Multidimensional simulations reveal how black holes discharge powerful jets of plasma

On the  April 14, 2020
It is common to observe jets of matter being produced and propelled near supermassive black holes. However, this phenomenon has eluded our understanding for decades. New state-of-the-art numerical simulations reveal for the first time their ignition mechanism as close to the black hole horizon as possible. These results were recently published in a Physical Review Letters article on 6 April 2020.

It is commonly accepted that the rotation of the black hole is at the origin of the jet's power. An analogy can be made with a dynamo, whose rotation would produce an electric current. However, where and how the electric charges conducting this current are generated has long remained a mystery. The environment near the black hole is quickly emptied of all matter.

Our team has determined precisely where the creation of matter takes place. Matter that is too close to the black hole falls into it because of its strong gravity. Conversely, the matter in the jet is ejected outward. So there is a "watershed" between the two, separating the flows going towards and away from the black hole. We have shown that an intense creation of matter and antimatter takes place at this surface, through the annihilation of high-energy photons emitted by these particles. This allows the jet to be continuously supplied with matter and to conduct the current.

These simulations could help to interpret recent images of the shadow of the M87* black hole, and more generally to understand the origin of supermassive black hole jets.

Image de sortie d’une simulation montrant la création d'électrons et d'antiélectrons (densité cadrant de droite) par l’annihilation de photons gamma de haute énergie (densité cadrant de gauche) autour d’un trou noir en rotation rapide (disque noir). L’allumage du jet du trou noir se réalise le long de la ligne blanche, l’équivalent d’une « ligne de partage des eaux » sur Terre.
Figure 1: Output image of a simulation showing the creation of electrons and anti-electrons (right framing density) by the annihilation of high-energy gamma photons (left framing density) around a rapidly rotating black hole (black disc). The jet of the black hole is ignited along the white line, the equivalent of a "watershed" on Earth.
Published on  April 14, 2020
Updated on April 16, 2020