The "China Sky Eye" ultra-deep field survey discovered the farthest neutral hydrogen galaxy, a "blind search" in depth
Taking advantage of its high sensitivity and large field of view, the "China Sky Eye" discovered a batch of the most distant neutral hydrogen galaxy samples in the ultra-deep field survey project, providing evidence that there were more massive neutral hydrogen galaxies in the universe 4.2 billion years ago. Observational evidence. On May 10, the results were published online in the international scientific journal "Astrophysics Letters".
Hydrogen is the earliest element to form in the universe and usually exists as neutral hydrogen. Neutral hydrogen is an important component of gas circulation in galaxies, provides fuel for star formation regions, and is also an important probe for studying the dynamic structure of galaxies. The neutral hydrogen rotation curve provides observational evidence for the existence of dark matter and provides a solid foundation for the establishment of the standard universe model.
Previously, the Parkes 64-meter radio telescope in Australia and the Arecibo 305-meter radio telescope in the United States detected about 5,000 and 30,000 neutral hydrogen galaxies respectively. These galaxy samples gave the mass distribution of neutral hydrogen galaxies for the first time, allowing astronomers to systematically study neutral hydrogen galaxies. The relationship between hydrogen gas, stellar mass and star formation rate.
![The "China Sky Eye" ultra-deep field survey discovered the farthest neutral hydrogen galaxy, a "blind search" in depth](https://a5qu.com/upload/images/c893f06eecb4dded75ce30ad7f2c6877.webp)
The FAST ultra-deep field survey project led by Peng Bo, a researcher at the National Astronomical Observatory of the Chinese Academy of Sciences, takes full advantage of FAST's high sensitivity and the large field of view of the 19-beam receiver to conduct a deep "blind search" for distant and faint neutral hydrogen galaxies. In the pilot survey, the project team discovered six neutral hydrogen galaxies about 5 billion light-years away. This is the most distant sample of neutral hydrogen galaxies ever directly detected using the 21 cm emission line, and one of the galaxies has the largest neutral hydrogen mass yet.
The most distant neutral hydrogen galaxy discovered by FAST
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 the dark energy spectrometer spectral line data of their collaborators and multi-band observations from multiple optical telescopes, they successfully found the optical counterparts of these six distant neutral hydrogen galaxies. This shows that in the detection of distant galaxies, FAST provides a new way to detect distant neutral hydrogen galaxies.
![The "China Sky Eye" ultra-deep field survey discovered the farthest neutral hydrogen galaxy, a "blind search" in depth](https://a5qu.com/upload/images/c25724b5ed674554d3ce62c8bf206e0c.webp)