Rapid radio burst（Fast Radio Bursts， FRB）, is a mysteriousGalaxyExternal radio astronomical phenomena.The duration of the eruption is only a few milliseconds, but it can show extremely high brightness in this very short time, which is equivalent to the energy released by the sun in a whole day.[1]
The polarization properties of fast radio bursts contain abundant information about their intrinsic characteristics and formation environment. Accurate measurement of the polarization properties of fast radio bursts will continue to promote the understanding of the environment and origin of fast radio bursts.[9]
distantuniverseThe sudden appearance of a short and bright burst of radio waves in, which was first reported nearly a decade ago, has always puzzled astronomers.Only a few of these mysterious events have been confirmed conclusively, but previous observations have not revealed many details about how and even where they happened.
Analyzed nearly 700 hours of American countriesscienceAfter the NSF Green Causeway Telescope (GBT) archived the data, a group of astronomers have discovered a fast radio storm event with the most details so far.These newly analyzed data, including both linear polarization and circular polarization data, indicate that the explosion occurred in a highly magnetized region, which may be a recent supernova or an active star forming nebula.
Rapid radio bursts are usedradio telescopeAlthough the detected flash lasts less than a second, it contains more energy than our sun has emitted for hundreds of thousands of years.So far, only 11 FRB events have been confirmed conclusively, but astronomers believe that thousands of such eruptions occur every day in the observable universe.However, to find them, we need to carefully and carefully analyze the current and archived daily radioAstronomyObservation record data.
In the fast radio bursts previously observed, only the data of over circular polarization were detected.Part of the reason for this is the observation ability of the telescope, as well as the limitation of the telescope data that can be stored.The Green Causeway Telescope not only has the ability to detect complete polarization images, but also has sufficient observation data for archiving.
By studying the linear polarization data detected recently, the researchers found that the radio waves emitted from the rapid radio storm showed Faraday rotation effect, which was a spiral twist when the radio waves passed through a strong magnetic field, and its shape was like a screwdriver to open the cork of a grape wine bottle.
Further analysis of the signal shows that it passed through two different ionized gas regions called (scattering) screens on its way to the earth.By analyzing the interaction between the two screens, astronomers can determine their relative positions.The strongest screen is very close to the source of the explosion, within 100000 light years of the source, which places it in the galaxy where the source is located.Only two things can leave such a mark on the signal: the nebula around the source, or the ionized gas in the center of its galaxy.
In addition, researchers also found that the radio radiation of fast radio bursts has a phenomenon similar to the twinkling of stars.This kind of scintillation phenomenon in radio band usually occurs in the observation of pulsars.National Astronomical Observatory, Chinese Academy of SciencesDr. Li Yichao of the National Academy of Sciences analyzed the scintillation data of a pulsar in the direction of a fast radio burst, indicating that the scintillation part of a fast radio burst is caused by the interstellar medium of the Milky Way, just like a pulsar;At the same time, it also indicates that the outbreak location should be within 3 billion light years.
