Supermassive Black Holes

Black holes are invisible. No light, neither visible light nor radowaves nor any other form of electromagnetic radiation, can escape the immense gravity of a black hole. So astronomers look for other clues when trying to discover Black holes out in the Universe.

Only the most massive stars end up as Black holes when they run out of fuel and explode in spectacular supernova explosions.  Sun-like stars do not end up as Black holes. But no single star is massive enough to create the Supermassive Black Holes that we discover at the center of galaxies. Those Supermassive Black Holes must be created in some other way.