Sagittarius A*, the supermassive black hole at the center of the Milky Way, can accelerate protons to petaelectronvolt energies through the magnetic Penrose process. These charged particles reach energy levels 1,000 times higher than the fastest protons generated inside the Large Hadron Collider, turning the galactic core into an active cosmic PeVatron.
A numerical modeling study led by astrophysicist Marina Cermeño demonstrated that rotating black holes can directly transfer rotational energy to particles inside their ergosphere under an ultra-high efficiency regime. “The magnetic Penrose process (MPP) is one of the most efficient mechanisms for extracting rotational energy from a magnetized Kerr black hole (BH), enabling charged particles to reach very-high energies,” the researchers stated in the paper registered under identifier arXiv:2609.04051.
Sagittarius A* transfers rotational energy through neutron decay
Astrophysicists have traditionally viewed the accretion disk and relativistic jets of supermassive black holes as their primary power sources, heating surrounding plasma through magnetic friction and gravitational compression. The new investigation examines a direct extraction channel where energy comes from the rotational inertia of the black hole itself, decreasing its total mass without requiring matter accumulation.
According to the calculations submitted on September 3, 2026, neutral particles such as neutrons produced within the accretion flow enter the ergosphere of Sagittarius A*. Inside this region, neutral particles undergo beta decay, breaking down into protons, electrons, and antineutrinos. Because the decay products carry electric charges, they couple immediately to the intense magnetic fields threading the spacetime envelope.
The proton receives an energy kick while the lighter decay products carry negative energy relative to an observer at infinity, falling past the event horizon. This dynamic allows the proton to overcome the immense gravitational pull of Sagittarius A* and escape into surrounding space at velocities approaching the speed of light.
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Technical metrics of the Sagittarius A* particle acceleration study
- Maximum particle energy: 1 PeV (10^15 electron-volts), which is 1,000 times greater than maximum Large Hadron Collider proton collisions
- Physical mechanism: Magnetic Penrose Process operating in an ultra-high efficiency regime driven by neutron beta decay
- Scientific manuscript identifier: arXiv:2609.04051, submitted by lead researcher Marina Cermeño
- Foundational theoretical framework: Roger Penrose rotational energy extraction model formulated in 1969 and expanded in 1971
Physics of frame dragging around the Kerr black hole
The operational engine behind this acceleration is frame dragging, a consequence of Albert Einstein’s general theory of relativity described by the Kerr metric for spinning black holes. In this regime, the rotating mass drags the fabric of space-time along with its spin, creating an outer boundary called the ergosphere located outside the event horizon.
Astrophysicist Brian Koberlein analyzed the implications of the finding on Monday, October 5, 2026. “As a black hole rotates, it drags space around it. This frame dragging effect is most powerful very close to the black hole,” Koberlein stated, explaining that within the ergosphere, physical matter cannot remain stationary relative to a distant observer, regardless of its thrust or velocity.
British mathematical physicist Roger Penrose originally proposed in 1969 that an object splitting into two fragments within the ergosphere could yield an escaping piece with more total energy than the original parent body, with the formal paper published alongside Robert Floyd in Nature Physical Science in 1971. While the classical mechanical version of the Penrose process offers modest energy gains, introducing strong magnetic fields significantly elevates the efficiency, allowing charged subatomic particles to gain massive acceleration kicks.
Central Molecular Zone collisions generate multimessenger signatures
Once accelerated protons break free from the ergosphere of Sagittarius A*, they travel directly into the dense gas clouds of the Central Molecular Zone, which spans hundreds of light-years across the core of the Milky Way. When these relativistic protons collide with ambient gas molecules, the resulting hadronic interactions trigger cascades of secondary particles.
These subatomic collisions produce gamma rays bearing specific spectral signatures alongside relativistic neutrinos. Ground-based Cherenkov observatories, including the High Energy Stereoscopic System and the High-Altitude Water Cherenkov facility, have previously detected diffuse high-energy gamma-ray emissions originating from the galactic center, though the precise acceleration mechanism behind those emissions has remained unresolved among astrophysicists.
Because neutron beta decay produces neutrinos simultaneously with protons, and subsequent hadronic collisions generate secondary neutrinos, the entire mechanism yields a distinct multimessenger signal. Astronomers tracking both high-energy light and elusive neutral leptons can evaluate the signature to test whether the magnetic Penrose process is operating in real time.
Detection limits and next-generation neutrino observatories
Direct experimental confirmation of neutrinos and gamma rays carrying the exact signatures predicted by the model has not yet occurred. Current terrestrial detectors lack the sensitivity required to isolate the faint multimessenger stream produced by Sagittarius A* above the general cosmic-ray background.
Observational confirmation will depend on upcoming and expanding particle astrophysics facilities. Upgraded installations, including the IceCube-Gen2 observatory located in Antarctica, the KM3NeT/ARCA array deployed in the Mediterranean Sea, the Southern Wide-field Gamma-ray Observatory, and the Cherenkov Telescope Array Observatory, are designed to attain the angular resolution and energy thresholds needed to verify whether Sagittarius A* functions as an active PeVatron.