The 100m Green Bank Telescope is the largest telescope in the worldMovable radio telescope。Its location in the National Radio Tranquility Zone (USA) and the West Virginia Radio Astronomical Area enables this telescope with incredible sensitivity to conduct unique observations without unnecessary radio interference.National Radio ObservatoryIt is a facility of the National Science Foundation of the United States, operated by Union University Corporation under a cooperation agreement.[2]
Research progress
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In 2007, the Lorimer team found the first observed FRB event in human history: FRB 010724 from the historical archive data of Parkes telescope in Australia.[1]
On January 2, 2015, the National Astronomical Observatory of the Chinese Academy of Sciences released three new astronomical observation results, which are in turn the "census" of stars in the Milky Way, rapid radio bursts and black hole data.The "fast radio storm" was discovered by researchers from the National Astronomical Observatory of China in an international cooperation project, which may be a recentSupernova remnantOr active star nebulae.[3]
In July 2020, the journal Nature published a report on periodic repeated rapid radio bursts, whose periodic characteristics of about 16 days will be a huge step forward for us to reveal the origin of rapid radio bursts.[1]
In February 2021, the team of Dr. Niu Chenhui from the research team of Li Di and Zhu Weiwei of the National Astronomical Observatory of ChinaFASTThree new cases of high dispersion fast radio bursts found in massive data[7]。
In March 2022, the Chinese scientific research team observed and calculated the origin evidence of rapid radio bursts through the "China Tianyan" FAST. This discovery was published in the international authoritative academic journal Science on March 18.Li Di, a researcher at the National Astronomical Observatory of the Chinese Academy of Sciences and the chief scientist of "China's Celestial Eye", said that a fast radio burst is an extremely powerful electromagnetic wave burst in the radio band, which is an extreme explosion in the universe."The energy released by fast radio bursts in a few milliseconds is equivalent to the energy released by the sun in a few days or even a year. Studying the mechanism of such extreme explosions may have a revolutionary impact on physics and astronomy," Li Di said.[8-9]
2022On September 21, the FAST priority and major scientific research team participated by Professor Li Kejia, Professor Dong Subo, Dr. Xu Heng, Dr. Chen Ping and others from Peking UniversityNatureAn article was published to evaluate the origin of the repetitive rapid radio burst FRB20201124A.The team observed the depth of the sourceSeveral important discoveries have been madesecond[13]。
In April 2024, it was learned from the National Astronomical Observatory of the Chinese Academy of Sciences that researcher Li Di of the National Astronomical Observatory of the Chinese Academy of Sciences led the team to propose a new analytical framework, "Pincus Lyaponov phase diagram", which can quantify the randomness and chaos of explosive events and reveal the essential difference between the time energy performance of rapid radio bursts and earthquakes, solar flares, etc,This difference challenges the starquake origin of rapid radio bursts.Through the strong observation ability of China Tianyan FAST and innovative analysis methods, scientists in the future may be able to deeply depict the mysterious explosion signals between the universe, which is expected to eventually reveal the origin of the universe.This research work was published as a cover article on the comprehensive journal Science Bulletin of the "Outstanding Action Plan for Chinese Science and Technology Journals" on April 12, 2024 Beijing time.[14]
Theoretical application
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Limitation Results of Three FRB Observations on the Difference of Post Newtonian Parameter γ
At the 100th anniversary of Einstein's general theory of relativity, the physics journal Physical Review Letters（Physical Review Letters）On December 23, 2015, in the form of "Editors' Suggestion" (recommended by the editor in chief), Wu Xuefeng, chief researcher and Wei Junjie, assistant researcher of the High Energy Time Domain Astronomy Group of Zijinshan Observatory, Chinese Academy of Sciences, Gao He, associate professor of Beijing Normal University, and Peter M é sz á ros, professor of Pennsylvania State University in the United States (Einstein chair professor of the Chinese Academy of Sciences in 2013) were publishedThe latest test results on Einstein's equivalent principle (Wei, Gao, Wu&M é sz á ros, 2015,Phys.Rev.Lett., 115, 261101）。This study uses the time difference of photons with different frequencies from fast radio bursts to reach the Earth, and accurately verifies the weak equivalence principle hypothesis in Einstein's general theory of relativity.
