New turbulent acceleration mechanisms of cosmic rays from first principles

Cosmic ray (CR) acceleration plays a key role in connecting high-energy electromagnetic radiation and neutrinos in multi-messenger astronomy. Recent gamma-ray and neutrino observations suggest turbulent acceleration as an efficient mechanism accounting for the generation of CRs. However, the traditional theory of turbulent acceleration suffers a long-standing problem in efficiently confining and energizing particles. I report our recent findings on two new acceleration mechanisms identified with the state-of-the-art particle-in-cell (PIC) simulations. PIC simulations can track the microscopic kinetic dynamics of individual particles while computing the collective properties of the plasma, providing a powerful framework for studying these mechanisms. This dual capability makes PIC a powerful tool for studying CR acceleration processes by helping to resolve the limitations of traditional turbulent acceleration models. These findings will bring new insight into the century-old problem of CR origin and have important implications on searching for the correlations of high-energy neutrinos and ultra-high energy cosmic rays.