2019ApJ...876...24Z -
Astrophys. J., 876, 24-24 (2019/May-1)
Electron acceleration in middle-age shell-type γ-ray supernova remnants.
ZHANG X. and LIU S.
Abstract (from CDS):
Over the past decade, γ-ray observations of supernova remnants (SNRs) and accurate cosmic-ray (CR) spectral measurements have significantly advanced our understanding of particle acceleration in SNRs. In combination with multiwavelength observations of a large sample of SNRs, it has been proposed that the highest energy particles are mostly accelerated in young remnants, and the maximum energy that middle-age and old SNRs can accelerate particles to decreases rapidly with the decrease in shock speed. If SNRs dominate the CR flux observed at Earth, a large number of particles need to be accelerated in old SNRs for the soft CR spectrum even though they cannot produce very high-energy CRs. With radio, X-ray, and γ-ray observations of seven middle-age shell-type SNRs, we derive the distribution of high-energy electrons trapped in these remnants via a simple one-zone leptonic emission model and find that their spectral evolution is consistent with such a scenario. In particular, we find that particle acceleration by shocks in middle-age SNRs with age t can be described by a unified model with the maximum energy decreasing as t–3.1 and the number of GeV electrons increasing as t2.5 in the absence of escape from SNRs.
Abstract Copyright:
© 2019. The American Astronomical Society. All rights reserved.
Journal keyword(s):
gamma rays: ISM - ISM: supernova remnants - radiation mechanisms: non-thermal
Simbad objects:
16
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