OJ 287 has the most supermassive pair of black holes ever

"The closest supermassive black hole pair, in NGC 7727, was discovered in 2021. Just 89 million light-years away, these 154,000,000- and 6,300,000-solar-mass black holes are just 1,600 light-years apart. Approximately 0.1% of young quasars are expected to be doubles, with typical separations of ~10,000 light-years."

"OJ 287: still the most extreme supermassive binary, 3.5 billion light-years away. First spotted in 1887, it flares with a double burst every 12 years. Its main black hole is enormous: 18.35 billion solar masses. Its event horizon is 12 times the size of Neptune's orbit."

"The periodic double burst arises when the smaller black hole punches through the larger's accretion disk. With a 12-year orbit, it varies from 0.05 to 0.28 light-years away from the primary. The secondary black hole precesses 39° with every orbit: a fantastic confirmation of General Relativity's predictions."

Supermassive black hole pairs have been discovered at various distances from Earth. NGC 7727 contains the closest known pair, separated by 1,600 light-years with masses of 154 million and 6.3 million solar masses. Double quasars, containing two supermassive black holes each, occur in approximately 0.1% of young quasars with typical separations around 10,000 light-years. OJ 287 represents the most extreme binary system, located 3.5 billion light-years away. Its primary black hole contains 18.35 billion solar masses with an event horizon 12 times Neptune's orbital size. The companion black hole has 150 million solar masses. The system produces distinctive double bursts every 12 years when the smaller black hole passes through the larger one's accretion disk. The secondary black hole's orbit demonstrates 39-degree precession, confirming General Relativity predictions. These two black holes are expected to merge within approximately 10,000 years.

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