Chinese scientists discover new extreme particle accelerator in cosmos – Xinhua

Researchers using the Large High Altitude Air Shower Observatory (LHAASO) in China have identified a new extreme particle accelerator within the Milky Way. The discovery centers on a binary star system that has accelerated particles beyond the 100 tera-electronvolt (TeV) energy barrier.

This finding is significant for astrophysics because it identifies a source of ultra-high-energy cosmic rays that differs from the traditionally suspected origins. While supernova remnants have long been the primary candidates for such acceleration, this discovery suggests that binary star systems can also function as PeVatrons.

A PeVatron is a cosmic accelerator capable of boosting particles to peta-electronvolt (PeV) energy levels, which is one quadrillion electronvolts. Identifying these sources is a primary goal for scientists attempting to understand the origin and mechanism of the most energetic particles in the universe.

Breaking the 100 TeV Barrier

The detection of gamma rays exceeding 100 TeV from a single source provides direct evidence of particle acceleration at extreme scales. In the case of the newly discovered binary star system, the energy levels observed rewrite previously held limits on how particles are accelerated within such systems.

Binary systems typically consist of two stars orbiting a common center of mass, often involving a compact object such as a neutron star or a black hole. The interaction between these objects, including the accretion of matter and the generation of intense magnetic fields, creates the conditions necessary to propel particles to relativistic speeds.

The LHAASO data indicates that the acceleration process in this specific binary system is efficient enough to push particles past the 100 TeV threshold, a feat previously thought to be reserved for the most violent events in the cosmos, such as the collapse of massive stars.

The Role of the LHAASO Observatory

The discovery was made possible by the technical capabilities of the Large High Altitude Air Shower Observatory, located in the mountains of Tibet. The facility is designed to detect very-high-energy gamma rays and cosmic rays by observing the air showers they create when they hit the Earth’s atmosphere.

LHAASO utilizes a combination of detection methods to ensure accuracy, including:

• Water Cherenkov detectors that measure the timing and density of particles in an air shower.
• Scintillator detector arrays that provide precise measurements of the shower core.
• Wide-field-of-view muon detectors that help distinguish between gamma rays and hadronic cosmic rays.

The high altitude of the observatory reduces the amount of atmospheric interference, allowing the facility to capture high-energy photons that would otherwise be absorbed before reaching lower-elevation telescopes.

Impact on Cosmic Ray Theory

For decades, the scientific community has sought to locate the PeVatrons within our own galaxy to explain the observed spectrum of cosmic rays. The identification of a binary star system as an extreme accelerator suggests that the population of PeVatrons in the Milky Way is more diverse than previously modeled.

This discovery implies that the acceleration mechanisms in binary systems—likely involving shock waves from stellar winds or relativistic jets from a compact companion—are more powerful than earlier theoretical limits suggested.

By analyzing the energy distribution of the particles emitted by this source, researchers can now better calibrate their models of how magnetic fields and plasma interactions function in extreme environments.

The findings published on May 9, 2026, provide a new benchmark for the American Physical Society and other global research bodies to evaluate the contribution of binary systems to the overall cosmic ray flux of the galaxy.