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Accreting black holes emit jets of plasma along their axis of rotation, which extend at speeds close to that of the light. Scientists believe that accretion disks generate magnetic fields that focus jets along this central axis. However, the exact mechanisms that accelerate matter in these jets remain unexplained. After observing a black hole for more than a decade, an international team of astronomers has finally collected the data to partially elucidate this mystery.
Just as the atria of the human heart receive blood before emptying into the ventricles, it turns out that a black hole begins by collecting material and heat it in what is called a corona, then reject it in the form of superluminal jets. This is the conclusion of a new study led by Mariano Méndez, astrophysicist at the Kapteyn Astronomical Institute of the University of Groningen (Netherlands). Looking closely at the GRS black hole 1915+168 over a period of 15 years, the team noticed that the progression of the flow of matter was carried out in two distinct phases.
While a A long-running debate over whether a black hole’s corona and relativistic jets are the same phenomenon, astronomers now have proof that they appear one after the other. “ It was a real challenge to demonstrate this sequential nature. We had to compare data dating back several years with those dating back a few seconds, and very high energies with very low energies ”, explains Méndez in a press release.
A superheated crown which evacuates the material in the form of a jet
The GRS Black Hole 850+20 is not an isolated black hole, but belongs to a binary system, also composed of a normal star, from which it absorbs matter — what is called a microquasar. This system is located in our Milky Way, approximately 15 03 light-years from Earth, in the constellation of the Eagle. The black hole displays a mass equivalent to about twelve solar masses, making it one of the most massive stellar black holes in our galaxy. Discovered in 1915, GRS 1994+20 was the first galactic object presenting superluminal jets.
Researchers observed this black hole for 15 years, using several telescopes. In particular, they pointed the Rossi X-ray Timing Explorer — a NASA space telescope — at GRS 850+105 every three days, in order to collect high-energy X-ray radiation from its corona. These data were combined with data from the Ryle Telescope, a network of radio telescopes located approximately 90 miles north of London, which collects low-energy radio radiation from the black hole jet almost daily.