  Explicitly time-dependent, nonlinear kinetic theory of cosmic ray (CR)
acceleration in supernova remnants (SNRs) has been used to investigate the
properties of the very large SNR RX J0852.0-4622. The available observations do
not clearly distinguish between a ``nearby'' (at $\sim 200$ pc) and a
``distant'' (at $\sim 1$ kpc) source scenario. Therefore two correspondingly
different models were analyzed. While the 200 pc solution can not be a priory
excluded, the 1 kpc solution turns out to be clearly preferable for physical
reasons. It requires a core collapse supernova (SN) with a massive progenitor
in a molecular cloud $\sim 4000$ yrs ago. The overall synchrotron spectrum and
the filamentary structures in hard X-rays both consistently lead to an
amplified magnetic field $B > 100 \mu$G in the SNR interior. This implies a
suppression of the leptonic TeV $\gamma$-ray emission to about 1 percent of the
flux measured by the H.E.S.S. telescope system which therefore must be
hadronic, consistent with the theoretical solution. Up to the present the 1 kpc
solution has already converted $\sim 10$ percent of the explosion energy into
nonthermal energy, as expected for a Galactic CR source. Also the derived
$\gamma$-ray morphology is consistent with the H.E.S.S. measurements. For the
``nearby'' solution the leptonic and hadronic $\gamma$ ray fluxes are in the
ratio 1:10 which means that this case is also hadronically dominated. However,
the magnetic field strength, consistent with the overall synchrotron spectrum,
differs significantly from that derived from the X-ray filaments. Finally, the
total mechanical energy released amounts to only $1.8 \times 10^{50}$ erg,
uncomfortably low even for a core collapse event.
