Lighting up the sky: What gamma rays reveal about supernova remnant shocks (and shocks in general)

Gamma-ray observations over the past decade—from space-based instruments like Fermi-LAT to ground-based arrays such as H.E.S.S., MAGIC, and VERITAS—have provided an increasingly detailed view of supernova remnants (SNRs). Several dozens of SNRs have been detected in the GeV–TeV energy range, revealing a diverse population shaped by their environments and evolutionary stages, and new detections continue to expand the catalog of gamma-ray bright remnants. Observations by HAWC and LHAASO have even identified a few Galactic PeVatron candidates, though a direct connection to SNRs remains under investigation. Beyond remnants, gamma-ray detections from novae also underscore the ubiquity of shock-powered emission across explosive astrophysical systems. This review will highlight recent gamma-ray results offering fresh insight into the radiative signatures and energetic processes associated with supernova remnant shocks.