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A New Monitor for Cosmic Rays in the Solar System: Inverse-Compton Emission from Cosmic-Ray Electrons Scattering with Sunlight

A New Monitor for Cosmic Rays in the Solar System: Inverse-Compton Emission from Cosmic-Ray Electrons Scattering with Sunlight


How well do we understand charged particle propagation in the solar system? This is an important topic for both astrophysics and space weather. Unfortunately, we still lack a fully predictive theory to this problem; a major challenge to this is the lack of cosmic-ray (CR) measurement throughout the solar system, as most data are measured locally on Earth.

I propose to overcome this hurdle in my SolarIC project by using the solar inverse-Compton (IC) emission—produced by CR electrons scattering with Sunlight—as a remote probe for CR distribution throughout the solar system. I will achieve this through three main results. First, I will detect and analyze the solar IC emission with Fermi-LAT data to study its morphology and time dependence. Second, I will calculate the theoretical prediction of the solar IC emission for both GeV and MeV regimes, utilizing state-of-the-art CR simulations. This will be a theoretical foundation for interpreting the data. And for the first time, I will compute the polarization signatures of solar IC emission. Third, building on the previous two results, I will constrain and test contemporary models of CR propagation in the solar system through cross correlation of the Fermi-LAT data with the theory prediction. I will also perform a mock tomographic analysis of the solar IC emission, utilizing the polarization signature. This will be an important and novel prediction for the proposed future MeV space gamma-ray telescopes, such as e-ASTROGAM.

Through my SolarIC project, I will demonstrate that solar IC emission can be used to provide valuable data and constraints on CR distribution in the solar system. This will be an important step leading to a better understanding of charged-particle propagation in the solar system, which will have significant impacts on many astrophysics disciplines including solar physics, cosmic-ray physics, neutrino astrophysics, and dark matter searches.
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Spui 21
1012wx Amsterdam


Activity type

Higher or Secondary Education Establishments

EU Contribution

€ 175 572,48

Project information

Grant agreement ID: 844664


Grant agreement signed

  • Start date

    1 September 2019

  • End date

    31 August 2021

Funded under:


  • Overall budget:

    € 175 572,48

  • EU contribution

    € 175 572,48

Coordinated by: