http://www-cr.scphys.kyoto-u.ac.jp/research/xray/xray-e_large.html
The remnant of the brightest historical supernova exploded in AD1006, now provides
us with the first conclusive evidence for a lineless, power-low component of
X-ray emission from a shell supernova remnant, and thus represents the
nonthermal X-rays from shell SNRs. This implies that electrons emitting
synchrotron radiation at these X-ray energies must have energies of order 100
TeV, among the highest ever observed or directly inferred in any context,
astrophysical or otherwise. They are certainly the highest energies seen in
the absence of collapsed objects such as neutron stars of black holes.
Since
we are observing 8 keV synchrotron photons. The electrons producing them must
have energies of 2.e5 (B/10 microGauss)^-1/2 GeV, or 200 TeV for this magnetic
field. This energy is close to that of the 'knee' in the cosmic-ray spectrum,
and provides strong evidence that SNR shock waves can accelerate electrons to
these energies. The process of shock acceleration, while well-studied
theoretically, has lacked direct evidence of operation to the extremes of
energies for which it has been invoked, and SN1006 makes an important contribution
to providing such evidence.
Figure 1. The ASCA X-ray image of
SN1006. X-ray spectra were made from the two elliptical regions.
Figure
2. The X-ray spectra from the rim and central regions; the former is non-
thermal spectrum, while the latter is that of thin thermal plasma typical to shell-like
SNRs.