Théorie

Neutrinos are elementary massive particles with mixings. They can change flavor while propagating. Weakly interacting, neutrinos tell us about the primordial Universe and dense environments, such as exploding stars (core-collapse supernovae) or binary compact objects (neutron star-neutron star, black hole-neutron star). Such neutrinos undergo unexpected flavor phenomena and can be unique probes for new physics.

Highly magnetized environments around compact astrophysical sources (black holes, neutron stars) and their relativistic outflows provide exquisite conditions for accelerating charged particles to very high energies (TeV to PeV and beyond; VHE) and producing multimessenger signals (e.g. photons and neutrinos). Indeed, the pervasive turbulence can ensure efficient stochastic particle acceleration, while the ambient backgrounds provide ideal targets for radiative and hadronic interactions.

The immediate vicinity of black holes provides exquisite conditions for accelerating particles to extremely high energies, up to PeV and beyond. One likely mechanism is via the collisionless plasma turbulence that is expected in the black hole environment, and whose random electromagnetic fields promote efficient stochastic particle acceleration (diffusion in energy space). Accelerated particles add viscosity to the flow, and therefore damp the turbulence that feeds them, giving rise to an interesting nonlinear interaction between particles and electromagnetic fields.