Using China’s FAST telescope, researchers have discovered six distant galaxies that are rich in hydrogen and have great potential for star formation, significantly expanding our understanding of the early universe.

Dr. Hongwei Xi of the National Astronomical Observatories of the Chinese Academy of Sciences (NAOC) and his team have discovered the properties of six newly identified high-redshift galaxies. This discovery was made using the Five-hundred-meter Aperture Spherical Radio Telescope (FAST) in Guizhou Province, China. Their results were published in The Astrophysical Journal Letters.

These remarkable galaxies, whose radio wave emissions took almost the age of the solar system to reach us, contain larger amounts of atomic hydrogen gas than the tens of thousands of galaxies previously studied in the local universe with other radio telescopes.

The researchers concluded that galaxies four billion years ago had much more gas for star formation than galaxies today, and that distant galaxies have much larger gas reserves than previously thought.

The importance of FAST and international cooperation

“These discoveries are part of the ongoing FAST Ultra Deep Survey and demonstrate the tremendous sensitivity of the world’s largest radio telescope,” said Prof. Bo Peng of NAOC, one of the corresponding authors. “The new FAST survey has so far discovered over 100 new galaxies at distances of up to five billion light years, and the final number is expected to be over 1000.”

Finding the optical counterparts to the new radio discoveries has become a detective story, as galaxies at such great distances are very faint. In addition, localization is difficult due to the difference in wavelength accuracy of FAST is not as good as that of optical telescopes.

Using the largest optical telescopes in the US and Russia, the team’s experts were finally able to identify these counterparts. It turned out that these counterparts contained two to three times more stars than the Milky Waybut contain about ten times the mass of hydrogen gas.

“This collaboration between Chinese and Australian radio astronomers demonstrates the enormous potential of the new generation of radio telescopes, which will include the international Square Kilometre Array Observatory (SKAO) later this decade,” said Prof. Lister Staveley-Smith of the University of Western Australia, node of the International Centre for Radio Astronomy Research, the other corresponding author.

Reference: “The Most Distant H i Galaxies Discovered by the 500 m Dish FAST” by Hongwei Xi, Bo Peng, Lister Staveley-Smith, Bi-Qing For, Bin Liu, Ru-Rong Chen, Lei Yu, Dejian Ding, Wei- Jian Guo, Hu Zou, Suijian Xue, Jing Wang, Thomas G. Brink, WeiKang Zheng, Alexei V. Filippenko, Yi Yang, Jianyan Wei, Y. Sophia Dai, Zi-Jian Li, Zizhao He, Chengzi Jiang, Alexei Moiseev and Sergey Kotov, May 9, 2024, The Letters of the Astrophysical Journal.
DOI: 10.3847/2041-8213/ad4357