A new view of the gamma-ray gap: 14 years of Fermi data reveal around 450 sources in a largely unexplored energy range

The universe is filled with light at many different energies. Some of it is invisible to our eyes, including extremely energetic gamma rays, which can only be produced in the most extreme environments in our universe, for example supermassive black holes, exploding stars or astrophysical jets. To "see" gamma rays, astrophysicists use particle experiments in space, such as the Fermi-Large Area Telescope (Fermi-LAT). This instrument was launched into space by NASA in 2008, and it can detect photons from 20 megaelectronvolts (MeV, a unit of energy) to beyond 1 teraelectronvolt (TeV).