TY  - JOUR
AU  - Pohl, Martin
AU  - Wilhelm, A.
AU  - Telezhinsky, I.
TI  - Reacceleration of electrons in supernova remnants
JO  - Astronomy and astrophysics
VL  - 574
IS  - arXiv:1411.2891
SN  - 1432-0746
CY  - Les Ulis
PB  - EDP Sciences
M1  - PUBDB-2016-00423
M1  - arXiv:1411.2891
SP  - A43 -
PY  - 2015
N1  - (c) ESO. The arXiv version v1 does match with the post referee version.
AB  - In this paper we determine the effect of stochastic reacceleration on the spectra of electrons in the GeV band and at lower energies, and we investigate whether reacceleration can explain the observed variation in radio spectral indices.Methods. We explicitely calculated the momentum diffusion coefficient for 3 types of turbulence expected downstream of the forward shock: fast-mode waves, small-scale non-resonant modes, and large-scale modes arising from turbulent dynamo activity. After noting that low-energy particles are efficiently coupled to the quasi-thermal plasma, a simplified cosmic-ray transport equation can be formulated and is numerically solved.Results. Only fast-mode waves can provide momentum diffusion fast enough to significantly modify the spectra of particles. Using a synchrotron emissivity that accurately reflects a highly turbulent magnetic field, we calculated the radio spectral index and find that soft spectra with index α ≲ − 0.6 can be maintained over more than 2 decades in radio frequency, even if the electrons experience reacceleration for only one acceleration time. A spectral hardening is possible but considerably more frequency-dependent. The spectral modification imposed by stochastic reacceleration downstream of the forward shock depends only weakly on the initial spectrum provided by, e.g., diffusive shock acceleration at the shock itself.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000349467000043
DO  - DOI:10.1051/0004-6361/201425027
UR  - https://bib-pubdb1.desy.de/record/293268
ER  -