Micro-physics of Cosmic-Ray Observables – MiCRO

The transport of cosmic rays (CRs) in our Galaxy is a multidisciplinary topic at the intersection between astroparticles, nuclear physics and plasma astrophysics. More than a century after their discovery, our understanding of the microphysics responsible for CR transport is being seriously challenged by recent direct and indirect high-precision measurements. A self-consistent picture of CR transport should be able to reproduce the wide landscape of CR observables based on first principles, ultimately bringing together the most-advanced plasma-turbulence theories and CR-driven instabilities that provide feedback onto such turbulence and CRs own propagation.

The ANR JCJC project MiCRO bridges for the first time the theoretical and computational gap between the astroparticle and plasma physics communities by exploiting the complementarity of a first-principle plasma-physics approach and efficient CR-phenomenology modelling. MiCRO consists of three work packages handled by the PI, a postdoc hired through this project, and a team of well-recognized experts in all the relevant fields. The project combines analytical techniques and ab-initio massively parallel fluid/kinetic plasma simulations to advance our understanding of turbulence and its nonlinear coupling with CR kinetics. Then, global simulations of CR transport and multi-messenger emission are employed to understand the link between CR microphysics and their observables. Our results will (a) identify which features in the available direct and indirect CR data can be interpreted as compelling evidence for different transport models, and (b) have predictive potential for CR data from current and future observatories. The project will also deliver (c) state-of-the-art open-source numerical tools and (d) a public database of plasma and CR simulations.