Using Jupiter as a Dark Matter Detector

The nature of dark matter has been a hotly debated topic for decades. If it’s a heavy, slow moving particle then it’s just possible that neutrinos may be emitted during interactions with normal matter. A new paper proposes that Jupiter may be the place to watch this happen. It has enough gravity to capture dark matter particles which may be detectable using a water Cherenkov detector. The researchers suggest using a water Cherenkov detector to watch for excess neutrinos coming from the direction of Jupiter with energies between 100 MeV and 5 GeV.

Jupiter is the largest planet in the solar system, large enough to swallow up all the planets and have a little room to spare. It’s composed mainly of hydrogen and helium and  is devoid of a solid surface. Of all the planets, Jupiter has a powerful magnetic field and a strong gravitational field. It’s gravitational field is so powerful that, over the years, it has attracted, and even destroyed comets like Shoemaker-Levy 9 back in 1994. Of all the features visible in the planet’s atmosphere, the giant storm known as the Great Red Spot is by far the most prominent. 

Image of Jupiter taken by NASA’s James Webb Space Telescope’s NIRCam (Near-Infrared Camera) in July 2022 displays striking features of the largest planet in the solar system in infrared light, with brightness indicating high altitudes. One of these features is a jet stream within the large bright band just above Jupiter’s equator, which was the focus of this study. (Credit: NASA, ESA, CSA, STScI, R. Hueso (University of the Basque Country), I. de Pater (University of California, Berkeley), T. Fouchet (Observatory of Paris), L. Fletcher (University of Leicester), M. Wong (University of California, Berkeley), J. DePasquale (STScI))

Planets in the solar system would, until now, be the last place to go hunting for dark matter. This mysterious stuff is invisible to all normal detection methods but is thought to make up 27% of the universe, outweighing visible matter at 5% (the majority of remainder made up of dark energy.) As its name suggests, dark matter doesn’t emit, absorb or reflect light making it hard to observe. It’s existence has been inferred from the gravitational effects on galaxies, galaxy clusters and the largest scale structures of the universe. Despite its prominence in the universe, the nature of it remains largely unknown. 

Researchers are making progress mapping dark matter, but they don’t know what it is. This is a 3D density map of dark matter in the local universe, with the Milky Way marked by an X. Dots are galaxies, and the arrows indicate the directions of motion derived from the reconstructed gravitational potential of dark matter. Image Credit: Hong et al., doi: 10.3847/1538-4357/abf040.

Dark matter is measured in GeV because this is a standard method in high energy physics to express the mass of particles. Until recently attempts to detect dark matter have relied upon experiments where dark matter is scattered with electrons, protons or neutrons in a detector. The interactions cause energy transfers which then reveal he presence of dark matter. 

A view of the Large Underground Xenon (LUX) dark matter detector. Shown are photomultiplier tubes that can ferret out single photons of light. Signals from these photons told physicists that they had not yet found Weakly Interacting Massive Particles (WIMPs) Credit: Matthew Kapust / South Dakota Science and Technology Authority

In a paper by Sandra Robles from Kings College London and Stephan Meighen-Berger from the University of Melbourne, they propose and calculate the level of annihilating dark matter neutrinos within Jupiter and whether they could be detected using existing neutrino observatories. The team also propose a way to use of water Cherenkov detectors which are designed to detect high-energy particles such as neutrinos or cosmic rays. This is achieved by capturing Cherenkov radiation emitted while they travel through water. To give context to the process, the radiation is optical and occurs when a charged particle moves through a medium like water producing a faint flash of blue light. 

The team suggest Jupiter is an ideal location to hunt for dark matter using Cherenkov radiation detectors. It’s low core temperature and significant gravitational attraction will mean it could capture dark matter and retain it.  The presence of neutrinos in the direction of Jupiter reveals the capture and annihilation of dark matter. A similar technique is used by observing the Sun. 

Source : Extending the Dark Matter Reach of Water Cherenkov Detectors using Jupiter

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