Although the physical origin of fast radio bursts is not clear at present, most of them erupt at high silver latitudes, and their dispersion amount is far more than the contribution of galactic interstellar media, so they are generally considered as extragalactic or even cosmological origin.On the other hand, the light variation curve of fast radio bursts generally presents simple single pulse characteristics, and it is easy to obtain the observation time delay of photons with different radio frequencies.Wu Xuefeng and others proposed that the fast radio bursts of extragalactic or cosmological origin can be used to accurately test Einstein's equivalence principle.In this work, a fast radio burst FRB 110220 and two possible co events of fast radio bursts and gamma bursts (FRB/GRB 101011A and FRB/GRB 100704A) are used as examples. It is calculated that when radio photons with different frequencies are used as test particles, the upper limit of the difference between the post Newtonian parameter γ is limited to 10 orders of magnitude.This result is the best limit result so far, which is at least 1-2 orders of magnitude higher than the previous related limit, and extends the test of Einstein's equivalent principle to the radio band, thus further proving the correctness of the hypothesis of Einstein's equivalent principle.[4]
Observation progress
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Progress in the Study of Pulsars and Rapid Radio Bursts
In astronomical research, it is usually difficult to measure the distance between the celestial body and the earth, but the distance is the most basic parameter.Pulsar distance is the most basic parameter for further research on the origin, evolution, distribution and radiation characteristics of pulsars.Only about one tenth of the more than 2000 pulsars that have been found so far have a measurement distance (independent of the distance of the model).In recent years, fast radio bursts are a kind of radio pulses with unknown origin, large dispersion and millisecond duration found in astronomical observations.The distance of fast radio bursts is very important for analyzing their origin and the location relationship with the Milky Way (Hanoi source or extragalactic source).Only two of the 17 fast radio storms detected have redshift measurements.
Shortly after the discovery of pulsars, scientists found that using pulsars to measure distance and dispersion (DM) can build an electron density model of the Milky Way.The model can be used to estimate the distance of all pulsars in the Milky Way with dispersion measurement, and the accuracy of the model distance greatly depends on the number and accuracy of pulsars measured at the known distance.The most recent electron density model of the Milky Way is the NE2001 model, which mainly describes theFree electron densityDistribution of.
the near future,Xinjiang Observatory, Chinese Academy of SciencesYao Jumei, a doctoral student, constructed a new electron density model (YMW16 for short).Compared with the existing models, YMW16 has the following advantages through observation in the past decade: 1. The number of pulsars with measurement distance has doubled, and the accuracy of structural parameters of the Milky Way has improved;IIMagellan CloudThe number of pulsars increases, and the understanding of Magellanic cloud structure is improved;3、 The rapid radio burst was found, and theIntergalactic mediumThe distribution of free electron density.Researchers seized the opportunity to propose YMW16, which not only improved the distance accuracy of the Milky Way pulsar model, which was nearly 40% better than NE2001 within the 95% confidence interval, but also was the first model that can be used to estimate the distance of Magellanic cloud pulsars and rapid radio bursts.Yao Jumei teaches RN. Manchester completed this work under the guidance of his tutor Wang Na.Relevant research results have been published in The Astrophysical Journal (2017, 835, 29).
In the future, the increase of the number of pulsars with measuring distance, more accurate Galaxy structure and more rapid radio burst redshift measurements will help people to further detect and improve the accuracy of range estimation of YMW16.[5]
Astronomers have observed the brightest "fast radio storm" so far
Astronomers have observed the brightest "fast radio storm" so far
California Institute of TechnologyAstronomyThe scientist Vikram Ravi and his colleagues have detected the brightest fast radio burst (FRB) so far.A fast radio burst is a strong radio beam that lasts only a few milliseconds. Its mysterious origin is still a mystery.
So far, only 18 rapid radio bursts have been detected by astronomers, most of which are only single bursts and will not explode repeatedly.In addition, the resolution of most fast radio bursts detected by astronomical telescopes is poor, which makes it difficult to accurately locate the location of the bursts.At present, the newly observed bright and fast radio storm FRB 150807 can enable astronomers to locate the location of the eruption more accurately.[6]
In 2022, China's Tianyan FAST found the first continuously active rapid radio storm, and this achievement was published in the international academic journal Nature on June 9, 2022 Beijing time.[10]。On June 9, a research achievement on rapid radio bursts from China's "Tianyan" (FAST) was published in the international academic journal Nature.[11]
In 2022, the scientific research team of China Tianyan FAST Fast Radio Burst Priority and Major Project carried out deep observation of the fast radio burst 20201124A, obtained the largest polarization observation sample of fast radio bursts so far, and detected for the first time the magnetic field changes in the surrounding environment only 1 astronomical unit (i.e. the distance from the sun to the earth) from the center of fast radio bursts,It is a key step to determine the engine mechanism of the rapid radio burst center.This achievement was published in the international academic journal Nature on September 21, 2022 Beijing time.[12]
