Everyone knows there is no sound in space. After all, a sound wave requires a medium, like air or water, to travel through, and space is mostly a vacuum. But in studying a nearby galaxy cluster, astronomers detected a true occurrence of sound in space—and in this case, the incredibly deep sound was coming from a black hole.
Scientists working with the Chandra X-ray Observatory were perplexed by the lack of star formation in the Perseus Cluster, a group of galaxies about 250 million light-years from Earth. The gas throughout the cluster was somehow remaining hot, rather than cooling and creating stars. Something was delivering energy to this gas, but what?
In 2002, Chandra scientists found an unexpected clue to this mystery—and it was coming from a super-massive black hole. Somehow, the black hole was emitting sound waves. In the fifth episode of “Sound Mysteries,” we explore the case of the black hole’s song, and how it might be key to understanding some of the largest structures in the universe.