Beijing, March 3 (Zhongxin Net) -- As the most violent explosion phenomenon since the Big Bang, gamma-ray bursts (gamma-ray bursts) have long been an important field for astrophysicists to continue to track observations and focus research.
The Chinese Academy of Sciences held a press conference in Beijing on the Huiyan satellite and the polar eye space telescope to accurately detect the brightest gamma-ray bursts to date. Photo by Sun Zifa, reporter of China News Agency
The largest brightness gamma-ray burst to date was discovered
The Institute of High Energy Physics of the Chinese Academy of Sciences (Institute of High Energy of the Chinese Academy of Sciences) and more than 40 scientific research institutions around the world jointly released in the early morning of the 29th Beijing time, based on the high-precision measurement of gamma-ray bursts produced by China's "Insight-HXMT" and "Polar Eye" space telescope (GECAM-C) in the depths of the universe 24.221009 billion light-years from the earth, and found that it has the maximum brightness observed so far, increasing the brightness record of gamma-ray bursts by 50 times.
The Chinese Academy of Sciences held a press conference in Beijing on the Huiyan satellite and the polar eye space telescope to accurately detect the brightest gamma-ray bursts to date. Photo by Sun Zifa, reporter of China News Agency
Through the "Insight" and "Polar Eye" in the hard X-ray and soft gamma energy bands of the instantaneous radiation and early afterglow of GRB 221009A gamma-ray burst successfully carried out the highest international precision measurement so far, not only to achieve accurate detection of the brightest gamma burst to date, but also found that its isotropic energy also broke records, equivalent to releasing all the energy of 1 solar masses in 8 minute, but also revealed that the gamma burst produced an extremely narrow, extremely bright, near-light-speed motion jet.
This important research work was completed by an international cooperation team from more than 30 research institutions in China, the United States, Italy, France, Germany and other research institutions led by the Key Laboratory of Particle Astrophysics of the Chinese Academy of Sciences, and the relevant results and papers have been published online on the preprint platform. Professor Xiong Shaolin, Deputy Director of the Center for Particle Astrophysics of the Institute of High Energy of the Chinese Academy of Sciences and Chief Scientist of the "Polar Eye" Space Telescope, Professor Zhang Shuangnan, Director of the Center for Particle Astrophysics of the Institute of High Energy of the Chinese Academy of Sciences and Chief Scientist of the "Huiyan" satellite, Professor Zhang Bing of the University of Nevada, Las Vegas, are the co-corresponding authors of the paper, and another 175 international cooperation teams are the signed authors of the paper.
Imaging image of the brightest gamma-ray burst (GRB 221009A) ever discovered. Photo courtesy of Institute of High Energy of the Chinese Academy of Sciences
A once-in-a-millennium celestial explosion event
The research team said that gamma-ray bursts include two types, one is a collapse explosion in the core of a very massive star, which usually lasts longer than 2 seconds, and the brightest gamma-ray burst discovered so far belongs to this category; The other is a combined explosion of two extremely compact objects (neutron stars, black holes, etc.), usually lasting less than 2 seconds, and emitting gravitational waves at the same time.
Both types of objects explode to produce an extremely compact object such as a black hole or a neutron star, which devours surrounding material through extreme gravity and ejects material from the poles at close to the speed of light, forming a pair of jets in opposite directions. Processes such as shock waves or magnetic reconnection inside the jet accelerate the production of gamma-ray radiation by charged particles, called instantaneous radiation. Jets interacting with the surrounding interstellar medium can also produce radiation, called afterglow. Only when the jets are right on Earth will humans have a chance to detect this radiation.
Since the first gamma-ray bursts were discovered in 1967, scientists have detected nearly 2022,10 gamma-ray bursts. On October 9, 221009, GRB 24A gamma-ray bursts were observed by many astronomical facilities around the world, including the space and ground observation equipment led by the Institute of High Energy of the Chinese Academy of Sciences, which has extreme brightness and relatively close distance (<>.<> billion light-years from Earth), making it a veritable once-in-a-millennium historic celestial eruption.
Researcher Zhang Shuangnan explained that although there are definitely brighter gamma-ray bursts in the universe, because their jets are pointing exactly at the Earth and the chance of being detected is very rare, the study accurately detected the brightest gamma-ray bursts so far "is a once-in-a-millennium or even once-in-a-decade event."
