AAS 205th Meeting, 9-13 January 2005
Session 84 ISM III, SNe and Stirring the Soup
Oral, Tuesday, January 11, 2005, 2:00-3:30pm, Pacific 2/3

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[84.02] Evidence of Bohm Diffusion in Historical Supernova Remnants

G.E. Allen, M.D. Stage, J.C. Houck (MIT CSR)

Some shell-type supernova remnants are reported to emit X-ray synchrotron radiation. The values of the ``cut-off'' frequencies obtained by fitting the X-ray spectra with models of synchrotron emission have been used to estimate the ``maximum'' electron energies and magnetic field strengths of the remnants. We show that the cut-off frequencies and shock velocities can be used to set upper limits on the electron diffusion coefficient of the remnants. The limits for some historical remnants are very close to the Bohm limit. Therefore these remnants are accelerating electrons about as fast as possible. While the remnants cannot accelerate electrons beyond about 100~TeV, they may be capable of accelerating protons to energies of about 1000~TeV (i.e.\ to energies near the ``knee'' in the cosmic-ray spectrum). These results support the hypothesis that Galactic cosmic rays are predominantly accelerated in the shocks of supernova remnants.

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© 2004. The American Astronomical Society.