Some of the brightest objects in the Universe — quasars — are vanishing rapidly. Astronomers now think that they understand this mysterious behaviour1, 2, and the answer could help them to explain how galaxies such as the Milky Way evolve.
Quasars are supermassive black holes at the centres of galaxies fed by huge quantities of gas that shine across the visible Universe. Astronomers have long thought that quasars persist for millions of years before dimming slowly over tens of thousands of years. But in 2014, Stephanie LaMassa, an astronomer now at the Space Telescope Science Institute in Baltimore, Maryland, discovered a quasar that seemed to disappear in less than ten years3. That’s a blink of an eye, astronomically speaking.
Researchers struggled to explain the oddity. Perhaps a massive dust cloud passed in front of the quasar’s bright beacon and momentarily blocked its light. Or maybe a star passed too close to the black hole and was rapidly torn apart, causing a bright flare that scientists mistook for a quasar. It seemed physically impossible that such a bright object could fade in such a short time.
To read more, click here.