The reporter learned from the dark matter satellite "Wukong" team on November 1 that based on the "Wukong" data, researchers have recently drawn the highest energy spectrum of boron/carbon and boron/oxygen cosmic ray particles so far, and discovered a new structure of the energy spectrum. . This latest result shows that the propagation of high-energy particles in the universe may be slower than expected.

Cosmic rays are high-energy particles from outer space. Among them, carbon and oxygen nuclei are the primary particles produced in the process of stellar nucleosynthesis, while boron nuclei are mainly secondary particles produced by carbon and oxygen nuclei colliding with interstellar matter during the propagation process. In the first six years of observations, "Wukong" has recorded more than 3.5 million carbon, oxygen, and boron nuclei data, and researchers have accurately mapped 0.01TeV/n to 5.6TeV/n (1TeV/n = 1 trillion electrons). Exact energy spectrum of cosmic ray boron/carbon ratio and boron/oxygen ratio in the volt/nucleon) energy band. At about 0.1TeV/n, the energy spectrum shows a sharp inflection that is different from the theoretical expectation.

Chang Jin, chief scientist of the Dark Matter Satellite and academician of the Chinese Academy of Sciences, introduced that this is the first time that "Wukong" has accurately measured the ratio of secondary/primary particles in cosmic rays. In the energy range above 1TeV/n, the energy spectrum drawn by "Wukong" has the highest accuracy, and "sees" the energy spectrum structure that is different from the expected, which means that the classical cosmic ray propagation model may need to be further revised.

Yue Chuan, a member of the satellite science team and an associate researcher at the Purple Mountain Observatory of the Chinese Academy of Sciences, explained that the inflection in the boron/carbon and boron/oxygen ratios in the high-energy segment may be because the propagation of high-energy particles in the universe is slower than expected. The slower the primary particle travels, the more chance it has to collide with interstellar matter, fragmenting and producing more secondary particles.

"Because the collision products of cosmic ray particles will constitute the background of dark matter detection, this research may also help humans to search for dark matter more precisely." Yue Chuan said.

"Wukong" is my country's first astronomical satellite, launched at the end of 2015. At present, the satellite detectors are still in good condition, and various scientific data are constantly accumulating.

The "Wukong" scientific research team disclosed that at present, the team is carrying out the key technical research of the next-generation dark matter detection project "Very Large Area Gamma-ray Space Telescope (VLAST)". The next-generation space telescope's ability to detect gamma rays will be increased by more than 50 times, which may help humans track the specific traces of dark matter, and can also efficiently study changes in cosmic celestial bodies.

The research results have been recently published in my country's comprehensive academic journal "Science Bulletin" (English version).