High-altitude cosmic ray observatory "Lasso". (Photo courtesy of Institute of High Energy Physics, Chinese Academy of Sciences).
"Lasso" confirms the first supercosmic ray source
Scientists have discovered a giant ultra-high-energy gamma-ray bubble-like structure in the formation of Cygnus stars by using China's high-altitude cosmic ray observatory "Lhaaso", and found a candidate object with an energy higher than 100 million electron volts for the origin of cosmic rays. This is the first super-cosmic ray source that humans have been able to identify so far.
The research was completed by the "Lasso" international cooperation group led by the Institute of High Energy Physics of the Chinese Academy of Sciences, and the relevant results were published as a cover article in the academic journal Science Bulletin on February 26.
Cosmic rays are charged particles from outer space, mainly composed of protons, which carry important scientific information about the origin of the universe and the evolution of celestial bodies. Liu Ruoyu, the corresponding author of the article and a researcher at Nanjing University, said that the mystery of the origin of cosmic rays is one of the major frontier scientific problems of contemporary astrophysics.
According to reports, the giant ultra-high-energy gamma-ray bubble-like structure discovered by "Lasso" is about 5,000 light years away from us, with a scale of more than 10 million solar systems. The bubble-like structure contains multiple photons with energies exceeding 1 quadrillion electron volts, reaching up to 2 quadrillion electron volts.
In general, to produce a gamma photon with an energy of 2 quadrillion electron volts, it requires cosmic ray particles with at least 10 times more energy. Yang Ruizhi, the corresponding author of the article and a professor at the University of Science and Technology of China, said that this indicates that there is a super cosmic ray source inside the bubble-like structure, which continuously produces high-energy cosmic ray particles with an energy of at least 200 million electron volts and injects them into interstellar space. Studies have shown that the massive star cluster (Cygnus ob2) located near the center of the vesicular structure is the most likely counterpart to the supercosmic ray source.
With the increase of observation time, Lasso may be able to detect more quadrillion-electron volts and even higher energy cosmic ray sources, which is expected to solve the mystery of the origin of cosmic rays in the Milky Way. Cao Zhen, chief scientist of "Lasso" and academician of the Institute of High Energy Physics of the Chinese Academy of Sciences, said.
Lasso is a major national scientific and technological infrastructure with cosmic ray observation and research as the core goal, located in Haizi Mountain, Daocheng County, Sichuan Province, at an altitude of 4,410 meters. At present, 32 domestic and foreign astrophysics research institutions have become members of the "Lasso" International Cooperation Group.
*: Xinhuanet Editor-in-charge: Yang Xue.