China’s Sky Eye Creates Unprecedented Hydrogen Catalog

A team of Chinese astronomers utilizing the Five-hundred-meter Aperture Spherical Radio Telescope (FAST), also known as the “China Sky Eye,” has compiled the largest high-quality catalog of neutral hydrogen (HI) sources beyond our Galaxy.

Hydrogen, the elemental backbone of the universe, plays a pivotal role in the formation and dynamics of galaxies, making this catalog a significant leap in our understanding of the cosmos.

The primary goal of this groundbreaking endeavor is to measure the abundance and kinematics of neutral hydrogen through the 21-centimeter emission line. Such data holds the potential to unravel various astrophysical mysteries, including insights into the properties of dark matter, the existence of faint unknown galaxies, and the structure and evolution of the cosmic landscape.

This colossal initiative is part of the FAST All Sky HI survey (FASHI), aiming to comprehensively cover the entire sky visible to the China Sky Eye. The recently unveiled catalog comprises 41,741 HI sources, surpassing both global quantity and quality standards. Spanning the period from August 2020 to June 2023, these findings mark a significant milestone in extragalactic research.

The Five-hundred-meter Aperture Spherical Radio Telescope stands as the world’s largest single-dish radio telescope, boasting a reception area equivalent to 30 standard football fields. Located in the natural expanse of southwest China’s Guizhou Province, FAST commenced operations on January 11, 2020. Its optimal design provides higher spectral and spatial resolution, extensive coverage, and unparalleled data quality for HI surveys.

As FASHI progresses, it is anticipated to yield the largest extragalactic HI catalog, offering an objective perspective on the HI content and large-scale structure within the local universe. Covering approximately 35 percent of the sky in its current results, the survey is projected to document over 100,000 HI sources over the next five years.

The findings from this remarkable study were recently published in the esteemed journal SCIENCE CHINA Physics, Mechanics and Astronomy. Researchers from Guizhou University, the National Astronomical Observatories under the Chinese Academy of Sciences, and Peking University collaborated on this project. Lister Staveley-Smith, a professor from the University of Western Australia and a peer reviewer, lauded the work as an “impressive milestone” in our cosmic exploration.