiding the secrets of dark matter, and if it's found it could also help shed light on the suspected existence of a new kind of dark energy — hypothesized to explain a schism in theories about universal expansion. This is only speculation, but the abundance of unknowns in the evolution of the universe seems poised for a breakthrough.