2008/08/31 by Julien Lavalle, J. Lavalle, E. Nezri +6 · 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.78.103526
published as Phys.Rev.D78:103526,2008 · 19 pages, 9 figures. Backgrounds included and additional comments and figures on the positron fraction. Accepted for publication in PRD
arxiv created 2008/10/24 · openalex publication_date 2008/11/25 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
While the particle hypothesis for dark matter may be very soon investigated at the LHC, and as the PAMELA and GLAST satellites are currently taking new data on charged and gamma cosmic rays, the need of controlling the theoretical uncertainties affecting the possible indirect signatures of dark matter annihilation is of paramount importance. The uncertainties which originate from the dark matter distribution are difficult to estimate because current astrophysical observations provide rather weak dynamical constraints and because, according to cosmological N-body simulations, dark matter is neither smoothly nor spherically distributed in galactic halos. Some previous studies made use of N-body simulations to compute the \ensuremathγ-ray flux from dark matter annihilation, but such a work has never been performed for the antimatter (positron and antiproton) primary fluxes, for which transport processes complicate the calculations. We take advantage of the galaxylike 3D dark matter map extracted from the Horizon Project results to calculate the positron and antiproton fluxes from dark matter annihilation, in a model-independent approach as well as for dark matter particle benchmarks relevant at the LHC scale (from supersymmetric and extradimensional theories). We find that the flux uncertainties arise mainly from fluctuations of the local dark matter density, and are of \ensuremath∼1 order of magnitude. We compare our results to analytic descriptions of the dark matter halo, showing how the latter can well reproduce the former. The overall antimatter predictions associated with our benchmark models are shown to lie far below the existing measurements and, in particular, that of the positron fraction recently reported by PAMELA, and far below the background predictions as well. Finally, we stress the limits of the use of an N-body framework in this context.