Princeton University Astroplasmas Seminar

With the development of multi-messenger astronomy and the detection of astrophysical neutrinos, we are in a golden age of new cosmic ray (CR) measurements and studies. Supernova remnants are believed as the leading candidate for the source of Galactic CRs. Recent observations, however, challenge the well-developed theory of diffusive shock acceleration of CRs in supernova remnants. I will reexamine the assumptions in the standard shock acceleration model and discuss the key missing physics for shocks propagating in the turbulent and inhomogeneous interstellar medium. A more realistic shock acceleration model holds the promise to understand the observational puzzles and the origin of Galactic CRs.