Jupiter’s night glow could be a smoking gun signal for dark matter: ScienceAlert

There’s a lot of matter out there in the Universe that we haven’t been able to find.

And it’s not an insignificant amount either. Roughly 70 to 80 percent of all matter is thought to be a mysterious matter known as dark matter. Normal matter is the minority. That’s all we can detect – all stars, planets, black holes, dust, gas, moons, people.

So where is all this dark matter? Well, we don’t know. But there are ways we can find out, and one of them is right here in the Solar System.

On Jupiter’s night side, interaction with this shadow material could produce an infrared glow high in the atmosphere.

There are charged hydrogen ions called trihydrogen cations (H₃⁺) can be found in abundance. And while there are several cosmic processes that can produce H₃⁺ in the Jovian atmosphere, interaction with dark matter could produce an excess beyond what we would expect to find.

“We point out that dark matter can produce another source of H₃⁺ in planetary atmospheres,” write physicists Carlos Blanco of Princeton University and Stockholm University and Rebecca Leane of the Stanford Linear Accelerator Center (SLAC) National Accelerator Laboratory and Stanford University.

“This will be created if dark matter dissipates and is captured by planets and then annihilates to produce ionizing radiation.”

Although we cannot detect dark matter directly, and although it does not appear to interact with normal matter in ways that we can detect indirectly, there is one way in which it manifests itself. Objects in space appear to move as if under the influence of much greater gravity than is produced by normal matter.

Once we subtract the contribution from normal matter, the remaining gravity is attributed to dark matter. This is how we know something is there and can measure how much is there.

There are many different theoretical candidates for what dark matter could be, and many of these candidates have properties that can be detected in different ways.

One idea is that dark matter destroys itself. When two dark matter particles collide, they rub off each other and create a small burst of heat or light or both.

Blanco and Leane suggest that this destruction could occur high in the planets’ atmospheres, in a layer known as the ionosphere. Dark matter particles are captured by the planet’s gravity and released into the ionosphere, where they threaten mutual destruction.

The best place to look for this process would be Jupiter, the researchers reasoned. It is the largest non-solar body in the Solar System with a relatively cool core, so it would be the most effective locally available dark matter trap.

When the Cassini Saturn probe flew by Jupiter more than two decades ago, it was equipped with an instrument called the Visual and Infrared Mapping Spectrometer (VIMS), which just might have detected the signature of the supposed annihilation of dark matter.

Now it’s not the little puff of radiation from the annihilation itself that we’d expect, but a product of it. This radiation could be ionizing—that is, it releases electrons from atoms in the ionosphere. This results in a positively charged H₃⁺whose infrared glow was detectable with VIMS.

The problem is that there are many ionizing processes active in the solar system. Sunlight can be ionizing. Jupiter has huge, powerful auroras at its poles that produce H₃⁺, also. So Blanco and Leane looked at measurements from Jupiter’s equatorial region at night, three hours to either side of Jovian midnight, where polar influences are minimal and no sunlight can reach the ionosphere.

While no excess of H₃⁺ The results allowed scientists to set constraints on how this particular type of dark matter should behave, providing crucial information for detecting dark matter on other planets outside the Solar System.

“We point out and show for the first time that dark matter can produce ionizing radiation in planetary atmospheres that is detectable through the smoking gun excess of atmospheric trihydrogen cations,” write Blanco and Leane.

“Atmospheric dark matter ionization may be detected in Jovian exoplanets using future high-precision measurements of planetary spectra.”

The research was published in Physical inspection letters.