China’s FAST discovers 240 pulsars

Photo shows the world’s largest filled-aperture radio-telescope, the Five-hundred-meter Aperture Spherical Telescope (FAST) in Qiannan Buyei and Miao autonomous prefecture, southwest China’s Guizhou province. (Photo by Deng Gang/People’s Daily Online)

Being put into service for 300 days, China’s Five-hundred-meter Aperture Spherical Telescope, also known as FAST, has showcased remarkable performance. It has observed and served more than 5,200 hours, discovering more than 240 pulsars. In addition, more than 40 high-level papers have been published based on the telescope’s data.

A series of major achievements in the study of fast radio bursts were reached recently based on the latest observation of the FAST. Two relevant papers were published on science journal Nature on Oct. 29 and Nov. 4, respectively, once again putting the gigantic Chinese telescope on the center of radio astronomy.

Fast radio bursts, a transient radio pulse caused by some high-energy astrophysical process, is able to release as much energy in a few milliseconds as the sun puts out in a day. Some previous studies believed that such bursts came from collisions of particles, while some held they were generated by particles passing through strong magnetic fields.

“The observation of the FAST has put an end to the debate between the two explanations,” said Han Jinlin, chief researcher at the National Astronomical Observatories of the Chinese Academy of Sciences. Through the analysis of polarization signals released by 11 fast radio bursts, Chinese researchers denied the particle collision theory with direct observation results, he explained.

In August this year, a research team joined by Beijing Normal University’s researcher Lin Lin, Peking University’s researcher Zhang Chunfeng, and National Astronomical Observatories’ researcher Wang Pei discovered dozens of gamma-ray bursts from a known magnetar SRG1935+2154 in the Milky Way Galaxy with the FAST.

“We didn’t discover a single fast radio burst in our observation, despite the high sensitivity of the FAST. It indicated that the bursts of compact objects in different radio frequency have harsh physical conditions, which makes it impossible for radio and gamma-ray photon to reach the Earth at the same time,” said Lin.

The FAST, completed in 2016, has a reflector as large as 30 standard soccer pitches. It tremendously expands human’s vision in radio frequencies, and also offers an opportunity for Chinese radio astronomic scientists to reach the frontier of scientific exploration.

“People detected pulsar for the first time in 1967. Fifty years later, the Chinese were finally able to discover a pulsar with their own telescope FAST,” said Wu Xiangping, director of the FAST Science Committee and Academician of the Chinese Academy of Sciences. According to him, the Chinese telescope is expected to discover a total of 1,000 pulsars in the next five years, and is even able to find the first radio pulsar outside the Milky Way Galaxy.

In February this year, the FAST team officially launched the five prioritized and major projects selected by the FAST Science Committee. Two months later, the Time Allocation committee started soliciting free applications from the Chinese astronomical community. So far, it has received over 170 applications.

Wu told People’s Daily that the FAST will be opened to the world the next year, believing the next decade will be a golden time for China’s radio astronomy development. “We will make good use of this valuable window phase to make major scientific findings, so as to make great contribution to human being’s exploration and understanding of the universe,” he said.