  Recently measured VHE gamma ray spectra from supernovae remnants (SNRs) are
best fit by power laws with an exponential cutoff. But this feature does not
occur at the `knee-equivalent' energy at which VHE gamma ray spectra are
expected to reflect the `knee' in the otherwise featureless cosmic ray
spectrum. In this article, the VHE gamma ray feature is explained as a
consequence of a recently deduced quantum effect. The effect distinguishes
`trajectory energy' from `particle state energy' and requires that the particle
state energy depends strongly on gravitational potential at very high energies.
Based on this effect and the observed CR spectrum, a tight two-parameter fit is
obtained to the combined VHE gamma ray spectra of SNRs RX J1713.7-3946 and RX
J0852.0-4622 and the Galactic Center ridge.

Astrophysics