Mysterious flares in the sky brighter than a trillion suns are actually the glow from two distant circling black holes, astronomers have confirmed in new observations that solve a decades-long mystery. New research finds that the galaxy OJ 287, which lies 5 billion light-years from Earth in the constellation Cancer, is anchored by two black holes, one supermassive and one smaller. Although these two black holes look like a dot in telescope images, they send out different types of electromagnetic signals, allowing astronomers to tease out their respective identities.
The galaxy was discovered in 1888, and astronomers have suspected for decades that it might be a binary system, with two black holes at its core. The galaxy shows an emission pattern that varies in two separate cycles, one of 12 years and the other of 55 years, suggesting that two separate types of motion are occurring: one, the orbit of one black hole around another; the other, the slow change in the orientation of that orbit.
Years of observation have revealed flashes that occur when one black hole plunges through the accretion disk of the other (huge rings of matter swirling around supermassive black holes), heating up the disk’s dust and gas and creating dramatic flashes of energy throughout. the electromagnetic spectrum. These flares are brighter than a trillion stars and last about two weeks. Now, however, researchers have observed two even more dramatic and much shorter-lived flashes from the binary system, directly confirming the existence of the two black holes.
During the 2021-2022 observations, researchers led by astronomer Staszek Zola of the Jagiellonian University in Krakow, Poland, saw a flare that produced 100 times more light than an entire galaxy. This flash lasted only one day. NASA’s Fermi telescope also detected a second, equally brief gamma ray flare. The short duration of these eruptions made them easy to go unnoticed for decades. “OJ 287 has been recorded in photographs since 1888 and has been intensively followed since 1970,” the study’s lead author. Mauri Valtonen of the Tata Institute for Fundamental Research in Mumbai, India, said in a statement. “It turns out that we have simply been unlucky. No one observed OJ 287 on exactly those nights when it did its one-night stand.”
So what is going on? The researchers estimate that the smallest black hole in OJ 287 is about 150 million times the mass of our sun. The first giant flare occurred because this small black hole was infused with new gas to swallow, which led to a jet of material forming and shooting out of the small black hole.
Soon after, the small black hole passed through the accretion disk of the huge black hole, which is 18 billion times the mass of our sun. The jet interacted with the disk, creating the gamma-ray flare detected by the Fermi telescope.
The researchers report their findings in the June issue of The Monthly Notices of the Royal Astronomical Society.