Scientists uncover hidden energy mechanism in M87 black hole
Astrophysicists at Goethe University Frankfurt have simulated how the supermassive black hole M87* powers its massive particle jet using a new numerical code. Their findings reveal that magnetic reconnection, alongside the traditional Blandford-Znajek mechanism, extracts rotational energy from the black hole. This discovery explains the immense jets that influence galaxy evolution.
The supermassive black hole M87*, located at the center of the galaxy M87, has a mass of six and a half billion solar masses and spins rapidly on its axis. It powers a particle jet expelled at nearly the speed of light, extending 5,000 light-years. Such jets disperse energy and matter across the universe and shape galaxies.
A team led by Prof. Luciano Rezzolla at Goethe University Frankfurt developed the Frankfurt particle-in-cell code for black hole spacetimes (FPIC). This code simulates the conversion of rotational energy into particle jets with high precision. The simulations show that, in addition to the Blandford-Znajek mechanism—which extracts energy via strong magnetic fields—magnetic reconnection plays a key role. In this process, magnetic field lines break and reassemble, converting magnetic energy into heat, radiation, and plasma eruptions.
The FPIC code modeled the evolution of charged particles and electromagnetic fields under the black hole's gravity, solving Maxwell's equations and equations of motion for electrons and positrons per Einstein's general relativity. These computations required millions of CPU hours on the "Goethe" supercomputer in Frankfurt and the "Hawk" in Stuttgart.
In the black hole's equatorial plane, the simulations revealed intense reconnection activity forming chains of plasmoids—energetic plasma bubbles—moving at nearly light speed. This generates particles with negative energy, powering jets and eruptions.
Dr. Claudio Meringolo, the code's main developer, stated: "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."
Dr. Filippo Camilloni added: "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, but that magnetic reconnection also contributes."
Prof. Rezzolla explained: "With our work, we can demonstrate how energy is efficiently extracted from rotating black holes and channeled into jets. 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."
The research builds on historical observations: In 1781, Charles Messier described M87 as a "nebula without stars," and its jet was discovered in 1918. The findings are published in The Astrophysical Journal Letters (2025; 992 (1): L8).