Galactic cosmic rays
Seminars
Seminar “Theory of Fundamental Interactions”
Date and Time: Thursday, 30 May 2019, at 4:00 PM
Venue: Lecture Hall (2nd floor), Bogoliubov Laboratory of Theoretical Physics
Seminar topic: “Galactic cosmic rays”
Speaker: Dmitri Semikoz (Laboratory of Astroparticle Physics and Cosmology, Paris)
Abstract:
In this talk, I review the experimental and theoretical status of Galactic cosmic rays. I will show that the standard static isotropic model of galactic cosmic ray propagation suggested in 1990th is in direct contradiction with large number of modern observations, which include variability of cosmic ray flux in the Galaxy, magnetic field measurements and large number of anomalies in local cosmic ray observations. I will present a new model of galactic cosmic rays, which takes into account anisotropic propagation of cosmic rays. Within this model, only a few nearby supernovae give a dominant contribution to the local cosmic ray flux at energies above 200 GeV.
One can explain multiple anomalies in the cosmic ray data by adding the effects of a 2 billion-year-old nearby supernova. In particular, this supernova can explain the excess of positrons and antiprotons above 20 GeV found by PAMELA and AMS-02, the discrepancy in the slopes of the spectra of cosmic ray protons and heavier nuclei in the TeV-PeV energy range and the plateau in cosmic ray dipole anisotropy in the 2-50 TeV energy range. The same supernova was responsible for 60Fe measured in the ocean crust. The cosmic rays above 200 TeV in the knee region together with the excess in astrophysical neutrino data can be explained by another nearby supernova, Vela, located at 270 pc from the Sun.