China's Five-hundred-meter Aperture Spherical Radio Telescope (FAST), the world's largest and most sensitive filled aperture radio telescope, has identified more than 1,000 new pulsars, its operator said on Tuesday.
Pulsars, or fast-spinning neutron stars, originate from the imploded cores of massive stars that are dying following supernova explosions.
The number of new pulsars discovered by FAST has surpassed that of all foreign telescopes combined during the same period, according to the National Astronomical Observatories at the Chinese Academy of Sciences (NAOC).
Since FAST found the first pulsar in October 2017, Chinese research teams have discovered more than 750 pulsars, including sporadic pulsars, millisecond pulsars, pulsar binary systems, through pulsar snapshot survey of the Milky Way disk.
More than 200 pulsars have also been discovered through other observation methods such as Commensal Radio Astronomy FAST Survey (CRAFTS).
"The Milky Way's disk is where stars gather. A large number of stars evolve here and finally form pulsars. Among the pulsars discovered by our team, some of them feature pretty peculiar radiation patterns. They only occasionally emit some pulses, one in every few minutes. So these pulsars are very important, and humans didn't know about them in the past. Pulsar radiation has been a mystery for half a century, and the FAST's highly-sensitive observing capabilities have provided new clues to the challenges," said Han Jinlin, a researcher at the NAOC.
Since it went in to service, FAST has also helped Chinese scientists achieve a number of important original results regarding fast radio bursts, neutral hydrogen, and nanohertz gravitational waves. Amongst these achievements, the discovery of a binary pulsar with the shortest known period and the capture of preliminary evidence of nanohertz gravitational wave signals have strengthened China's voice in the field of global radio astronomy research.
"Finding pulsars in batches provides us with an opportunity to make major scientific discoveries. We have now reached the forefront in just a few years, which is of great significance for testing some cutting-edge physical laws, such as Einstein's theory of general relativity. It can be said that China has made its own contribution to mankind's understanding of the mysteries of the universe," said Jiang Peng, the deputy director of the NAOC and the director of the FAST operation and development center.
Since 1967, when humans first discovered a pulsar, the search for them has never stopped.
Researchers said that pulsars, which record a lot of information about stars, are also called "astrophysical laboratories", as they reveal the mysteries of the universe. The discoveries of strange pulsars could even subvert human understanding of classical physics.
Experts said that when a medium-mass star evolves to the late stage, or when it runs out of the fuel it's burning, it will collapse into an extremely dense celestial body, which is a pulsar.
"For example, this is a pulsar model. Once the pulsar collapses, its mass is still greater than that of the sun, but its radius is only about 10 kilometers. It has a huge density. Its density and pressure are so high that the density of its core exceeds that of nuclear matter. It can be said that the atomic nucleus has been crushed. Therefore, in such an extreme celestial body, by studying it, we can understand the basics of particle physics at extremely high density. It is an extremely unique astrophysical 'laboratory' in the universe," said Zhu Weiwei, a researcher at the NAOC and the chief scientist at the FAST operation and development center.
As pulsars have many distinctive features, researchers hope to discover some strange pulsars, such as pulsar-black hole binary systems, or pulsars with particularly fast rotation periods, or even pulsars that subvert mankind's understanding of physics.
Through studies of these pulsars, scientists can better understand their physical properties, as part of the effort to use them to serve mankind.
"We can study various gravitational effects and particle physics. We can also use them to make precise measurements. Some pulsars rotate very fast. The fastest pulsar can rotate more than 700 times a second. It is a very accurate 'clock' in the universe. By measuring them, we can get a more accurate time measurement, which can be used for navigation. It could be useful in our daily life in the future," said Zhu.
China's FAST telescope identifies over 1,000 pulsars
