FEASTS
FEASTS (FAST Extended-Atlas-of-Selected-Targets Survey) is a large image survey of extended HI in/surrounding galaxies in the Local Volume. It takes advantage of the high sensitivity and low side-lobe of FAST (Five-hundred-meter Aperture Spherical radio Telescope) in China, and aims to map the extended and low-surface density HI, which is typically missed in interferometric observations.
FEASTS studies the evolution of Local Volume galaxies with grand HI disks. The major science goals include but are not limited to the following:
- A bench mark sample for studying the Local Volume galaxies.
- A census of diffuse HI and HI clouds in the IGM/CGM of galaxies.
- A statistical measure of HI radial profiles in/above the CGM-disk interface.
- Modification to the star formation law and star formation theories.
- Footprints of stellar and AGN feedbacks in the diffuse HI.
- A new census of HI-rich dwarf satellites.
- Environmental effects that accrete or deplete gas in galaxies.
- The continuity equation of baryonic flow from the CGM to the ISM.
The survey is going to map with 6 drift-scan depth: A flux-complete sample of 118 galaxies whose HI disks can be resolved by FAST. The observation uses a fast-OTF mode, with speed equivalent to drift, and cover the same field multiple (>=5) times to reduce the contamination from RFI and other artifacts.
History of the program as a function of look-back time:
Aug 2022-Aug 2023, observations 2023.
- The team is going to map 15-20 well-resolved nearby galaxies, which have characteristic RHI>3FWHM the PSF of FAST, or have signature of extended but unconfirmed HI in the literature. All these galaxies have existing interferometric HI images.
Aug 2021-Aug 2022, observations 2022.
- The team has mapped 20 well-resolved nearby galaxies, which have characteristic RHI>3FWHM the PSF of FAST, or have signature of extended but unconfirmed HI in the literature. All these galaxies have existing interferometric HI images. The observations reached a planned 5-sigma limit N_HI~ 10^17.9 cm^2 (20 km/s line widths assumed).An atlas of 10 galaxies observed is shown at the top of this page.
- Below, we highlight the FAST(FEASTS)+WSRT(HALOGAS) combined HI image of the NGC 4631 group, and a video comparing the 3d views of the two datasets. A detailed study of this system is present in (Wang et al. 2023), and summarized here. The data is released on the Data Release Page.
Active working groups
(Names of captains highlighted)
TWG1: FAST HI data observation & processing
Yingjie Jing, Ziming Liu, Lister Staveley-Smith, Jie Wang, Jing Wang, Shun Wang, Dong Yang
TWG2: interferometric HI data, FAST+interferometric data combination
Xinkai Chen, Kelley Hess, Lister Staveley-Smith, Ran Wang, Jing Wang, Fabian Walter
TWG3: multi-wavelength data
Cheng Li, Xuchen Lin, Li Shao, Ran Wang, Zhimin Zhou, Hu Zou
Team of Organization
Jie Wang (co-PI), Jing Wang (co-PI), Dong Yang (project manager)
More information
Detailed progress of the program, including the sample list and observational arrangements, can be found in the github page of FEASTS .
The team helds an open and collaborative altitude, and data will be released here within 2 years or sooner upon publication of related papers.
We also conduct a sister program FEASTS-env which studies the evolution of galaxies in groups and clusters. We got good data for the N4636 group (Lin et al. in prep), and detected some new galaxies in the Coma cluster. The N4636 observation was part of a synergetic program with ASKAP-WALLABY.