  A number of supernova remnants (SNRs) show nonthermal X-rays assumed to be
synchrotron emission from shock accelerated TeV electrons. The existence of
these TeV electrons strongly suggests that the shocks in SNRs are sources of
galactic cosmic rays (CRs). In addition, there is convincing evidence from
broad-band studies of individual SNRs and elsewhere that the particle
acceleration process in SNRs can be efficient and nonlinear. If SNR shocks are
efficient particle accelerators, the production of CRs impacts the thermal
properties of the shock heated, X-ray emitting gas and the SNR evolution. We
report on a technique that couples nonlinear diffusive shock acceleration,
including the backreaction of the accelerated particles on the structure of the
forward and reverse shocks, with a hydrodynamic simulation of SNR evolution.
Compared to models which ignore CRs, the most important hydrodynamical effects
of placing a significant fraction of shock energy into CRs are larger shock
compression ratios and lower temperatures in the shocked gas. We compare our
results, which use an approximate description of the acceleration process, with
a more complete model where the full CR transport equations are solved (i.e.,
Berezhko et al., 2002), and find excellent agreement for the CR spectrum summed
over the SNR lifetime and the evolving shock compression ratio. The importance
of the coupling between particle acceleration and SNR dynamics for the
interpretation of broad-band continuum and thermal X-ray observations is
discussed.
