2020-11-13

“Sky Eye” asks the sky with unlimited potential

By yqqlm yqqlm

The discovery of more than 240 pulsars strongly supports high-level research

The”eyes of the sky” has unlimited potential to ask the sky

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Under the sun (above) and in the afterglow of the setting sun (below)”Chinese Sky Eye” (photographed during maintenance). Xinhua News Agency reporter Ou Dongqu photo

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Panoramic view of”China Sky Eye”. Published by Xinhua News Agency

On January 11 this year, China’s 500-meter-caliber spherical radio telescope (FAST), known as the “China Sky Eye”, passed the acceptance test, and it has the conditions for open operation. Today, the”China Sky Eye” has officially operated for more than 300 days.

While operating stably and reliably, FAST is”diligently” engaged in observation services. National Astronomical Observatory recently stated that FAST has discovered more than 240 pulsars. With the help of”Sky Eye”, the Chinese scientific research team quickly became the core research force in the field of international rapid radio storms.

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Chinese scientists have achieved a series of major achievements

Become the core force in the field of radio bursts

In the vast universe, often There are short and violent radio wave bursts, usually only a few milliseconds in duration, but they can release huge energy equivalent to tens of billions of years of power generation on the earth. In 2007, astronomers discovered such a millisecond radio wave, a fast radio burst, for the first time, and conducted exploration and research on it.

Who sent such a radio wave? What information does the fast flashing radio wave contain? For the past ten years, astronomers from various countries have been collecting and analyzing information. In 2017, astronomers captured a millisecond burst of radio waves, which was repeated multiple times within a few hours. Using the world’s many large radio telescopes to jointly detect and locate, finally locate a repetitive radio flash source in a galaxy 3 billion light years away in the depths of the universe.

“In the past, Chinese astronomers could not obtain first-hand materials because they did not have their own large radio telescopes. In this field, most of them can only engage in theoretical research.” Academician of the Chinese Academy of Sciences, National Astronomical Observatory Director Chang Jin said.

As the”China Sky Eye” was completed, debugged, and then officially put into operation and opened to domestic astronomers, Chinese forces in the field of rapid radio bursts rose rapidly.

The”China Sky Eye” has a huge light-gathering area and superb radio wave collection ability. It is the most sensitive radio telescope in the world. It has a precisely controlled deformation ability and can focus and stably track celestial bodies. With the help of FAST’s latest observations, Chinese scientists have achieved a series of important results.

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Astronomical tools help observation

Ending the theoretical battle of radio bursts

For the mysterious millisecond radio bursts, the previous theoretical research mainly There are two views-one is that millisecond radio bursts are caused by particle collisions, and the other is that they are caused by particles traveling through a strong magnetic field.

Han Jinlin, the chief researcher of the National Astronomical Observatory, said that the FAST observations directly ended the theoretical battle.”By analyzing the high-sensitivity polarization signals of 11 radio bursts, Chinese researchers used direct observations to deny the theory of particle collision.”

This research with a final word comes from a professor at Peking University and the country. Observatory researcher Li Kejia team. In 2019, the team used FAST to detect a repeated outbreak of FRB180301 with only 21 cases in the world.

The bigger surprise comes from the high-sensitivity polarization signal analysis of 11 bursts. Li Kejia said that in the past, telescopes in the world only recorded polarization signals for a few of more than 30 burst sources, and there are very few samples that can be studied in detail. The polarization measurement capability of the receiver equipped with FAST is very good. Among the 11 burst signals observed, 7 milliseconds of the bursts can be well resolved for their polarization.

According to Li Kejia, these seven polarizations are not only changing, but also showing a variety of changes. This shows that the source of explosions in the universe may come from physical processes in the magnetosphere of compact stars rather than particle collisions.

In August of this year, a joint research team including Dr. Lin Lin from Beijing Normal University, Dr. Chunfeng Zhang from Peking University, and Dr. Pei Wang from the National Astronomical Observatory used FAST to observe a known magnetar SRG1935+2154 in the Milky Way. Dozens of gamma-ray bursts. Wang Pei said that the FAST measurement results will play an important role in the study of the origin and physical mechanism of fast radio bursts.

On October 29 and November 4, the above two research papers were published in the journal Nature. In the research of this frontier field, Chinese scientists have been at the forefront.

