Chinese satellites and LHAASO confirm high-energy particles can travel directionally tens of light-years

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

Background on Cosmic Rays

Cosmic rays are high-energy particles originating from outer space. Their origins, acceleration, and propagation have long been puzzles in astrophysical research. 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.

How Cosmic Rays Are Detected

According to Feng Hua, a researcher at the Institute of High Energy Physics of the Chinese Academy of Sciences, high-energy particles moving through magnetic fields produce synchrotron radiation. A portion of this radiation, in the form of X-rays, is detected by the "Tianguan" satellite. At the same time, these high-energy particles interact with low-energy photons in space, generating ultra-high-energy gamma rays that can be detected by LHAASO.

Previous Observations and New Findings

Earlier international observations had revealed an X-ray tail several light-years long surrounding 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.

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

Significance of the Discovery

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

More importantly, this study combines 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.

Future Prospects

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