Electron-Ion Temperature Equilibration at Collisionless Shocks in Supernova Remnants
Cara Rakowski (CfA) - Apr 11 at 12:00 noon
The acceleration of particles to both thermal and cosmic-ray
energies in collisionless shocks requires the interplay of
multiple magneto-hydrodynamic instabilities at the shock.
Although the high-mach number shocks in supernova remnants
(SNRs) are widely regarded as the source for the bulk of the
cosmic-ray spectrum, the efficiency of these processes in
real shocks has yet to be ascertained. In this talk I will
review the current state of our knowledge about the degree of
initial temperature equilibration between electrons, protons
and ions at SNR shocks. Specifically, the question has been
raised as to whether there is an inverse relationship between
the shock velocity and the equilibration of the thermal
populations similar to the relationship between Alfven Mach
number and equilibration seen in interplanetary shocks. I
review the methods that have been used to measure the
equilibration, their problems and uncertainties and how those
would effect the degree of equilibration (or velocity)
inferred. Current Chandra X-ray observations of SNRs have
great potential to shed more light on this question, and some
first results will be presented.
The seminar will be held in 544 Campbell Hall.
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