David Dunsky (UC Berkeley) “CHAMP Cosmic Rays”

Seminar Organizer

Abstract: We study interactions of cosmological relics, X, of mass m and electric charge qe in the galaxy, including thermalization with the interstellar medium, diffusion through inhomogeneous magnetic fields and Fermi acceleration by supernova shock waves. We find that for m < 10^10 q GeV, there is a large flux of accelerated X in the disk today, with a momentum distribution 1/p^2.5 extending to (βp)max ~ 5×10^4 q GeV. Even though acceleration in supernova shocks is efficient, ejecting X from the galaxy, X are continually replenished by diffusion into the disk from the halo or confinement region. The accelerated X form a component of cosmic rays that can easily reach underground detectors, as well as deposit energies above thresholds, enhancing signals in various experiments. We find that nuclear/electron recoil experiments place very stringent bounds on X at low q; for example, X as dark matter is excluded for q above 10−9 for any m. For larger q, stringent bounds on the fraction of dark matter that can be X are set by Cherenkov and ionization detectors. Nevertheless, very small q is highly motivated by the kinetic mixing portal, and we identify regions of (m,q) that can be probed by future experiments.