Current PhD Thesis Fellows

#Claire Guépin

Born in Tours in the Loire Valley, I moved to Paris in 2009 after graduating with a Baccalauréat in science. I studied mathematics and physics at the Lycée Henri IV, and had the chance in 2012 to join the Ecole Polytechnique of Palaiseau. After graduating from the Ecole Polytechnique with a master’s degree in astrophysics in 2016, I started a PhD at the Institut d’Astrophysique de Paris. I am currently supported by a fellowship from the CFM Foundation for Research and by the Labex ILP.

Under the supervision of Kumiko Kotera, I am studying the most energetic phenomena of our universe by using a multi-messenger approach. The new generation of telescopes and detectors are reaching sensitivities and temporal resolutions that allow to detect transient phenomena with different messengers, such as photons at various wavelengths, but also cosmic-rays (protons and heavier nuclei), neutrinos and gravitational waves. Within this very exiting context, my work consists of modeling analytically and with numerical simulations the propagation and interaction of particles accelerated in very energetic environnements, such as relativistic jets, shocks or pulsar magnetospheres, and to deduce the subsequent observable multi-messenger signals. So far, I focused on the most energetic messengers, namely ultra-high-energy cosmic rays and high energy neutrinos.

Our first project was dedicated to an analytical study of various transient phenomena, exploring the detectability of neutrino flares associated with photon flares. This general study allows to point the most promising sources for transient neutrino emission and thus for multi-messenger studies. In our second project, we focused on one particularly promising category of sources, tidal disruptions by massive black holes, and evaluated their signatures in ultra-high energy cosmic rays and high-energy neutrinos. For the purpose of this study, we developed a code allowing to simulate the propagation and interaction of ultra-high energy cosmic rays in any type of radiative background. Third, we are exploring two scenarii involving pulsars as cosmic-ray accelerators, exploring on the one hand their ability to accelerate protons, and on the other hand their multi-wavelength signatures in the galactic center region.

I am also involved in two observational projects, focusing on the detection of ultra-high-energy cosmic rays and of a new category of very-high-energy neutrinos, which have not been detected yet. They are characterised by energies even higher than the energies of the neutrinos detected by the IceCube experiment. These two projects, namely GRAND (Giant Radio Array for Neutrino Detection) and POEMMA (Probe Of Extreme Multi-Messenger Astrophysics), focus on the same scientific goals but plan to achieve these with different observational techniques. In order to detect indirectly ultra-high-energy cosmic rays and very-high-energy neutrinos from the signals they produce when interacting with the earth and the atmosphere, GRAND plans to build several gigantic arrays, to detect radio signals, whereas POEMMA plans to send two satellite to space, to detect fluorescence and Cherenkov signals.

Contact: claire.guepin[at]