2023-06-21 12:00:05
The oldest recorded observation of active galaxy OJ 287 was in 1888, but it didn’t start to receive full attention until regarding a century later, around 1982. As a result of scrutinizing past observation records, it was found that the brightness of OJ 287 changed while two cycles, a 55-year cycle and a 12-year cycle, were intricately intertwined. A detailed observation of the variability that appears in the shorter 12-year cycle reveals that two flashes occur with even shorter intervals. In order to explain such a complicated variation period, a model has been proposed that there are two supermassive black holes forming a binary star at the center of OJ 287.[▲ Figure 1: Imaginary drawing of OJ 287. The secondary revolves around the primary, sometimes penetrating the primary’s accretion disk. This is observed on Earth as a 12-year cycle of light variation (Credit: AAS 2018)】 【▲ Figure 2: Graph showing changes in brightness of OJ 287. Due to the long history of observations, it can be said that long-period variability has also been revealed. It is hypothesized to be a binary supermassive black hole regarding 150 million times more massive. The heavier black hole ‘primary’ is encased in an accretion disk and dominates OJ 287’s radiation. On the other hand, the lighter black hole “secondary” is thought to orbit the primary in a very long elliptical orbit with a period of 12 years. Since there is no fixed name or provisional designation to distinguish the supermassive black holes of OJ 287, many texts refer to the heavier black hole as the primary and the lighter one as the secondary. This article follows suit. Because the orbital plane of the secondary, which orbits in a comet-like orbit, is tilted with respect to the accretion disk, the secondary sometimes crosses the accretion disk. At this time, the material inside the accretion disk is heated, producing a bright flash that lasts for regarding two weeks. It is this process that produces the short 12-year variability period, and the two short flashes can be explained by the secondary crossing the accretion disk twice. On the other hand, the long 55-year variability period is thought to be due to the large change in the orbit of the secondary. The primaries and secondaries exert strong gravitational forces on each other, so the periapsis (the point on the orbit where they are closest to each other) of the secondary’s orbit continues to move significantly. The change associated with this periapsis migration is the 55-year light variation period.[Reference: A video explaining the relationship between changes in the orbit of the secondary and the timing of the observed flash]Although the model that there is a large black hole binary in the center of OJ 287 has been supported for many years, the existence of the secondary has been unacceptable. For a long time there was no evidence to show. OJ 287 is an extremely distant galaxy, regarding 3.5 billion light-years from Earth, and the secondary is very close to the primary, so it was impossible to observe them separately. A research team led by Mauri J. Valtonen of the University of Turku attempted to observe OJ 287 by estimating the exact timing of the predicted 2022 flash, taking into account the theory of relativity. As a result, flashes were observed at the pre-predicted period, but it was found that there was a period of regarding one day during which the brightness increased significantly. This was completely unexpected, and it was observed for the first time that it emits 100 times more radiation than the Milky Way galaxy in a short period of time. As a result of the analysis, it was found that the jet acceleration caused by the sudden inhalation of a large amount of material immediately following the secondary plunged into the primary’s accretion disk was the cause of the short burst of radiation. Since such emissions are difficult to explain without the existence of secondaries, our observations strongly support the existence of OJ 287’s secondaries. Since past data do not record such rapid emissions, it is highly likely that the short-term emissions observed this time were missed by chance. OJ 287’s apparent position on the celestial sphere sometimes approaches the Sun, and not all flashes can be observed. was. As Mr. Valtonen also said, “(It was overlooked until now) just happened to be hit by bad luck.” I was there. The two supermassive black holes at the center of OJ 287 are also attracting attention as binary black holes that are said to emit gravitational waves with extremely long periods. The near-certainty of the existence of the secondaries from this study may strengthen observations with gravitational-wave telescopes. SourceMauri J. Valtonen, et.al. “Refining the OJ 287 2022 impact flare arrival epoch”. (Monthly Notices of the Royal Astronomical Society)Mauri Valtonen. “First Detection of Secondary Supermassive Black Hole in a Well-Known Binary System”. (University of Turku) Lankeswar Dey, et.al. “Authenticating the Presence of a Relativistic Massive Black Hole Binary in OJ 287 Using Its General Relativity Centenary Flare: Improved Orbital Parameters”.
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