What can the most energetic light in the universe reveal about its most extreme environments?
Gamma rays, the highest-energy form of electromagnetic radiation, are produced by the most violent processes in the cosmos. Emerging from relativistic jets, supernova remnants, pulsars, and other powerful astrophysical accelerators, they carry distinct signatures of particle acceleration and high-energy interactions. Observing these gamma rays allows us to probe environments where particles are accelerated to extreme energies, uncovering physical processes that remain invisible in lower-energy spectra. Gamma-ray astronomy thus provides a unique window into the non-thermal universe, playing a pivotal role in the emerging era of multi-messenger astrophysics alongside neutrino and gravitational-wave observations.