Visualization of general-relativistic simulation of collagen-free plasma. Image: Parfrey / LBNL
Researchers have used one of the most powerful supercomputers in the world to better understand how high-energy plasma jets escape the intense gravity of the black hole, which dries everything else in their path – including light.
Before stars and other matter pass the black hole without a return – the border known as the "horizon horizon" – and they are consumed in the black hole, they move to the rotation of the black hole. The issue that has been troubled by physicists for decades has been that some energy has managed to escape the process and focus on the plasma streams that travel through space near the speed of light.
As detailed in the paper published last week in Physical Review LettersScientists connected to the Energy Department and the California University of Berkeley used a supercomputer at Lawrence Berkeley National Laboratory to simulate plasma jet jets, electrically charged substances similar to gas.
The simulations finally reconciled two decades old theories that are trying to explain how energy can be extracted from the rotating black hole.
The first theory describes how electric currents around the black holes flutter their magnetic field to create a jet, known as the Blandford-Znajek mechanism. This theory assumes that the material that is caught in the gravitational black rotating horn will be magnetized as it approaches the horizon of the event. The black hole acts as a massive conductor that rotates in a large magnetic field, which will cause a difference in the energy (voltage) between the poles of the black hole and its equator. This difference of energy then sprays as nozzles on the poles of the black holes.
The other theory was described by the Penrose process, in which the particles approaching the horizontal horizon of the black hole separated. In this scenario, one half of the particle comes out of the black holes, and the other half of the particle carries negative energy and falls into the black hole.
"There is an area around a rotating black hole, called ergosphere, within which all particles are forced to rotate in the same direction as the black holes," Kyle Parfrey, principal author of the work and theoretical astrophysicist at NASA, told me at the e-mail. "In this region it is possible that a particle in a given sense effectively has a negative energy if it tries to circle around the rotation of the holes."
In other words, if one half of the split particles starts to rotate the black hole, this will reduce the angular momentum or rotation of the black hole. But that rotational energy has to go somewhere. In this case, it converts into the energy that drives the other half of the black hole particles.
According to Parfrey, the Penrose process observed in their simulations was slightly different from the classic splitting particle described above. Instead of particle cleavage, the electrically charged particles in the plasma act on electromagnetic forces, some of which run against the rotation of the black holes on the path of negative energy. In that sense, Parfrey told me that they still considered the type of Penrose's process.
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Amazing part of the simulation, Parfrey told me, was to seem to establish the link between the Penford process and the Blandford-Znajek mechanism that had never been seen before.
To create magnetic fields that extract energy from the black holes in the Blandford-Signal Mechanism, electrical power is carried by particles inside the plasma and a significant number of these particles have a negative energy characteristic characteristic of the Penrose process.
"So it seems that, at least in some cases, these two mechanisms are connected," Parfrey said.
Parfrey and his colleagues hope that their models will provide the most necessary context for the photography of the Event Horizon telescope, a series of telescopes aimed at displaying directly the horizon of events where these plasma jets emerge. However, as long as this first image was not produced, Parfery said he and his colleagues wanted to improve these simulations to better adapt to the existing observations.