"The scientific research team of the Institute of High Energy Physics of the Chinese Academy of Sciences detected the brightest gamma burst in history based on the ultra-high sensitivity detection system of the high-altitude cosmic ray observatory, injecting new vitality into the exploration of the origin of the universe......" On April 25, the 2024 Zhongguancun Forum Annual Conference with the theme of "Innovation: Building a Better World" opened at the Zhongguancun International Innovation Center. At the opening ceremony, 10 major scientific and technological achievements were released. It is worth mentioning that "Capturing the Cosmic Messenger - 'Lasso' Discovered the Brightest Gamma Burst in History with 10 Trillion Electron Volt Photons" was selected as "Major Scientific and Technological Infrastructure Achievements in a Series of International Leading Achievements".
Located in Haizi Mountain, Daocheng County, Sichuan Province, at an altitude of 4,410 meters, "Lasso" is a one-square-kilometer ground cluster particle detector array composed of 5,216 electromagnetic particle detectors and 1,188 muzi detectors, a 78,000-square-meter water Cherenkov detector array and a composite array composed of 18 wide-angle Cherenkov telescopes. At the same time, the Tianfu Cosmic Ray Research Center has been built in Chengdu to fully support the scientific operation of the facilities.
According to reports, gamma burst is a sudden intensification of gamma rays from a certain direction in the sky, is the most violent celestial explosion phenomenon after the Big Bang, was first discovered in 1967, since 2019 humans have found 3 cases of gamma burst radiation photons with the highest energy of 1 TeV (1 TeV = 1 trillion electron volts). Completed in July 2021 and started high-quality and stable operation, "Lasso" is the most sensitive ultra-high energy gamma-ray detection device in the world, with a large field of view and all-weather characteristics, can monitor 2/3 of the sky area every day, this discovery fully reflects the world's leading sensitivity and unique advantages of "Lasso".
On October 9, 2022, Lasso recorded gamma photons from gamma burst GRB 221009A with a high temperature of more than 10 TeV, marking a milestone in the nearly 60-year history of gamma burst research. GRB 221009A, the brightest gamma burst in history, was produced by the collapse and explosion of a massive star more than 20 times heavier than the Sun when it ran out of fuel, after Lasso carefully measured the complete behavior of its TeV radiation over time, determined that its radiation originated from afterglow radiation, and revealed the brightest cause of the gamma burst in history, which was published in Science in June 2023.
Since then, Lasso has officially released the precise energy spectrum of high-energy gamma radiation of gamma burst GRB 221009A, with a maximum energy of more than 10 trillion electron volts, which challenges the traditional standard radiation model of gamma burst afterglow, revealing that the absorption of high-energy gamma light by cosmic background light is lower than expected, and the intensity of cosmic background light in the infrared band is only about 40% of what the existing cosmological model expects. This result will prompt a reconsideration of the formation and evolution of galaxies in the universe. At the same time, the energy spectrum provides important information for new physics research such as testing the application range of Einstein's theory of relativity and exploring the candidate particle of dark matter, the axon. The results were published in Science Advances on November 15, 2023.
Chengdu Daily Jinguan News Reporter Huang Xuesong Yang Fan According to the interviewee Xinhua News Agency Editor-in-charge Chang Lijuan Editor Wang Yiran