2018/12/31 by David Dunsky, Lawrence J. Hall, Keisuke Harigaya · 1 citation
Physics and Astronomy · #astro-ph.HE #astro-ph.CO #hep-ex #hep-ph
paper · pdf · doi:10.1088/1475-7516/2019/07/015
published as JCAP 07 (2019) 015 · 56 pages, 20 figures. Matches published version. Added discussion on EDGES result, clarifications, and references
arxiv created 2019/07/10 · arxiv updated 2019/07/12
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 \mathop\textstyle ∼\textstyle < 1010 q ~\rm GeV, there is a large flux of accelerated X in the disk today, with a momentum distribution ∝ 1/p2.5 extending to (βp)max ∼ 5 ×104 q ~\rm 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. For m \mathop\textstyle ∼\textstyle > 1010 q ~\rm GeV, X cannot be accelerated above the escape velocity within the lifetime of the shock. 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.