- FAST has created the largest map of neutral hydrogen sources ever, aiding the understanding of galaxy formation and evolution.
- Neutral hydrogen is the raw material for the development of stars and galaxies, providing information about cosmic evolution.
- The new dataset, FASHI DR2, has nearly four times the number of detections compared to earlier data, surpassing the record of the Arecibo Observatory.
- The latest observations will promote international collaboration and contribute to research on galaxy evolution and cosmic structure.
China's Five-Hundred-Metre Aperture Spherical Radio Telescope (FAST) has achieved a significant breakthrough in astronomy. According to reports, FAST has created the largest map of neutral hydrogen sources ever made, a milestone that marks a major step forward in understanding how galaxies form, evolve, and interact on the grandest scales. The reports indicate that FAST detected 156,411 neutral hydrogen sources over two years of observations, covering approximately 19,500 square degrees of the sky, nearly half of the celestial sphere.
Neutral hydrogen is one of the most fundamental substances in the universe, often described as the raw material for the development of stars and galaxies, and it also retains information about cosmic evolution. Astronomers can detect neutral hydrogen through the 21-centimetre radio emission it produces. Unlike visible light, this wavelength of radio wave can penetrate large amounts of cosmic dust, allowing scientists to observe gas that might otherwise be hidden. Due to its enormous collecting area and high sensitivity, FAST is particularly well-suited for this task, and its observations provide astronomers with a powerful tool to study the distribution of hydrogen and, consequently, the structure and evolution of galaxies.
The Importance of Neutral Hydrogen
The new dataset represents a significant expansion of FAST's early observations. Named FASHI DR2, the new dataset shows a substantial increase compared to FAST's earlier observations. The telescope's first dataset, released in January 2024, contained 41,741 detections and had already set a world record. The latest survey has increased this number to 156,411, nearly four times the early FAST data. According to reports, FAST has also surpassed the record of the ALFALFA survey conducted by the Arecibo Observatory in the United States, which had been the leading neutral hydrogen survey for nearly two decades.
The Scale of the New Dataset
The scale of the new catalogue is particularly significant because it provides researchers with an unprecedented amount of individual galaxy measurement data. Each detection actually provides scientists with another piece of information about the distribution of matter in the universe. The significance of this project goes far beyond mere galaxy counting. Researchers can use this vast dataset to explore some of the most important questions in modern cosmology. These observations are expected to contribute to research on galaxy formation and evolution, dark matter distribution, and the development of large-scale cosmic structures.
Scientists are also able to extend the measurement of the neutral hydrogen mass function to galaxies with masses of about one million times that of the Sun. Another significant achievement is the measurement of the local density of neutral hydrogen with a statistical accuracy of about 0.6%, which the report describes as the most accurate such measurement to date. Such precise measurements are crucial because even small improvements in astronomical measurements can help scientists test existing theories and refine models of cosmic evolution. The latest catalogue is expected to further promote international cooperation, particularly in the fields of galaxy evolution, cosmology, large-scale cosmic structures, and the identification of potential gravitational wave sources.
The Impact of the FAST Dataset on Astronomy
The breakthroughs achieved by China's Five-Hundred-Metre Aperture Spherical Radio Telescope (FAST) in astronomical research mark a deeper understanding of neutral hydrogen in the universe. As the basic material for galaxy formation, the expansion of observational data on neutral hydrogen not only improves the accuracy of galaxy counting but also provides a new perspective for studying cosmic structure and evolution. Especially with the scale of the new dataset, researchers are able to explore more complex cosmic issues and may promote international scientific cooperation, further advancing the development of cosmology.