Speakers
Description
Young supernova remnants (SNRs), only a few hundred years old, are among the most energetic and dynamic environments in the Galaxy. Their fast shocks (travelling at thousands of km/s) and amplified magnetic fields (0.1–1 G) create ideal conditions for cosmic-ray acceleration. At the same time, high-energy electrons undergo rapid synchrotron cooling, which counteracts acceleration. This balance between gain and loss emerges observationally as year-scale variability in hard X-ray synchrotron emission. Tracking the evolution of hard X-ray flux and spectral shape, therefore, provides direct insight into ongoing particle acceleration.
In this talk, I present multi-epoch NuSTAR observations of four historic young SNRs—Cassiopeia A, G1.9+0.3, Kepler, and Tycho. I report spectral changes in the hard X-ray band and the interpretation of these results in the context of ongoing electron acceleration. Finally, I discuss the implications for proton acceleration in young SNRs and the possibility of corresponding variability in their gamma-ray emission.
