3 research outputs found
PAMELA and dark matter
Assuming that the positron excess in PAMELA satellite data is a consequence
of annihilations of cold dark matter, we consider from a model-independent
perspective if the data show a preference for the spin of dark matter. We then
perform a general analysis of annihilations into two-body final states to
determine what weighted combination of channels best describes the data.Comment: 6 pages, 9 figures, 3 tables. Expanded and updated with published
PAMELA dat
Cosmic-ray knee and diffuse gamma, e+ and pbar fluxes from collisions of cosmic rays with dark matter
In models with extra dimensions the fundamental scale of gravity M_D could be
of order TeV. In that case the interaction cross section between a cosmic
proton of energy E and a dark matter particle \chi will grow fast with E for
center of mass energies \sqrt{2m_\chi E} above M_D, and it could reach 1 mbarn
at E\approx 10^9 GeV. We show that these gravity-mediated processes would break
the proton and produce a diffuse flux of particles/antiparticles, while
boosting \chi with a fraction of the initial proton energy. We find that the
expected cross sections and dark matter densities are not enough to produce an
observable asymmetry in the flux of the most energetic (extragalactic) cosmic
rays. However, we propose that unsuppressed TeV interactions may be the origin
of the knee observed in the spectrum of galactic cosmic rays. The knee would
appear at the energy threshold for the interaction of dark matter particles
with cosmic protons trapped in the galaxy by \muG magnetic fields, and it would
imply a well defined flux of secondary antiparticles and TeV gamma rays.Comment: 19 pages, references added, version to appear in JCA