COSMIC-RAY ELECTRON EVOLUTION IN THE SUPERNOVA REMNANT RX J1713.7-3946

A simple formalism to describe nonthermal electron acceleration, evolution, and radiation in supernova remnants (SNRs) is presented. The electron continuity equation is analytically solved assuming that the nonthermal electron injection power is proportional to the rate at which the kinetic energy of matter is swept up in an adiabatically expanding SNR shell. We apply this model to Fermi and HESS data from the SNR RX J1713.7-3946 and find that a one-zone leptonic model with Compton-scattered cosmic microwave background and interstellar infrared photons has difficulty providing a good fit to its spectral energy distribution, provided the source is at a distance similar to 1 kpc from the Earth. However, the inclusion of multiple zones, as hinted at by recent Chandra observations, does provide a good fit, but requires a second zone of compact knots with magnetic fields B similar to 16 mu G, comparable to shock-compressed fields found in the bulk of the remnant.