Starving black hole returns brilliant galaxy to the shadows

Many galaxies are found to have an extremely bright core powered by a supermassive black hole. These cores make “active galaxies” some of the brightest objects in the Universe. They are thought to shine so brightly because hot material is glowing fiercely as it falls into the black hole, a process known as accretion. This brilliant light can vary hugely between different active galaxies, so astronomers classify them into several types based on the properties of the light they emit.