You might think that astronomers could easily tell the difference between a black hole and a white dwarf — but nature can be deceptive. Astronomers from the Sloan Digital Sky Survey (SDSS) have just announced the results of a new study that reveals the true origin of puzzling light from nearby galaxies.
Astronomers can’t find any sign of the black hole at the centre of the quasar SDSS J1011+5442, and they couldn’t be happier. The black hole is still there, of course, but over the past ten years, it appears to have swallowed all the gas in its vicinity. With the gas consumed, researchers were unable to detect the spectroscopic signature of the quasar, which now appears as an otherwise normal galaxy.
Astronomers using NASA’s Hubble Space Telescope have found that Markarian 231, the nearest galaxy to Earth that hosts a quasar, is powered by two central black holes. The finding suggests that quasars — the brilliant cores of active galaxies — may commonly host two central supermassive black holes that fall into orbit about one another as a result of galactic mergers.
Hitting the jackpot is one thing, but if you hit the jackpot four times in a row you might wonder if the odds were somehow stacked in your favour. A group of astronomers led by Joseph Hennawi of the Max Planck Institute for Astronomy have found themselves in exactly this situation. They discovered the first known quasar quartet: four quasars, each one a rare object in its own right, in close physical proximity to each other.