22-24 May 2013
Physics Department, University "La Sapienza", Roma, Italy
Europe/Rome timezone

Efficient turbulent amplification of magnetic field driven by dynamo effect at supernova remnant shocks

22 May 2013, 15:30
15m
Aula Giorgio Careri (first floor) (Physics Department, University "La Sapienza", Roma, Italy)

Aula Giorgio Careri (first floor)

Physics Department, University "La Sapienza", Roma, Italy

Speaker

Dr Federico Fraschetti (University of Arizona)

Description

Supernova Remnant (SNR) shocks are considered the main source of galactic cosmic-rays at least up to the knee of the cosmic-ray spectrum, and possibly further. From recent high-energy observations of SNRs a magnetic field at the shock far exceeding the theoretically predicted shock-compressed field has been inferred. Theoretical work in the last decade has linked particles accelerated at the shock to such an amplification. We show that density inhomogeneities in the interstellar medium might strongly enhance the magnetic field, regardless any cosmic-rays influence. The growth of the turbulent component of the downstream magnetic field is driven by the vortical eddies motion. We determine the time-evolution and saturation of the amplified field. The explicit expression of growth rate and non-linear field back-reaction in terms of the parameters of shock and interstellar density fluctuations is derived from jump conditions. Field saturation up to the order of milligauss and a short-time variability in the X-ray observations of SNRs can be obtained by using reasonable parameters for the interstellar turbulence.

Primary author

Dr Federico Fraschetti (University of Arizona)

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