Science and Technology Daily, Nanjing, October 20 (Reporter Jin Feng) The dark matter particle detection satellite "Wukong" has discovered a new mystery in the universe!
This time, its discovery challenges the classical model of cosmic ray propagation.
The English version of my country's comprehensive academic journal "Science Bulletin" recently published a new result of the "Wukong" international cooperation group. The researchers used satellite observation data from 2016 to 2021 to analyze and obtain 10 billion electron volts per nucleus ( Accurate measurements of boron/carbon (B/C) and boron/oxygen (B/O) ratios in cosmic rays ranging from 10 GeV/n) to 5.6 trillion electron volts per nucleus (5.6 TeV/n), and A new structure of the energy spectrum was discovered.
"'Wukong' found with high confidence for the first time that in the energy range above about 100 billion electron volts per nucleus (100 GeV/n), the B/C and B/O in cosmic rays decrease as the energy of cosmic ray particles increases The trend of , which means that the classic cosmic ray propagation model needs to be modified." On October 20, Yuan Qiang, one of the authors of the paper and a researcher at the Purple Mountain Observatory of the Chinese Academy of Sciences, said in an interview with a reporter from Science and Technology Daily.
Cosmic rays are high-energy particles from outer space, including various atomic nuclei, electrons, high-energy gamma rays, and neutrinos.
In cosmic rays, carbon nuclei, oxygen nuclei, etc. belong to the primary particles produced in the process of stellar nucleosynthesis, while boron nuclei are mainly secondary particles produced after carbon and oxygen nuclei collide with interstellar matter during the propagation process.
Yue Chuan, one of the authors of the paper and an associate researcher at the Purple Mountain Observatory of the Chinese Academy of Sciences, said that if carbon and oxygen nuclei propagate in a dense medium in cosmic rays, there will be a greater probability of fragmentation, resulting in more boron nuclei. Otherwise, the abundance of boron nuclei is low.
Therefore, analyzing the proportion of boron nuclei, carbon nuclei, and oxygen nuclei in cosmic rays is helpful to study the propagation process of cosmic rays.
"This time, the 'Wukong' international cooperation team has achieved the first time in the world to accurately measure B/C and B/O above 1TeV/n. The results show that B/C and B/O deviate significantly in the wide energy range. The behavioral characteristics of a single power-law distribution." Yuan Qiang said that the classical cosmic ray propagation theory believes that the diffusion coefficient of cosmic rays varies with energy in a power-law manner, but this study found that the energy dependence of the diffusion coefficient is more apparent than previously known. complex.
The research team believes that this study is of great significance for revealing the propagation mechanism of cosmic rays and the turbulent properties of the interstellar medium. It also means that the astrophysical background of the indirect detection of dark matter based on antimatter cosmic rays needs to be reassessed.
(Source: Science and Technology Daily)