Speaker
Description
Identifying the accelerators of Galactic cosmic ray (CR) protons with energies up to a few PeV remains a theoretical and observational challenge. Supernova remnants (SNRs) represent strong candidates because they provide sufficient energetics to reproduce the CR flux observed at Earth. Moreover, their strong forward shocks provide an efficient means of accelerating particles: diffusive shock acceleration (DSA). However, it remains unclear whether SNRs can accelerate particles to PeV energies, particularly after the very early stages of their evolution. This uncertainty has prompted searches for other source classes and necessitates comprehensive theoretical modeling of the maximum proton energy accelerated by an arbitrary shock. In this talk I will review the current theory of DSA, and introduce a semi-analytic formalism based on kinetic simulations that accounts for the complex interplay between particle acceleration, magnetic field amplification, and shock evolution. I will use this formalism to parameterize the conditions under which SNRs can be PeVatrons, and to make generalized predictions for the maximum energy accelerated by shock-powered phenomena.
