The FASHI survey used the FAST telescope to map 35% of the target sky area and discovered more than 41,000 extragalactic HI sources, earning widespread praise in the astronomical community. The FAST All-Sky HI Survey (FASHI) aims to cover the entire sky observable by the Five Hundred Meter Aperture Spherical Radio Telescope (FAST), covering approximately 22,000 square degrees of declination between -14 degrees and +66 degrees, with a frequency range of 1050-1450 MHz, and is expected to eventually detect more than 100,000 HI sources.

Promotional images show the project related to the Five Hundred Meter Aperture Spherical Radio Telescope (FAST) All-Sky HI Survey (FASHI). As shown, the powerful FAST telescope is observing distant galaxies, recording their high radiation and revealing the detailed physical properties of the galaxies.

From August 2020 to June 2023, FASHI’s observation range exceeds 7,600 square degrees, accounting for approximately 35% of the total observable sky area of ​​FAST. The FASHI team detected a total of 41,741 extragalactic HI sources in the frequency range 1305.5-1419.5MHz. Once the FASHI team completes this work, it will provide the largest extragalactic HI catalog and objectively demonstrate the content and large-scale structure of HI in the local universe.

Lister Staveley-Smith, a peer reviewer of the paper and a professor at the University of Western Australia, called their work an "impressive milestone": "This is an extremely important contribution to astronomical research, especially the field of galaxy evolution."

The FASHI sky distribution of the currently published 41,741 HI sources (blue dots) in the Galactic hemisphere shows the roughness introduced by practical and timing constraints. For ease of comparison, ALFALFAα100 (Haynes et al., 2018) and HIPASS galaxies (Koribalski et al., 2004; Meyer et al., 2004; Wong et al., 2006) are also represented by red and green dots, respectively. The two black dashed lines indicate the position of the Milky Way plane at galactic latitude b = ±10deg.

Hélène Courtois, professor at the University of Lyon 1, expressed her appreciation for their work: "This paper is good news for projects like "Cosmic Flows"! I had no idea that the FASHI survey had been carried out for 3 years! The quality of the spectra shown is very high, the integrity of the sample is amazing, and it also shows the extremely high sensitivity of the instrument. The area surveyed in only 3 years gives high hope that FAST can cover the entire sky in record time!"

"The paper was completely unexpected, and I read it page by page like a child slowly and joyfully opening a Christmas present."

The work, recently published in the journal Science China's Physics, Mechanics and Astronomy, involved researchers from Guizhou University, the National Astronomical Observatory of the Chinese Academy of Sciences and Peking University.

Compiled source: ScitechDaily