A new physical model combines observations and simulations and explains key processes in the vicinity of black holes — from jet emissions to extreme mass growth
Astronomers studying the supermassive black hole M87* discovered a new way in which these cosmic monsters release their energy.
From a "starless nebula" to a giant galaxy
For nearly two centuries, astronomers were unsure of the true nature of the bright object in the Virgo constellation that Charles Messier recorded in 1784 as “87: a starless nebula.” What appeared to be a fuzzy patch of light was later revealed to be a giant galaxy. When a mysterious jet of light was discovered emanating from its center in 1918, scientists had no idea what could have created it.
At the core of this massive galaxy, now named M87, is the supermassive black hole M87*, which contains a mass about six and a half billion times that of the Sun. This black hole is spinning rapidly, and its rotation drives a stream of charged particles that shoots out at nearly the speed of light, extending about 5,000 light-years into space. Similar jets are seen around other spinning black holes, helping to spread energy and matter throughout the universe and shape the evolution of galaxies.
Cracking the code of black hole energy
A research team from Goethe University Frankfurt, led by Prof. Luciano Razzola, has developed a new computational tool called FPIC. This simulation program precisely simulates how a spinning black hole converts its rotational energy into a powerful jet. The researchers discovered that in addition to the well-known Blandford-Zenaik mechanism, which has long been considered the explanation for how black holes extract rotational energy using magnetic fields, another important process also plays a role: magnetic fusion. In this phenomenon, magnetic field lines break and rejoin, converting magnetic energy into heat, radiation and plasma bursts.
Using the FPIC program, the team simulated the behavior of countless charged particles and extreme electromagnetic fields affected by the intense gravity around a black hole. Dr. Claudio Maringolo, the program's lead developer, explained: "Simulating such processes is critical to understanding the complex dynamics of relativistic plasmas in curved space-time near compact bodies, which are governed by the interplay between extreme gravitational and magnetic fields."
Running these simulations required extraordinary computing resources, amounting to millions of processor hours on the Goethe supercomputer in Frankfurt and the Netz supercomputer in Stuttgart. This enormous computing power was needed to solve Maxwell's equations and the equations of motion of electrons and positrons within the framework of Albert Einstein's general theory of relativity.
Plasma chains and negative energy
In the equatorial plane of the black hole, the researchers' calculations revealed intense fusion activity, which causes the formation of a chain of plasmoids - condensations of plasma into energetic "bubbles" - that move at almost the speed of light. According to the scientists, this process is accompanied by the creation of particles with negative energy that are used to drive extreme astrophysical phenomena such as jets and plasma eruptions.
"Our results open up the fascinating possibility that the Blandford-Zenaik mechanism is not the only astrophysical process that can extract rotational energy from a black hole," says Dr. Filippo Camioni of the FPIC project, "but that magnetic fusion also contributes."
Lighting up the brightest engines in the universe
“With our research, we can show how energy is efficiently extracted from spinning black holes and harnessed to jets,” says Razzola. “This allows us to help explain the extreme luminosity of active galactic nuclei and also the acceleration of particles to almost the speed of light.” He adds that it is very exciting and fascinating to better understand what happens near a black hole using sophisticated numerical programs. “At the same time, it is even more rewarding to be able to explain the results of these complex simulations through careful mathematical treatment – as we have done in our study.”
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This provides a solid foundation for understanding the subject.