China's FAST in the Hunt for Nanohertz Gravitational Waves

China's FAST in the Hunt for Nanohertz Gravitational Waves
by Simon Mansfield
Gerroa, Australia (SPX) Jul 03, 2023

A recent breakthrough in the field of gravitational wave detection has been achieved by scientists in China, who have found vital evidence of nanohertz gravitational waves, thanks to pulsar timing observations performed with the Five-hundred-meter Aperture Spherical radio Telescope (FAST).

The study was spearheaded by the Chinese Pulsar Timing Array (CPTA), a collaborative group of researchers from the National Astronomical Observatories of the Chinese Academy of Sciences and various other institutions. The results of their findings were made public in the Chinese journal Research in Astronomy and Astrophysics.

Gravitational waves are effectively distortions or "ripples" in the fabric of space-time, brought about by the movements of massive bodies such as black holes. Despite their weak signals, these waves are an invaluable tool in detecting the elusive dark matter in the universe.

The detection of gravitational waves of nanohertz frequencies promises profound implications for our understanding of the universe's structure. It could unveil the development, evolution, and merging of the universe's most colossal bodies - supermassive black holes.

Nevertheless, the challenge lies in the detection of nanohertz gravitational waves due to their extraordinarily low frequencies. Their periods can span several years, and their wavelengths can reach up to several light-years. Large radio telescopes conducting long-term observations are currently the only known method for their detection.

Li Kejia, the article's corresponding author and a researcher at the National Astronomical Observatories, stated that the team currently lacks the ability to identify the astronomical sources of the detected signals due to the relatively short observational period of the current data. However, as subsequent observations extend, this issue will be resolved.

The pursuit of nanohertz gravitational waves has captured the attention of physicists and astronomers worldwide. Research teams in the United States, Europe, and Australia have been gathering pulsar timing data for over 20 years. In contrast, Chinese scientists initiated this line of work using FAST in 2019.

The CPTA credits its rapid progress to FAST's superior sensitivity and robust capacity to monitor pulsars. It is noteworthy that their significant breakthroughs align with those achieved by other global research teams, such as the North American Nanohertz Observatory for Gravitational Waves, the European-Indian Pulsar Timing Array, and the Australian Parkes Pulsar Timing Array. These international teams also released comparable results this week.