NASA’s planet hunter satellite directly observes smaller objects in a black hole pair for the first time

Several international research groups have already confirmed the theory that there are two black holes at the center of the distant galaxy OJ 287, first proposed by astronomers from the University of Turku, Finland. A new study finds that 2021 satellite observations revealed the smaller black hole of the pair for the first time.

In 2021, NASA’s exoplanet-hunting satellite was aimed at the galaxy OJ 287 to help astronomers confirm the theory initially proposed by researchers at the University of Turku, Finland, of two black holes at the center of the galaxy.

The Transiting Exoplanet Survey Satellite (TESS) is designed to discover thousands of exoplanets orbiting the brightest dwarf stars in the sky. TESS finds planets ranging from small, rocky worlds to gigantic planets, showing the diversity of planets in our Milky Way. So far, 410 confirmed exoplanets or ‘new worlds’ have been found orbiting stars other than the Sun.

In 2021, TESS spent several weeks studying a different kind of system, a distant galaxy called OJ 287. Researchers have found indirect evidence that a very massive black hole in OJ 287 is orbiting a giant black hole 100 times is big.

To verify the existence of the smaller black hole, TESS monitored the brightness of the primary black hole and its associated jet. Direct observation of the smaller black hole orbiting the larger one is very difficult, but its presence was revealed to researchers by a sudden burst of brightness.

Such an event had never been observed before in OJ287, but researcher Pauli Pihajoki from the University of Turku in Finland predicted the event in his dissertation in 2014. According to his thesis, the next eruption is expected to occur in late 2014. 2021, and several satellites and telescopes were pointed at the object at the time.

The TESS satellite detected the expected eruption on November 12, 2021 at 02:00 GMT and the observations were recently published in a study in The Astrophysical Journal by Shubham Kishore, Alok Gupta (Aryabhatta Research Institute of Observational Sciences, India) and Paul Wiita (The College of New Jersey, USA).

The event lasted only 12 hours. This short duration shows that it is very difficult to find a burst of great brightness unless the timing is known in advance. In this case, the theory of the Turku researchers turned out to be correct and TESS was addressed to PB 287 at exactly the right time. The discovery was also confirmed by NASA’s Swift telescope, which was also pointed at the same target.

Furthermore, a large international collaboration led by Staszek Zola of the Jagiellonian University in Krakow, Poland, discovered the same event by using telescopes in different parts of the Earth so that it was always night at at least one of the telescope sites around the world. all day. Moreover, a group from Boston University, USA, led by Svetlana Jorstad and other observers confirmed the discovery by studying the polarization of light before and after the eruption.

In a new study combining all previous observations, Professor Mauri Valtonen and his research team at the University of Turku have shown that the twelve-hour burst of light came from the smaller orbiting black hole and its surroundings. This study was published in The astrophysical diary letters.

The rapid burst of brightness occurs when the smaller black hole “gobbles up” much of the accretion disk surrounding the larger black hole, turning it into an outward gas stream.

The radius of the smaller black hole is then about twelve hours brighter than that of the larger black hole. This makes the color of OJ287 less reddish, or yellow, instead of the normal red. After the eruption the red color returns. The yellow color indicates that we see the light from the smaller black hole over a period of 12 hours. The same results can be derived from other features of the light emitted by OJ287 during the same period.

‘Therefore, we can now say that we have ‘seen’ a spinning black hole for the first time, just as we can say that TESS has seen planets orbiting other stars. And as with planets, it is extremely difficult to get a direct image of the smaller black hole. Because of OJ 287’s great distance, almost four billion light years, it will likely take a very long time before our observation methods are developed enough to even get an image. the larger black hole,” says Professor Valtonen.

‘However, the smaller black hole could soon reveal its existence in other ways, as it is expected to emit nano-Hertz gravitational waves. OJ 287’s gravitational waves should be detectable by the maturing pulsar timing arrays in the coming years,” said A. Gopakumar of the Tata Institute of Fundamental Research in India.