Imprints of cosmic ray acceleration in supernova remnants: Cassiopeia A and RCW 86.

Eveline Helder (Univ. Utrecht) - Aug 31, 2009 at 12:10 pm

Supernova remnants are the prime candidates for accelerating cosmic rays up to 10^15 eV and possibly up to 10^18 eV. For decades, the main reason for believing this was the energy budget; there are no other sources known in the Galaxy which can provide this amount of energy.
Over the past two decades, this claim has been enforced by observational evidence. First, there was the detection of X-ray synchrotron emission at the shock fronts of several supernova remnants, revealing 10^13 eV electrons. Later, there was the detection of TeV gamma-rays from several remnants.
Since a significant fraction of the energy of the supernova remnant is transferred to accelerating cosmic rays, we can look for imprints of this acceleration process in the kinematics of the remnants themselves. Examples of these imprints are magnetic field amplification and a lower post shock temperature due to the acceleration process.
I will describe recent work we have done on the non-thermal X-ray emission of Cassiopeia A. Using Chandra data, we found that this non- thermal emission does not originate from the outer shock solely. Additionally, an emission process different from X-ray synchrotron emission is unlikely, implying that the reverse shock is capable of accelerating electrons as well.
I will describe our latest findings on the RCW 86 remnant as well. Using optical spectra combined with an X-ray proper motion study, we found that cosmic rays efficiently act as a heat sink in this remnant. We measure that over 50% of the shock energy goes into accelerating cosmic rays.

The seminar will be held in 544 Campbell Hall.


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