Signs of a double supermassive black hole in a distant galaxy

THE galaxy OJ 287 it is not an ordinary object. belongs to the group of blazars, the most powerful sources of continuous radiation in the universe. These objects show a central supermassive black hole surrounded by a disk of gas that feeds it, but they are among the 10% of galaxies we call active and among the even smaller percentage that have a jet of matter emerging from both poles at very high levels. speed and that we see almost straight ahead.

Furthermore, OJ 287 is the only binary supermassive black hole candidate that we know in our cosmic neighborhood.

Now, an international scientific team led by the Institute of Astrophysics of Andalusia (IAA-CSIC) has obtained the high resolution image of the central regions of OJ 287, which suggests that we are indeed looking at a unique pair of black hole dancers.

Data analysis revealed that this spectacular fountain presents a highly curved plasma jet which has several nodes, or brighter regions, the nature of which is unknown.

Comparison of space and ground observations revealed a progressive curvature of the jet with increasing angular resolution, consistent with theoretical predictions that OJ 287 hosts not one, but two supermassive black holes, with the secondary orbiting the primary and drilling through its accretion disk twice every twelve years.

Furthermore, the team found that while the energy in the jet’s inner regions arises from plasma particles, at greater distances it comes from both the particles and the local magnetic field. They also found evidence that the magnetic field, in the innermost regions, it is coiled, in a helical structure that agrees with the jet formation models.

“These results represent an advance in our knowledge of jet morphology in the vicinity of the mid-engine. They also confirm the role of magnetic fields in its launch and once again record indirect evidence of the existence of a binary black hole system at the heart of OJ 287.” Thalia Traianou, a researcher at the IAA who participated in the work.

Telescope observations on the ground and in space

The discovery was made possible thanks to the technique known as Very long baseline interferometry (VLBI) by the acronym in English), which allows multiple radio telescopes geographically separated to work in unison, functioning as a telescope with a diameter equivalent to the maximum distance that separates them.

In this case, the science team observed OJ 287 with antennas on the ground and in space. The participation of Spektr-R ten-meter orbital antenna (RadioAstron Mission, from the Astro Space Center in Moscow and supported by the Russian Space Agency), allowed the creation of a radio telescope with a diameter fifteen times greater than that of Earth.

The resulting image is equivalent to distinguishing a dime on the surface of the Moon from the ground. “We’ve never analyzed the inner workings of the jet on OJ287 in such detail,” notes Traianou.

Observing arrays and images of the curved jet in the active galaxy OJ 287. From top to bottom, a global array of radio telescopes, including the Spektr-R space observatory, which allowed a record observation of 0.012 milli arcseconds; millimeter wavelength observations from the Global mm-VLBI Array; and the American NRAO’s Very Long Baseline Array. / Gomez et al./The Astrophysical Journal

To date, one of the main unknowns related to the formation of supermassive black holes is known as final analysis problem.

The theory suggests that all binary black hole systems will forever maintain a distance of about one parsec (one parsec equals 3.26 light-years), due to the difficulty in dissipating angular momentum when the two black holes are isolated. from other gravitational interactions. , and the separation between them is not small enough for them to emit gravitational waves. The detection and study of the gravitational waves emitted by these systems can confirm or rule out this theory.

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