2008/11/30 by Nicole F. Bell, Thomas D. Jacques, Thomas Jacques · 1 citation
Physics and Astronomy · #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #Particle physics theoretical and experimental studies #astro-ph #hep-ph
paper · pdf · doi:10.1103/physrevd.79.043507
published as Phys.Rev.D79:043507,2009 · 7 pages, 4 figures; version accepted for publication in Phys. Rev. D
openalex publication_date 2009/02/05 · arxiv created 2010/02/01 · arxiv updated 2010/02/08 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Dark matter annihilation into charged particles is necessarily accompanied by gamma rays, produced via radiative corrections. Internal bremsstrahlung from the final state particles can produce hard gamma rays up to the dark matter mass, with an approximately model-independent spectrum. Focusing on annihilation into electrons, we compute robust upper bounds on the dark matter self-annihilation cross section ⟨\ensuremathσAv⟩_e+e^\ensuremath- using gamma-ray data from the Milky Way spanning a wide range of energies \ensuremath∼10^\ensuremath-3--104 GeV. We also compute corresponding bounds for the other charged leptons. We make conservative assumptions about the astrophysical inputs, and demonstrate how our derived bounds would be strengthened if stronger assumptions about these inputs are adopted. The fraction of hard gamma rays near the end point accompanying annihilation to e+e^\ensuremath- is only a factor of \ensuremath\lesssim102 lower than for annihilation directly to monoenergetic gamma rays. The bound on ⟨\ensuremathσAv⟩_e+e^\ensuremath- is thus weaker than that for ⟨\ensuremathσAv⟩_\ensuremathγ\ensuremathγ by this same factor. The upper bounds on the annihilation cross sections to charged leptons are compared with an upper bound on the total annihilation cross section defined by neutrinos.