reporter learned from of the Chinese Academy of Sciences that recently, an international team led by researcher Xu Cong of the National Observatory of the Chinese Academy of Sciences used the China Sky Eye FAST to image and observe the famous dense galaxy group " Stephen Five-stack Galaxy " and the hydrogen atom gas in the surrounding sky area. discovered a huge atomic gas system with a scale of about 2 million light years, which is 20 times larger than the Milky Way where we are. It is understood that is the largest atomic gas system detected in the universe so far. The result was published in the international academic journal Nature on October 19, 2022, Beijing time.
Observation of gases in the universe is a very important research topic in astrophysics . The origin of all celestial bodies in the universe is inseparable from atomic gas. For example, the main evolutionary process of galaxies is the process of continuously absorbing atomic gas from the universe and converting it into stars. Radio astronomical band can directly observe atomic gases in the universe. The Chinese Sky Eye FAST is the largest and most sensitive single-aperture radio telescope in the world today. It can detect dark and weak radiation emitted by extremely thin diffuse atomic gases far away from the center of the galaxy, opening a new window for studying the origins of celestial bodies in the universe.
FAST This latest discovery reveals the existence of a large-scale low-density atomic gas structure in the peripheral space far from the center of of the galaxy group. The formation of these gas structures is likely related to the history of intergalactic interactions when the "Stephen Five-layer Galaxy" was formed in the early days, and has existed for about a billion years. This discovery presents challenges studying the evolution of galaxies and their gases in the universe, as existing theories are difficult to explain why, for such a long time, these thin atomic gases have not been ionized by ultraviolet background radiation in the universe. This observation from FAST predicts that there may be more such large-scale low-density atomic gas structures in the universe. The distribution of atomic gases detected in the sky around the famous dense galaxy group "Stephen Five-layer Galaxy" detected by
FAST (displayed with red halo; the thinner halo means the lower the density of the gas column). Since its discovery by French astronomer Stephen in 1877, the "Stephen Five-Step Galaxy" is the most popular galaxy group and has also become one of the five targets for the Webb Space Telescope to observe and display it to the public for the first time. The background in the figure is a color optical image obtained with an optical telescope. Stephen's Five-fold Galaxy is located in the middle of the image. The embedded image is the recently released color chart of the infrared band by Webb Space Telescope: blue and white light represent the stellar radiation in the near-infrared band, and orange and red light represent the gas and dust radiation in the mid-infrared band. Photo provided by the National Observatory
