Chinese satellites and observatory confirm directional propagation of high-energy particles over tens of light-years

Beijing, September 21 (Xinhua) — A Chinese research team has confirmed that high-energy particles can propagate in an orderly manner over long distances along a specific direction, using joint observations from the "Tianguan" satellite and the Large High Altitude Air Shower Observatory (LHAASO), also known as "Lasso." The findings were published on September 21 in the English edition of the academic journal Science China: Physics, Mechanics & Astronomy.

Collaborative Detection by "Tianguan" and "LHAASO"

Cosmic rays—high-energy particles originating from outer space—have long posed a mystery in astrophysics regarding their origin, acceleration, and propagation. Previously, due to a lack of observational evidence, the scientific community generally assumed that cosmic rays spread randomly in all directions after leaving their acceleration sources.

According to Feng Hua, a researcher at the Institute of High Energy Physics, Chinese Academy of Sciences, high-energy particles moving through magnetic fields produce synchrotron radiation, part of which is detected as X-rays by the "Tianguan" satellite. Meanwhile, these particles also interact with low-energy photons in space, generating ultra-high-energy gamma rays detectable by LHAASO.

Earlier international observations had revealed an X-ray tail several light-years long around the pulsar PSR J1740+1000, located approximately 4,600 light-years from Earth. LHAASO also detected ultra-high-energy gamma-ray radiation near this pulsar. However, because the gamma-ray radiation appeared beyond this "small tail," researchers could not confirm whether both signals originated from the same group of high-energy particles.

Reconstructing Long-Distance Propagation

Leveraging the wide field of view and low noise of the "Tianguan" satellite's X-ray telescope, the research team conducted approximately 70,000 seconds of observation. They discovered that the tail was far longer than previously observed: it extends about 42 light-years from the pulsar toward the southwest, covering the region of ultra-high-energy gamma-ray radiation. This makes it the longest known X-ray pulsar wind nebula tail.

"This confirms that after leaving the pulsar wind nebula, high-energy particles do not always disperse within a short distance. Instead, they can propagate tens of light-years along a specific direction," Feng Hua said. The finding provides new observational evidence for understanding how high-energy particles travel from their accelerating celestial bodies through interstellar space.

More importantly, the study combined observations from two different wavelength bands—X-rays and ultra-high-energy gamma rays—to reconstruct the long-distance propagation process of high-energy particles.

Yuan Weimin, chief scientist of the "Tianguan" satellite and a researcher at the National Astronomical Observatories, Chinese Academy of Sciences, noted that the collaboration between major scientific facilities has begun to address significant fundamental and interdisciplinary scientific questions. He expressed hope for more and greater achievements in the future.

Reporters: Liu Zhen, Li Like, Xinhua News Agency