Broad - band Observations and Modeling of the Shell - Type Supernova Remnant G 347 . 3 - 0 . 5

The supernova remnant G347.3–0.5 emits a featureless power-law in X-rays, thought to indicate shock-acceleration of electrons to high energies. We here produce a broadband spectrum of the bright NW limb of this source by combining radio observations from the Australia Telescope Compact Array (ATCA), X-ray observations from the Advanced Satellite for Cosmology and Astrophysics (ASCA), and TeV γ-ray observations from the CANGAROO imaging Čerenkov telescope. We assume this emission is produced by an electron population generated by diffusive shock acceleration at the remnant forward shock. The nonlinear aspects of the particle acceleration force a connection between the widely different wavelength bands and between the electrons and the unseen ions, presumably accelerated simultaneously with the electrons. This allows us to infer the relativistic proton spectrum and estimate ambient parameters such as the supernova explosion energy, magnetic field, matter density in the emission region, and efficiency of the shock acceleration process. We find convincing evidence that the shock acceleration is efficient, placing > 25% of the shock kinetic energy flux into relativistic ions. Despite this high efficiency, the maximum electron and proton energies, while depending somewhat on assumptions for the compression of the magnetic field in the shock, are well below the observed ‘knee’ at ∼ 1015 eV in the Galactic cosmic-ray spectrum. Subject headings: Supernova remnants — acceleration of particles — cosmic-rays — X-rays — radio — gamma-rays: ISM: individual (G347.3-0.5) Department of Physics, North Carolina State University, Box 8202, Raleigh NC 27695, U.S.A.; E-mail: don [email protected] Harvard Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, U.S.A.; E-mail: [email protected] Hubble Fellow Center for Space Research, Massachusetts Institute for Technology, Cambridge, MA 02139, U.S.A.; E-mail: [email protected]