A Spatially Resolved Study of Hard X-Ray Emission in Kepler’s Supernova Remnant: Indications of Different Regimes of Particle Acceleration

Abstract Synchrotron X-ray emission in young supernova remnants (SNRs) is a powerful diagnostic tool to study the population of high-energy electrons accelerated at the shock front and the acceleration process. We performed a spatially resolved spectral analysis of NuSTAR and XMM-Newton observations of the young Kepler’s SNR, aiming to study in detail its nonthermal emission in hard X-rays. We selected a set of regions all around the rim of the shell and extracted the corresponding spectra. The spectra were analyzed by adopting a model of synchrotron radiation in the loss-limited regime, to constrain the dependence of the cutoff energy of the synchrotron radiation on the shock velocity. We …