Li Jing, a researcher at the National Astronomical Observatory of the Chinese Academy of Sciences, introduced the latest scientific research results of FAST at the press conference. Photo by Sun Zifa, a reporter from China News Service
Beijing, January 6 (Reporter Sun Zifa) Known as the "Eye of Heaven" of the Chinese Academy of Sciences, the 500-meter aperture spherical radio telescope (FAST) of the National Astronomical Observatory of the Chinese Academy of Sciences has been operating with high quality through national acceptance for nearly two years and open to the world for nearly a year, and has made a series of important scientific achievements in important astronomical fields such as neutral hydrogen spectral line measurement of interstellar magnetic field, rapid radio burst observation and research.
Wang Pei, associate researcher of the National Astronomical Observatory of the Chinese Academy of Sciences, introduced fast scientific research achievements in the field of fast radio storms at the press conference. Photo by Sun Zifa, a reporter from China News Service
In the early morning of January 6, Beijing time, the international cooperation team led by researchers from the National Astronomical Observatories of the Chinese Academy of Sciences adopted the original neutral hydrogen narrow line self-absorption (HINSA) method to make significant progress in measuring the interstellar magnetic field through the "Chinese Heavenly Eye", which was published online by the international academic journal Nature as a cover article.
On the eve of the publication of the paper, the Chinese Academy of Sciences held the first press conference of 2022 in Beijing on January 5, introducing the high-quality open operation of the big country heavy weapon "China Sky Eye" and a series of important scientific research progress.
Han Jinlin, a researcher at the National Astronomical Observatory of the Chinese Academy of Sciences, introduced fast's scientific research progress in pulsar search at the press conference. Photo by Sun Zifa, a reporter from China News Service
Provides important observational evidence for solving the problem of star formation
Magnetic fields play an important role in the production of stars, planets and life, but the process is complex, the "magnetic flux problem" is therefore one of the three classic problems in star formation, and the measurement of interstellar magnetic field strength of molecular clouds has become a common challenge for the global astronomical community.
The international cooperation team led by Li Jing and Qing Daochong of the National Astronomical Observatory of the Chinese Academy of Sciences adopted the original neutral hydrogen narrow line self-absorption method, and used the "Chinese Heavenly Eye" to obtain the high confidence Zeman effect measurement results in the protostar nuclear envelope for the first time, and found that the magnetic field structure of the interstellar medium from cold neutral gas to the prostar nucleus has a coherent magnetic field structure, which is different from the Standard Model prediction, thus providing important observational evidence for solving the "magnetic flux problem" of one of the three classical problems of star formation.
Researcher Li Jing said that neutral hydrogen is the most abundant element in the universe, which is widely present at different times in the universe and is one of the best tracers for the distribution of matter at different scales. In the latest research, the research team used the unparalleled sensitivity and excellent optical path design of the "Chinese Sky Eye" to realize the detection of the self-absorbing Zeeman effect of the narrow line of neutral hydrogen for the first time, and obtained a high-confidence interstellar magnetic field measurement, which is a breakthrough in the use of atomic radiation to detect the molecular cloud magnetic field "from 0 to 1".
He said the magnetic field detected by China's Sky Eye was only one-hundred-thousandth of earth's magnetic field, at least 3 to 4 times weaker than the magnetic field predicted by the Standard Model of Star Formation. The results of the study reveal that molecular clouds can reach a magnetic supercritical state ahead of schedule at the dense cloud core stage, and there may be a more efficient magnetic field dissipation mechanism than the Standard Model to cause star formation to occur ahead of schedule. Therefore, this achievement is expected to expand the neutral hydrogen narrow line self-absorption method into an important systematic probe for interstellar magnetic field measurement.
Nature cover design, showing the interstellar medium and magnetic field in the Molecular Cloud Region of Taurus. Courtesy of the National Astronomical Observatory
Obtain samples of the largest rapid radio burst event to date
Fast radio bursts (FRBs) are currently the brightest explosive phenomena in the radio band of the known universe, with unknown origins, and are one of the largest astronomical hotspot frontiers today. At present, hundreds of rapid radio bursts have been detected, and only a few of them have shown repeated outbreaks.
The international cooperation team led by Li Jing, Wang Pei and Zhu Weiwei of the National Astronomical Observatory of the Chinese Academy of Sciences used the "Chinese Heavenly Eye" to observe the fast radio burst number frb121102, which is also the first repeated burst known to mankind, detected 1652 outbreak events in about 50 days, obtained the largest sample of fast radio burst event so far, exceeding the total number of outbreak events published in all previous articles in the field of fast radio bursts, and for the first time revealed the complete energy spectrum of the rapid radio burst rate and its bimodal structure. The result paper was published in Nature in October 2021.
