Discovery of Secondary Supermassive Black Hole in Binary System

Astronomers have detected a secondary supermassive black hole in the well-known binary system of OJ287, located 5 billion light years away in the constellation Cancer. The black holes are so close together that they merge into one dot, but the team was able to observe signals from both black holes through flares and gamma rays. The smaller black hole was directly observed for the first time, producing a blue flash and a one-day burst of light. These efforts make OJ287 the best candidate for a supermassive black hole pair that is sending gravitational waves in nano-hertz frequencies.