  The excess of continuum gamma-ray emission from the Galaxy above 1 GeV is an
unsolved puzzle. It may indicate that the interstellar nucleon or electron
spectra are harder than local direct measurements, as could be the case if a
local source of cosmic rays were to dominate the nearby flux. It is however
difficult to distinguish between the two cases. Cosmic-ray secondary
antiprotons provide a way to resolve this issue.
  We have made a calculation of the cosmic-ray secondary antiproton spectrum in
our model, which computes self-consistently propagation of primary and
secondary nucleons, and electrons. Fragmentation and energy losses are computed
using realistic distributions for the interstellar gas and radiation fields,
and diffusive reacceleration is also incorporated. Our study shows that
accurate measurements of the antiproton flux, especially at high energies,
could provide a diagnostic of the interstellar nucleon spectrum allowing us to
test the hard nucleon spectrum hypothesis. Present antiproton data above 3 GeV
indicate that it can already be excluded at the few sigma level.

Astrophysics;High Energy Physics - Phenomenology