Associate researcher Wang Pei said that the "China Sky Eye" multi-scientific target sky survey has found at least 6 new rapid radio bursts, which is making a unique contribution to revealing the mechanism of mysterious phenomena in this universe and promoting this new research in astronomy. He said that the search for fast radio bursts by the "Chinese Tianyan" on the ground and the Chinese "Huiyan" satellites in space is complementary in the way of research.
In response to the "Wise Eye" satellite observation and research confirmation, the number of FRB200428 very bright fast radio burst from the Milky Way number SGR J1935 + 2154 magnetar this scientific research results, the Chinese Academy of Sciences National Astronomical Observatory Han Jinlin researcher believes that fast radio bursts in the Milky Way only account for a small part, most of them outside the Milky Way, "Wise Eye" satellite to confirm that the source of magnetar is only a fast radio burst in the Milky Way, its origin will be followed by more observations and in-depth research.
As for the question of how many fast radio bursts there are in the universe, Li Believes that it is impossible to count at present, but according to fast observation data, at least 120,000 fast radio bursts in the universe reach the earth every day.
Fast radio burst FRB 121102 energy distribution of average hourly burst rate (left). FAST Observation Fast Radio Burst Artistic Imagination (right) Courtesy of the National Astronomical Observatory
The "Silver Road Surface Pulsar Snapshot Survey" has discovered 279 new pulsars
The "China Sky Eye" major priority project "Silver Road Surface Pulsar Snapshot Survey" led by researcher Han Jinlin is mainly aimed at using the "China Sky Eye" to "take pictures" of the Milky Way galaxy and discover new pulsars.
He said that the discovery of pulsars is one of the main scientific targets for observation by large international radio telescopes. Since the "Silver Road Surface Pulsar Snapshot Survey" project officially launched the pulsar search observation in February 2020, as of now, in less than two years, about 620 machine hours have been observed, and 279 new pulsars have been discovered, of which 65 are millisecond pulsars with a period of less than 30 milliseconds, and 22 can be confirmed in the binary star system, surpassing the number of pulsar discoveries in the United States Arecibo Telescope for 15 years. International astronomical peers commented that FAST "found so many pulsars impressively" and "the discovery of so many millisecond pulsars is a remarkable achievement"
Han Jinlin said that the project team fully explored the advantages of the "Chinese Sky Eye" in three aspects, such as huge receiving area, accurate deformation tracking ability, and multi-beam reception, and the invented "snapshot" observation mode greatly increased the search depth of pulsars, making the depth of search of the pulsar system break through from the order of millialky to the order of micro-yangsky. He especially hopes to find more "rare pulsars" and achieve major breakthroughs in basic fields such as astronomy and physics through research.
At present, the project team has observed 8% of the planned sky area and collected about 6 petabytes of data in the area with a high probability of pulsar appearance. In May 2021, the relevant achievement papers have been published in the professional academic journal "Astronomy and Astrophysics Research".
PSR J0318+0253 position and integrated pulse profile (left); FAST-FermiLAT collaborates on pulsar observations. Courtesy of the National Astronomical Observatory
Multi-band cooperative observations open up new directions for pulsar searches
According to the National Astronomical Observatory of the Chinese Academy of Sciences, "China's Sky Eye" has also opened up new directions for pulsar searches and opened up new ways to study the electromagnetic radiation mechanism of pulsars through multi-band cooperative observations. Based on the international leading advantage of the sensitivity of "China Sky Eye", the combination of "China Sky Eye" and the Fermi Gamma Ray Observatory Large Field Telescope (Fermi-LAT), an important space astronomical facility in the high-energy band, to carry out space-earth integration coordination and follow-up observation, has the potential to produce major scientific breakthroughs.
In this regard, the international cooperation team led by Li Jing and Wang Pei has discovered multiple pulsars and carried out multi-band observation and analysis. The paper was published in the academic journal science journal of Science in China in December 2021 in the form of cover and editorial comments.
Li Believes that multi-band cooperative observations through the "Chinese Celestial Eye" will hopefully provide more samples for the evolution of sub-star families and the detection of gravitational waves.
At the press conference, the Chinese Academy of Sciences said that it will share scientific research facilities with the world with a more open attitude, provide a high-level observation platform for the international astronomical community, promote international cooperation in astronomical research, enhance the international status and influence of China's astronomical research, and promote the development of world science and technology and the progress of human civilization. (End)