For nearly 200 years, scientists did not realize that the bright patch in the constellation Virgo -- described by Charles Messier in 1781 as "87: Nebula without stars" -- was actually a massive galaxy. Because of this, the strange jet Curtis detected in 1918 remained an enigma for decades.

At the core of this enormous galaxy lies the supermassive black hole M87*, which contains about six and a half billion times the mass of the Sun and spins rapidly. This rotation powers a jet of charged particles traveling almost at the speed of light, extending some 5,000 light-years into space. Jets like this not only release vast amounts of energy and matter into the cosmos but also shape the evolution of galaxies themselves.

Led by Professor Luciano Rezzolla, the Goethe University Frankfurt team has developed a new computational framework called the Frankfurt particle-in-cell code for black hole spacetimes (FPIC). This tool allows scientists to simulate, with exceptional detail, how a black hole's rotational energy is transformed into a relativistic jet. Their research suggests that, alongside the well-known Blandford-Znajek mechanism -- where magnetic fields extract rotational energy from a black hole -- another process plays a major role: magnetic reconnection. In this phenomenon, magnetic field lines snap and reconnect, releasing energy as heat, radiation, and bursts of plasma.

Using the FPIC code, researchers simulated countless charged particles and extreme electromagnetic fields within the intense gravitational pull of the black hole. Dr. Claudio Meringolo, the code's main developer, explains, "Simulating such processes is crucial for understanding the complex dynamics of relativistic plasmas in curved spacetimes near compact objects, which are governed by the interplay of extreme gravitational and magnetic fields."

Running these simulations required immense computational power -- millions of CPU hours on Frankfurt's "Goethe" supercomputer and Stuttgart's "Hawk." This processing capacity was vital to solve Maxwell's equations and the motion of electrons and positrons within the framework of Einstein's general relativity.

The team's calculations revealed vigorous magnetic reconnection in the black hole's equatorial region, creating a chain of plasmoids -- clumps of plasma resembling energetic "bubbles" -- that travel at nearly light speed. The simulations also showed that this activity produces particles with negative energy, which help drive extreme astrophysical events such as jets and plasma eruptions.

"Our results open up the fascinating possibility that the Blandford-Znajek mechanism is not the only astrophysical process capable of extracting rotational energy from a black hole," says Dr. Filippo Camilloni, who also worked on the FPIC project, "but that magnetic reconnection also contributes."

"With our work, we can demonstrate how energy is efficiently extracted from rotating black holes and channeled into jets," says Rezzolla. "This allows us to help explain the extreme luminosities of active galactic nuclei as well as the acceleration of particles to nearly the speed of light." He adds that it is incredibly exciting and fascinating to better understand what happens near a black hole using sophisticated numerical codes. "At the same time, it is even more rewarding to be able to explain the results of these complex simulations with a rigorous mathematical treatment -- as we have done in our work."

• RELATED TOPICS
  • Space & Time
    • Black Holes
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    • Nebulae

• RELATED TERMS
  • Galaxy
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  • Large-scale structure of the cosmos
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