Orateur
Dr
Giovanni Morlino
(Arcetri observatory)
Description
We calculate the flux of non-thermal radiation from the Tycho's supernova remnant in the context of the non-linear theory of particle acceleration at shocks, which allows us to take into account self-consistently the dynamical reaction of the accelerated particles, the generation of magnetic fields in the shock proximity and the dynamical reaction of the magnetic field on the plasma.
Assuming a modest acceleration efficiency we find that the strength of the magnetic field obtained as a result of streaming instability induced by cosmic rays is compatible with the interpretation of the X-ray emitting filaments being produced by strong synchrotron losses in ~300 μG magnetic fields.
In such a strong magnetic field the magnetic turbulence in the upstream region of the shock can move with a speed which is a non negligible fraction of the shock speed. As a consequence the accelerated particles feel an effective compression factor less than 4 and their energy spectrum is steeper than the standard prediction, $n(E)\propto E^{-2}$.
Taking into account the speed of magnetic turbulence, we consistently predict the observed gamma-ray spectrum, from the GeV band observed by FermiLAT up to the TeV band observed by VERITAS, as due to pion decay produced in hadronic collisions of a population of accelerated ions with a slope ~2.2.
Remarkably the same model predict a relativistic electron population whose synchrotron emission well explain both the radio spectral index of 0.65, as well as the non-thermal X-ray emission.
