New simulations reveal black-hole jet ignition secrets

Simulation snapshot showing electron and antielectron pair creation

Jets, which are powerful collimated outflows, are routinely observed as being launched from black holes, yet their origin has remained elusive for decades. New computer simulations reveal for the first time the mechanisms of their ignition. These results have been published in the Physical Review Letters on April 6th 2020.




It has long been thought that the rotation of the black hole is the source of jet power, acting like an electric motor driving currents. However, how the plasma carrying these currents is generated has long been puzzling, because the region surrounding the black hole is quickly cleared away of matter.

We have been able to pinpoint where and how this plasma is created. Matter that lies too close is swallowed by the black hole due to its extreme gravity while plasma in the jet is ejected outwards. We discovered a "watershed" in between the two, that separates inflow and outflow. We have shown that plasma is generated in this region, as pairs of electrons and positrons are created due to the intense radiation field surrounding the black hole. Such intense plasma creation is necessary for the black hole to sustain the jet.

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

Figure caption: Simulation snapshot showing electron and antielectron pair creation (density on the right panel) via the annihilation of high-energy gamma-ray photons (density on the left panel) around a rapidly rotating black hole (black disk). Black-hole jet ignition happens along the white solid line, the analog of a watershed on Earth.

Simulation snapshot showing electron and antielectron pair creation (density on the right panel) via the annihilation of high-energy gamma-ray photons (density on the left panel) around a rapidly rotating black hole (black disk). Black-hole jet ignition happens along the white solid line, the analog of a watershed on Earth.
Reference

Multidimensional Simulations of Ergospheric Pair Discharges around Black Holes, Benjamin Crinquand, Benoît Cerutti, Alexander Philippov, Kyle Parfrey, and Guillaume Dubus Phys. Rev. Lett. 124, 145101 – 6 April 2020
DOI

Local scientific contacts:

– Benjamin Crinquand | IPAG | benjamin.crinquand [at] univ-grenoble-alpes.fr
– Benoît Cerutti | IPAG | benoit.cerutti [at] univ-grenoble-alpes.fr
– Guillaume Dubus | IPAG | guillaume.dubus [at] univ-grenoble-alpes.fr

Publié le 21 avril 2020