University of Maryland
Atlantic Building, Room 2400
4:30 PM Monday, November 7, 2011
Coffee, Tea & Snacks 4:15-4:30 PM

Vladimir Ptuskin
Acceleration of Galactic Cosmic Rays in Supernova Remnants

The spectra of protons and nuclei accelerated by supernova remnant (SNR) shocks are calculated, taking into account magnetic field amplification and Alfv´enic drift both upstream and downstream of the shock for different types of SNRs during their evolution. The maximum energy of accelerated particles may reach 5×1018 eV. The calculated energy spectrum of cosmic rays after propagation through the Galaxy is in good agreement with the spectrum measured at the Earth. The data obtained in ATIC-2, CREAM and PAMELA experiments revealed new features in cosmic ray spectra. It was found that elemental interstellar spectra of cosmic rays are not simple power laws and become more flat at magnetic rigidity above about 200 GV. A concavity of cosmic ray spectrum due to the nonlinear nature of shock acceleration is a possible reason for this hardening. Another feature – the increase with energy of the helium-to-proton ratio in cosmic rays can be explained in the model where particles are accelerated by forward and reverse shocks.

Sponsored by: Department of Physics and the Institute for Physical Science and Technology, University of Maryland. For information call Catha Stewart at (301) 405-4811 or go to the UMD Space Physics group seminar web site.

There is free parking after 4:00 PM in lot B (the big parking garage across the street from the ATL building). There are a limited number of spaces in lot Q next to the new ATL wing with free parking after 4PM even when there is a basketball game on campus.