Sep 12 – 16, 2016
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Non-linear diffusion of cosmic rays escaping from supernova remnants

Sep 15, 2016, 4:45 PM
6/2-024 - BE Auditorium Meyrin (CERN)

6/2-024 - BE Auditorium Meyrin


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Oral Contributions Cosmic rays Cosmic rays


Lara Nava


The mechanism through which cosmic rays (CRs) propagate away from their accelerators still remains an open issue. The main difficulty is the high non-linearity of the problem: CRs themselves excite the magnetic turbulence that confines them close to their sources. We solve numerically the coupled differential equations describing the evolution in space and time of the escaping particles and of the waves generated through the CR streaming instability. We consider two different phases of the interstellar medium, warm ionized and warm neutral, which are characterised by a significant presence of neutral particles. The friction between those neutrals and ions results in a very effective wave damping mechanism. It is found that streaming instability affects the propagation of CRs even in the presence of ion-neutral friction. The diffusion coefficient can be suppressed by more than a factor of $\sim 2$ over a region of few tens of pc around the remnant. The suppression increases for smaller distances. The propagation of $\approx 10$ GeV particles is affected for several tens of kiloyears after escape, while $\approx 1$ TeV particles are affected for few kiloyears. This might have a great impact on the interpretation of gamma-ray observations of molecular clouds located in the vicinity of supernova remnants.

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