New Insights on the Origin of Cosmic Rays

Damiano Caprioli (University of Chicago) - March 19, 2017 at 12:10 pm

I present the results of large kinetic (particle-in-cells) plasma simulations of particle acceleration at non-relativistic collisionless shocks, which allow a first-principles investigation of diffusive acceleration at the blast waves of supernova remnants, the most prominent sources of Galactic cosmic rays (CRs). Ion acceleration efficiency and magnetic field amplification are obtained as a function of the shock properties and compared with theoretical predictions, multi-wavelength observations of individual remnants, and in-situ measurements at heliospheric shocks. Moreover, I outline an original mechanism (the ``espresso mechanism'') for the acceleration of nuclei up to ~10^20eV in the relativistic jets of powerful active galactic nuclei. The combination of the ``supernova-remnant paradigm'' for the origin of Galactic CRs and the ``espresso'' mechanism provides a unified description of the spectrum and the chemical composition of CRs over more than 11 orders of magnitude in energy.

The seminar will be held in 131A Campbell Hall.

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