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Gennady Detinich
Astronomers have long suspected that the quasar OJ 287 observed since 1888 in the constellation Cancer is a galaxy with two supermassive black holes at its center. But this galaxy is so far away from us, and the black holes are so close to each other that the signals from them merge into one point. The last cycle of observations for OJ 287 brought long awaited opening – Signals from a second black hole have been reliably detected for the first time.
Image Source: AAS 2018
The active galaxy OJ 287 is about 5 billion light-years away from us. This object has been observed by astronomers for 135 years and has been studied very well. This is an excellent target for testing astrophysical theories, which makes it possible to test certain models in practice. Observations over the past 40 years have made it possible to identify two cycles in the change in the activity of the galaxy. One of them is 12 years old and the other is 55 years old. The smaller cycle was obviously related to the orbital motion of the less massive black hole at the center of the galaxy around its much larger binary partner.
The largest supermassive black hole in this pair of black holes is considered the second largest among the discovered SMBHs. Its mass is about 18 billion solar masses. Simulations have shown that the smaller black hole in the pair has a mass of about 150 million solar masses. Against the background of a much larger partner, it was impossible to reliably detect it, and scientists only guessed about its presence.
A reliable sign of the discovery of a black hole can be the presence of an active accretion disk – a vast region of gas and dust, the part of which is closest to the hole is heated to billions of degrees Celsius. This area glows in almost all electromagnetic ranges, not to mention the periodic appearance of colossal energy emissions in the form of jets from the poles of the black hole, which are also perfectly recorded by our devices. It was by such signs that the largest black hole of this pair was detected.
Polish astronomers were able to detect the activity of a less massive black hole from a pair during observations in the 2021/2022 cycle. They noticed a short-lived bright flash, the duration of which lasted less than a day. An analysis of archival data showed that such phenomena could have been recorded earlier, but they were simply overslept. Modeling has shown that the short-lived flare is not a jet from the second SMBH (there is a different physics), but the moment when the less massive SMBH crosses the accretion disk of the second black hole. It dives, as it were, into the accretion disk of its neighbor in the system, and at this moment an energy release occurs. A similar flash is recorded in the process of “emergence” from the other side. It’s like a sword dance or laser sword dance, to use comparable terms, when two partners circle one around the other in an orbital dance and clash with disc swords.
The binary system of black holes in OJ 287 turned out to be even more interesting than scientists imagined. Observations of this object will continue. It can be expected that scientists will also try to follow it with the help of gravitational detectors. This will provide even more data on the physics of processes that we will never be able to reproduce in terrestrial laboratories.
