"A Novel Theory of Particle Acceleration at Shocks"
Please join us for the Physics Department virtual colloquium! There will be a 15 minute zoom social period starting at 12:15 EST, followed by the talk at 12:30 EST. Zoom links will be sent via email.
Diffusive shock acceleration (DSA) is a prominent example of Fermi energization mechanism involved in the origin of Galactic cosmic rays and in producing the multi- wavelength emission in astrophysical systems such as novae, supernova remnants, and galaxy clusters. I outline how ab-initio kinetic simulations of non-relativistic shocks help unravel the very nature of this process. In particular, I discuss the tension between the standard theory of efficient DSA and the steep spectra inferred from observations, stressing the need to go beyond the canonical prediction that strong shocks produce particles with energy spectrum ~E-2, or harder. A revised theory of DSA is presented, in which properly accounting for the backreaction of accelerated particles and self- generated magnetic fields resolves such a tension.