Unraveling Particle Acceleration and the Nonthermal Universe

Interpreting observations of extreme astrophysical phenomena requires a detailed understanding of particle acceleration in astrophysical environments. These accelerated particles, known as cosmic rays, approximately follow a power-law distribution spanning more than ten orders of magnitude in energy, produce observable nonthermal emission that extends from radio to gamma rays, and are a source of cosmic neutrinos. In the standard picture, supernova remnants and other astrophysical shocks accelerate Galactic cosmic rays via diffusive shock acceleration. However, both the multiwavelength emission from supernova remnants and the population of Galactic cosmic rays detected at Earth reveal discrepancies between this standard theory and observations. In this seminar I will review the current paradigm of shock acceleration and present a fast, multi-zone modeling framework that self-consistently incorporates findings from state-of-the-art kinetic simulations. I will show how this model can resolve key tensions between theory and observations and make predictions for multi-messenger observations. In particular, I will apply this model to a variety of astrophysical objects, including supernova remnants, novae, and winds launched by active galactic nuclei.