Rosetta Stone for Active Galactic Nuclei

Rosetta Stone for Active Galactic Nuclei

Artistic vision of the central region of the active galaxy OJ 287 with the preceding jet. Precession can be caused by a double black hole (A) or an incorrectly aligned accretion disk (B)

Galaxy OJ 287 with a supermassive black hole has caused a lot of questions in the past. The released rays from this object cover a wide range - from radio to the highest energies in TeV mode. The potential periodicity in the variable optical radiation has made this galaxy a candidate for placing a supermassive double black hole in its center. Thus, we get a kind of Rosetta stone for active galactic nuclei with a hint that this case can act as a prototype and help decipher the fundamental properties of active black holes in general.

An international team of astronomers revealed that the active galactic core in OJ 287 generates a smoothly precessing jet for 22 years. The precession of the observed jet can also explain the variability of the radiation of the galaxy.

Where does the comparison with the Rosetta stone come from? Egyptian hieroglyphs remained a mystery for a long time. It was possible to get the key only in 1799, when they found the Rosetta stone, on which one text was displayed in three languages, among which was the already known ancient Greek. This allowed to learn Egyptian literacy and understand the whole culture. Now the decoding of the galactic jet was also carried out with the help of a key, which was served by a blazar (active galactic nuclei with a feeding supermassive black hole). Galaxy OJ 287 lives at a distance of 3.5 billion light years and can accommodate at least one supermassive black hole, which by mass exceeds a solar one billion times. It is active and releases jets — a plasma stream that forms in the central nuclear region near the central black hole. It can be observed in the airwaves.

But decades of radio observations of various sources of jets still have not brought clear information about the phenomenon. Traditionally, changes in jet brightness were explained by the mechanism of its feeding by the central black hole system. But the moving features in the jet (knots) were associated with blows moving in it. Previously, no one could find the connection between these two phenomena.

The researchers decided to follow the OJ 287 jet near its launch site near the central black hole. Radio interferometry includes radio telescopes across the planet and forms a gigantic mechanism that provides unprecedented resolution. Having studied the data, it was possible to show that both phenomena have the same origin - jet motion. That is, this jet precesses (causes a change in Doppler increase when the angle of view changes).

The team is convinced that this scenario can be applied to the 130-year period of source burning. But additional observations will be required. While still trying to understand the origin of the precession of the jet. This is a physical process, which is also known on Earth. The rotational axis of the planet is devoid of stability, but rotates with a period of 26,000 years due to the tidal influence of the Sun and the Moon. For the precession of the jet indicated two options. There may be a system of two supermassive black holes with a jet from a disk, forced to oscillate by the tidal forces of the second hole. Or is it a single black hole that is tidal in contact with an inconsistent accretion disk. In any case, these conclusions can be used to understand other extragalactic jets.

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