Schematic view of the brightest gamma-ray burst seen by the Eye satellite and the Polar Eye space telescope. Photo courtesy of Institute of High Energy of the Chinese Academy of Sciences
Why can "Insight" and "Polar Eye" detect accurately
Since GRB 221009A gammabursts have been observed by many astronomical facilities around the world, why can China's "Discerning" and "Polar Eye" carry out the highest international precision measurement and accurate detection so far?
Researcher Xiong Shaolin pointed out that the "Polar Eye" space telescope built by China specifically for the detection of gamma-ray bursts and gravitational wave electromagnetic counterparts, and the "Huiyan" satellite, China's first space X-ray astronomical telescope, have accurately depicted the radiation properties of GRB 221009A gamma-ray bursts at each key stage from precursor radiation to main burst, flare, and early afterglow in the hard X-ray and soft gamma-ray energy segments.
Among them, the "polar eye" is precisely in the special observation mode that can record the extremely high gamma ray flow intensity, avoiding various instrument effects (including data saturation loss, signal accumulation, excessive dead time, etc.) that are easy to occur due to extreme brightness, and successfully carried out a complete and accurate detection of the extremely bright main burst of the gamma-ray burst. At the same time, the high-energy X-ray telescope equipped by Huiyan successfully detected the gamma-ray burst with its maximum effective area in the megaelectron voltaic energy region, and obtained high-quality data of its precursor radiation and early afterglow.
Based on the accurate observation data of the "polar eye", the research team found that GRB 221009A gamma-ray burst has the highest brightness detected so far, and increased the gamma-ray burst brightness record by 50 times, and found that the isotropic energy of the gamma-ray burst also broke the record, equivalent to releasing all the energy of 1 solar masses in 8 minute.
At the same time, the research team speculated based on the joint observation results of "Insight" and "Polar Eye" that the afterglow of GRB 221009A gamma-ray burst from slow decay to fast decay appeared very early, which means that the jet producing gamma rays is very narrow, which is one of the narrowest gamma-ray burst jets detected by humans. The team believes that the extremely narrow jets may be one of the reasons why the gamma-ray burst appears extremely bright. Therefore, the observation and research results of the brightest gamma-ray burst so far also provide a new perspective for the academic community to deeply understand similar extreme cosmic explosions.
At the press conference, Professor Andrea Santangelo of the University of Tübingen, Germany, commented on the results. Photo by Sun Zifa, reporter of China News Agency
The joint observation of space and earth made a number of first-time discoveries
According to the Institute of High Energy of the Chinese Academy of Sciences, the scientific engineering of the "Huiyan" satellite and the "Polar Eye" space telescope were proposed and led by the institute. Among them, since the successful launch of "Huiyan" in June 2017, the satellite has been operating stably in orbit for more than five years, and has achieved a series of important results in the fields of black holes, neutron stars, and fast radio bursts. The "Polar Eye" (also known as "Huairou-6") satellite is an opportunistic space science project specially supported by the strategic leading science and technology of space science (phase II) of the Chinese Academy of Sciences.
Participating in the discovery and study of the brightest gamma-ray burst to date is the third space payload in the Polar Eye series, the Polar Eye space telescope, which was launched into orbit in July 2022 aboard the China Space New Technology Test Satellite (SATech-7). "Polar Eye" adopts a series of innovative detection technologies and pioneers the use of Beidou navigation system short message service to achieve satellite-ground quasi-real-time communication, and has discovered a large number of high-energy bursts such as gamma-ray bursts, magnetar bursts, high-energy counterparts of fast radio bursts, solar flares and Earth's gamma flashes.
The Institute of High Energy of the Chinese Academy of Sciences revealed that in the historical observation of GRB 221009A gamma burst once in a thousand years, the institute's ground-based large scientific device - high-altitude cosmic ray observatory (English abbreviation LHAASO, Chinese nicknamed "Lasso") and two space facilities "Huiyan" and "Polar Eye" also carried out space-ground joint observations, of which "Lasso" used its large number of very high-energy observation data to also obtain a number of important first discoveries, which will be announced after the publication of the results paper. (End)