High energy astronomy is the study of astronomical objects that release electromagnetic radiation of highly energetic wavelengths. It includes X-ray astronomy, gamma-ray astronomy, and extreme UV astronomy, as well as studies of neutrinos and cosmic rays. The physical study of these phenomena is referred to as high-energy astrophysics.Astronomical objects commonly studied in this field may include black holes, neutron stars, active galactic nuclei, supernovae, kilonovae, supernova remnants, and gamma ray bursts.