Supermassive black holes at the centers of galaxies are one of the most active fields of research in astronomy. In order to accumulate their enormous masses, they must merge with each other. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy (MPIfR) in Bonn has found direct evidence of two supermassive black holes in the galaxy Markarian 501, which orbit each other very closely. This could be the first time that a pair has been detected that is about to merge. This provides a unique opportunity to better understand a central process in galaxy evolution.