China's FAST telescope finds key evidence for nanohertz gravitational waves

This aerial photo taken on June 22, 2023 shows China's Five-hundred-meter Aperture Spherical Radio Telescope (FAST) under maintenance in southwest China's Guizhou Province. (Xinhua/Ou Dongqu)

GUIYANG, July 3 (Xinhua) -- China's FAST telescope found key evidence for the existence of nanohertz gravitational waves, which is important in studying problems in contemporary astrophysics such as supermassive black holes, the history of galaxy mergers, and the formation of large-scale structures in the universe.

The research, conducted by scientists from the National Astronomical Observatories of the Chinese Academy of Sciences (NAOC) and other institutes, was published in the journal Research in Astronomy and Astrophysics online on Thursday.

Nanohertz gravitational waves lend a hand in understanding the formation of the universe's structures and investigating the growth, evolution, and mergers of the most massive celestial objects in the universe, that is, supermassive black holes, according to scientists.

The scientists monitored 57-millisecond pulsars with regular cadence for 41 months and found key evidence for quadrupole correlation signatures compatible with the prediction of nanohertz gravitational waves at a 4.6-sigma statistical confidence level (with a false alarm probability of two in a million).

Li Kejia, a researcher of NAOC and professor at Peking University, said that the detection of nanohertz gravitational waves is very challenging due to their extremely low frequency, long periods, and light-years wavelengths. So far, long-term timing observation of millisecond pulsars with extreme rotational stability is the only known effective method for detecting nanohertz gravitational waves.

Located in a naturally deep and round karst depression in southwest China's Guizhou Province, FAST started formal operation in January 2020. It is believed to be the world's most sensitive radio telescope.