Search for Dark Matter Ionization on the Night Side of Jupiter with Cassini

We present a new search for dark matter (DM) using planetary atmospheres. We point out that annihilating DM in planets can produce ionizing radiation, which can lead to excess production of ionospheric H_{3}^{+}. We apply this search strategy to the night side of Jupiter near the equator. The night side has zero solar irradiation, and low latitudes are sufficiently far from ionizing auroras, leading to a low-background search. We use Cassini data on ionospheric H_{3}^{+} emission collected three hours either side of Jovian midnight, during its flyby in 2000, and set novel constraints on the DM-nucleon scattering cross section down to about 10^{-38}  cm^{2}. We also highlight that DM atmospheric ionization may be detected in Jovian exoplanets using future high-precision measurements of planetary spectra.

First Analysis of Jupiter in Gamma Rays and a New Search for Dark Matter

We present the first dedicated γ-ray analysis of Jupiter, using 12 years of data from the Fermi Telescope. We find no robust evidence of γ-ray emission, and set upper limits of ∼10^{-9}  GeV cm^{-2} s^{-1} on the Jovian γ-ray flux. We point out that Jupiter is an advantageous dark matter (DM) target due to its large surface area (compared with other solar system planets), and cool core temperature (compared with the Sun). These properties allow Jupiter to both capture and retain lighter DM, providing a complementary probe of sub-GeV DM. We therefore identify and perform a new search for DM-sourced γ-rays in Jupiter, where DM annihilates to long-lived particles, which can escape the Jovian surface and decay into γ rays. We consequently constrain DM-proton scattering cross sections as low as about 10^{-40}  cm^{2}, showing Jupiter is up to 10 orders of magnitude more sensitive than direct detection. This sensitivity is reached under the assumption that the mediator decay length is sufficient to escape Jupiter, and the equilibrium between DM capture and annihilation; sensitivities can be lower depending on the DM model. Our work motivates follow-up studies with upcoming MeV telescopes such as AMEGO and e-ASTROGAM.