Astrophysicists detect most luminous diffuse gamma-ray emission from Arp 220

Astronomers have detected for the first time the most luminous gamma-ray emission from the merging galaxy Arp 220 — the nearest ultraluminous infrared galaxy to Earth reveals the hidden extreme energetic processes in galaxies. Luminous infrared galaxies and ultraluminous infrared galaxies are the most luminous of all galaxies.