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New simulations give hints on how to escape a black hole



  How to Escape a Black Hole

This visualization of a general relativistic collisionless plasma simulation shows the density of positrons near the event horizon of a rotating black hole. Plasma instabilities produce island-like structures in the area of ​​high electric current. (Credit: Kyle Parfrey et al / Berkeley Lab)

Black holes are known for their voracious appetite, which acts with such force on matter that not even light can escape when swallowed.

Less understood, however, is how black holes consume energy that is blocked in their rotation, and propel plasmas into near-light-speed opposite sides in one of the universe's mightiest displays. These jets can span millions of light years.

New simulations, led by researchers from the US Department of Energy's (Berkeley Lab) Lawrence Berkeley National Laboratory (Berkeley Lab) and UC Berkeley, combine decades of theories to provide new insights into the driving mechanisms of plasma jets they can steal energy from the strong gravitational fields of the black holes and drive them away from their gaping mouths.

The simulations could provide a useful comparison for high-resolution observations of the Event Horizon Telescope, an array designed to provide the first direct images of the regions in which the plasma jets form.

The telescope will allow new views of the black hole in the center of our own Milky Way as well as detailed views of other supermassive black holes.

"How can the energy from the rotation of a black hole be extracted to create nozzles?" Said Kyle Parfrey, who led the simulation work while an Einstein Postdoctoral Fellow at the Berkeley Lab's Nuclear Science Division. "This has long been a question."


This simulation shows a rotating black hole (below) and a collisionless plasma jet (top). The simulation shows the densities of electrons and positrons as well as magnetic field lines. The black surface of the black hole, in which all particles must rotate in the same direction as the hole, is shown in green. (Credit: Kyle Parfrey et al / Berkeley Lab)

Now a senior associate at NASA's Goddard Space Flight Center in Maryland, he is the lead author of a study published on January 23 in Physical Review Letters Details of simulation research.

The simulations unite for the first time a theory that explains how electric currents around a black hole form magnetic fields into jets, with a separate theory explaining how particles can pass through the point of a no return – the event horizon – to a distant observer to transport negative energy and reduce the rotational energy of the black hole.

It's like eating a snack that causes you to lose calories instead of gaining them. The black hole actually loses mass when these "negative energy" particles are rubbed.

Computer simulations have difficulty in modeling the complex physics involved in starting the plasma jet, which accounts for the formation of pairs of electrons and positrons, the mechanism of acceleration of particles, and the emission of light in the jets.

The Berkeley Lab has contributed much to plasma simulations in its long history. Plasma is a gas-like mixture of charged particles, which is the most common state of the universe.

Parfrey said he realized that more complex simulations describing the jets require a combination of expertise in plasma physics and the general theory of relativity.

"I thought it would be a good time to bring these two things together," he said.

NASA's Ames Research Center supercomputing center in Mountain View, California has reimaged the simulations with numerical techniques that provide the first model of a collisionless plasma in which collisions between charged particles do not play a major role in the presence of a strong collision Gravitational field in connection with a black hole.

The simulations usually generate the as Blandford-Znajek mechanism, which describes the rotating magnetic fields that form jets, and a separate Penrose process that describes what happens when negative energy par the particles are from the black Hole swallowed.

The Penrose Process: "While this may not necessarily help extract the rotational energy of the black hole," said Parfrey, "it may be directly related to the electric currents that spin the magnetic fields of the jets.

Although Parfrey was more detailed than some earlier models, he noted that his team's simulations still fit in with observations and are somewhat idealized to simplify the calculations needed to perform the simulations. 19659004] The team intends to better model the process by which electron-positron pairs are generated in the jets in order to more realistically study the plasma distribution of the jets and their radiation emission for comparison with observations. They also intend to extend the scope of the simulations to the event horizon of the black hole, the so-called accretion flow.

"We hope to deliver a more unified picture of the entire problem," he said

Other participants in the research include Alexander Philippov, an Einstein Postdoctoral Fellow at UC Berkeley, and Benoit Cerutti, a CNRS researcher at the University Université Grenoble Alpes in France. Parfrey and Philippov were members of the Department of Astronomy and Theoretical Astrophysics at UC Berkeley, and Philippov is now at the Flatiron Institute in New York.

The work was supported by NASA through the Einstein Postdoctoral Fellowships program, CNES, Labex. [email protected] NASA's high-end computing program, TGCC, CINES and the Simons Foundation.

Publication: Kyle Parfrey et al., "First Principles of Plasma Simulation of the Black Hole Start," Physical Review Letters, 2018; doi: 10.1103 / PhysRevLett.122.035101


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