The Chinese Eye has made a new discovery. Reporters learned from the National Astronomical Observatory of the Chinese Academy of Sciences on the 10th that, based on the observation data of the "China Celestial Eye" FAST, an international research team led by Chinese researchers has found a batch of samples of the most distant neutral hydrogen galaxies so far. The relevant research results are published online in the Astrophysical Journal Newsletter. Hydrogen is the earliest formed element in the universe, usually existing in the form of neutral hydrogen. Neutral hydrogen is also an important component of gas circulation in galaxies, providing fuel for star forming regions and serving as an important probe for studying the dynamic structure of galaxies. The neutral hydrogen rotation curve provides observational evidence for the existence of dark matter, providing a solid foundation for the establishment of the standard universe model. Previously, the Australian Parks Radio Telescope searched for galaxies within 600 million light-years in the southern hemisphere and detected approximately 5000 neutral hydrogen galaxies. The Arecibo Radio Telescope in the United States searched for galaxies within 800 million light-years in the northern hemisphere and detected approximately three neutral hydrogen galaxies. These galaxy samples provide for the first time the mass distribution of neutral hydrogen galaxies, allowing astronomers to systematically study the relationship between neutral hydrogen gas and stellar mass and star formation rate. This time, Peng Bo, a researcher at the National Astronomical Observatory of the Chinese Academy of Sciences, presided over the "China Tianyan" ultra deep field survey project team, carried out a deep "blind search" for distant and weak neutral hydrogen galaxies. "We discovered six neutral hydrogen galaxies approximately 5 billion light-years away from Earth during our sky survey, which is the farthest sample of neutral hydrogen galaxies detected directly with a 21 centimeter emission line to date. One galaxy has the largest neutral hydrogen mass to date," said Bloomberg. The project team estimated the density of massive neutral hydrogen galaxies in the sample and found that there were more massive neutral hydrogen galaxies in the universe 4.2 billion years ago. Through joint observations with large optical telescopes from the United States and Russia, researchers have successfully identified the optical counterparts of these six long-range neutral hydrogen galaxies. This means that the "Chinese Eye" provides a new way to explore distant neutral hydrogen galaxies. (Lai Xin She)