A joint spectral analysis of some Chandra ACIS X-ray data and Molonglo Observatory Synthesis Telescope radio data was performed for 13 small regions along the bright northeastern rim of the supernova remnant SN 1006 .
These data were fitted with a synchrotron radiation model .
The nonthermal electron spectrum used to compute the photon emission spectra is the traditional exponentially cut off power law , with one notable difference : The power-law index is not a constant .
It is a linear function of the logarithm of the momentum .
This functional form enables us to show , for the first time , that the synchrotron spectrum of SN 1006 seems to flatten with increasing energy .
The effective power-law index of the electron spectrum is 2.2 at 1 GeV ( i.e. , radio synchrotron–emitting momenta ) and 2.0 at about 10 TeV ( i.e. , X-ray synchrotron–emitting momenta ) .
This amount of change in the index is qualitatively consistent with theoretical models of the amount of curvature in the proton spectrum of the remnant .
The evidence of spectral curvature implies that cosmic rays are dynamically important instead of being “ test ” particles .
The spectral analysis also provides a means of determining the critical frequency of the synchrotron spectrum associated with the highest-energy electrons .
The critical frequency seems to vary along the northeastern rim , with a maximum value of 1.1 ^ { +1.0 } _ { -0.5 } \times 10 ^ { 17 } Hz .
This value implies that the electron diffusion coefficient can be no larger than a factor of \sim 4.5–21 times the Bohm diffusion coefficient if the velocity of the forward shock is in the range 2300–5000 km s ^ { -1 } .
Since the coefficient is close to the Bohm limit , electrons are accelerated nearly as fast as possible in the regions where the critical frequency is about 10 ^ { 17 } Hz .