LHAASO Observatory Detects Record Gamma Rays from Milky Way Binary System LS I +61° 303

Discover how the LHAASO observatory found 100 TeV gamma rays in the LS I +61° 303 system, proving binary stars act as extreme galactic particle accelerators.

By: AXL Media

Published: May 1, 2026, 11:06 AM EDT

Source: Information for this report was sourced from EurekAlert!

A Galactic Breakthrough in High-Energy Astrophysics

The Large High Altitude Air Shower Observatory, known as LHAASO, has successfully captured ultra-high-energy gamma rays from the binary system LS I +61° 303, marking a significant milestone in the study of the extreme universe. According to the research team led by the Institute of High Energy Physics of the Chinese Academy of Sciences, these emissions were recorded at levels surpassing 100 trillion electron-volts. This measurement represents a dramatic escalation from previous observations of the same system, which had only tracked energy levels reaching approximately 10 TeV. The detection confirms that certain celestial structures within our own galaxy are far more powerful than prior theoretical models suggested.

The Mechanics of a Natural Cosmic Laboratory

This specific binary system is comprised of a massive star locked in orbit with a compact companion, which could be either a stellar-mass black hole or a neutron star. While science has long recognized gamma-ray binaries as potential sites for particle acceleration, only a small number have been confirmed to emit very-high-energy radiation. By leveraging the sensitivity of the LHAASO equipment, scientists were able to monitor the energy spectrum up to 200 TeV. The study highlights that these binaries serve as unique natural laboratories, allowing researchers to observe physics under conditions of extreme density and gravity that cannot be replicated in any facility on Earth.

Deciphering the Rhythms of Orbital Modulation

One of the most striking aspects of the discovery is the variation in brightness, or flux, which synchronizes with the orbital period of the stars. The researchers observed that the gamma-ray intensity fluctuates over a cycle of roughly 26.5 days, a phenomenon known as orbital modulation. According to the collaborative report, this modulation is energy-dependent, hinting at a highly complex internal environment where physical processes shift as the two stars interact. This rhythmic pulsing of high-energy light provides a roadmap for understanding how the proximity of a compact object to a massive star influences the acceleration of surrounding particles.