“With great power tools, our position in the field of international astronomy is different. In the field of radio astronomy, we have entered the first team.” Academician of the Chinese Academy of Sciences, Director of the FAST Science Committee Wu Xiangping said.

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Looking for the first radio pulsar outside the Milky Way

The measurement technology has a broad application prospect

Formally”served” for nearly one year, FAST can be called a”model worker”. According to data released by the National Astronomical Observatory, FAST’s observation service exceeded 5200 aircraft hours, nearly twice the expected target, and the cumulative number of pulsars discovered exceeded 240, and more than 40 high-level papers based on FAST data were published.

Currently, the pulsars discovered by FAST include a new pulsar binary system called”Black Widow” and a millisecond pulsar with eclipse phenomenon known as the”Redback Spider”. With the high sensitivity of FAST, detailed changes such as pulsar signal eclipse phenomenon and pulsar signal arrival time delay are clearly observed.

Wu Xiangping said that it is expected that in the next five years, FAST will find 1,000 pulsars and even find the first radio pulsar outside the Milky Way.

With the improvement of performance, the scientific potential of FAST gradually appears. Its sensitivity is more than 2.5 times that of the world’s second largest single-aperture radio telescope. Its super sensitivity makes it a great potential for radio transient sources, and it is expected to realize nanohertz gravitational wave detection in a short time. At the same time, it also has the ability to extend my country’s deep space exploration and communication capabilities to the edge of the solar system to meet major national strategic needs.

FAST’s advanced measurement technology goes far beyond the telescope itself, and has important application prospects in other fields. Jiang Peng, a researcher at the National Astronomical Observatory and chief engineer of FAST, introduced that in high-precision geological and mineral exploration, FAST can use inertial components and satellite navigation fusion technology to provide high-precision position and azimuth attitude reference for gravity measurement; in marine surveying and mapping, inertial The components are integrated with sonar and other measurement technologies to realize submarine surveying and mapping, and establish high-precision time-space and attitude benchmarks for machinery and equipment operating in the exploration area.

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Competition for observation applications is fierce.

It will be open to the world next year

Only those who touch the telescope every day for observation can discover Frontier issues. Only by having its own”big telescope” can we make more original and world-leading results from an observation perspective.

In 1993, astronomers from 10 countries including China proposed to build a new generation of radio telescopes. Nanrendong, who is active in the international astronomy community, resolutely returned to China, urging China to build its own”big telescope” independently.

Since then, the site selection and pre-study began in 1994, and it was officially opened in September 2016, and then officially opened for operation at the beginning of this year. It took 26 years for the”China Sky Eye” to complete the pre-research. Nearly 100 scientific researchers went on to invest in the project, and finally realized the dream of the world’s leading”Sky Eye” from scratch.

In terms of engineering construction, FAST has achieved a number of independent innovations, which has significantly promoted the technological innovation and development of related industries in my country. FAST’s new design concept created a new model for building giant telescopes. Over the years, the engineering team has carried out a series of technical research, overcoming many technical problems in mechanics, measurement, control, materials, large-scale structures, etc., and all technical indicators have met the design requirements.

The reflective surface of FAST is equivalent to 30 football fields. It is the most sensitive radio telescope in the world. It greatly expands the field of vision of mankind and finally gives Chinese astronomers the opportunity to step onto the forefront of scientific research in the world.

In February of this year, when the new crown pneumonia epidemic was severe, the FAST team overcame difficulties and officially launched 5 priority and major projects selected by the scientific committee. Nearly 100 scientists began to use and process FAST scientific data. In April, the Time Allocation Committee began to solicit free application projects from the domestic astronomy community. So far, it has received more than 170 applications, of which the proportion of external users is as high as 95.7%.

FAST observations are highly competitive and hard to find. According to Chang Jin, director of the National Astronomical Observatory and academician of the Chinese Academy of Sciences, the telescope has received about 5,500 hours of applications, but only 1,500 hours have actually been approved, that is, less than 30%of the application time can be supported.

Despite the”supply of observations”, FAST will continue to be open to scientists around the world, making the”China Sky Eye” the”eye of the world” in the field of astronomy.

“In the next 10 years, China will usher in the golden age of radio astronomy development.” Wu Xiangping said that in order to exert greater scientific value, we plan to open FAST to scientists all over the world next year and work together to explore The mystery of the universe, contribute to the advancement of human civilization, and build a community with a shared future for mankind.

Source:People’s Daily Online