The centers of galaxies with actively feeding supermassive black holes are already astounding environments. Now, a team of researchers led by a graduate student from the University of Hawaiʻi Institute for Astronomy (IfA) has found an even more interesting oddball. Feeding black holes typically increase and decrease in brightness similar to the Kilauea volcano, becoming more or less active over time in unpredictable ways. However, the newly discovered black hole is more like Old Faithful geyser at Yellowstone National Park, erupting repeatedly at predictable times.
Astronomers classify galaxies with unusually bright and variable centers as active galaxies. The active centers can produce much more energy than the combined contribution of all the stars in the host galaxy. The excess energy can be seen at visible, ultraviolet, and X-ray wavelengths. Astrophysicists think the extra emission comes from near the galaxy’s central supermassive black hole, where a swirling disk of gas and dust accumulates and heats up because of gravitational and frictional forces. The black hole slowly consumes the material, which usually creates low-level, random changes in the disk’s emitted light.