# Intro - What is "High-Energy"? --> defining "high-energy" - anything bursty or transient - a loose term for the behavior of matter at exterme densities and temperatures, high velocities, enormous magnetic fields and strong gravity - for frame of reference: the sun burning hydrogen to helium 10^38 times a second in the core is not typically considered high-energy! - However, a star exploding and releasing the same energy in a few seocnds that it would over the entre lifetime of fusion would be considered high-energy # High-Energy Events and Where to Find Them ## AGN (seyfert galaxies, quasars): - high energy event, black hole glowing ## supernovae ## tidal disruption events ## neutron stars ## kilonovae ## gamma ray bursts