Research

HiFAST pipeline

HiFAST is the HI data calibration and imaging pipeline for FAST. I work on the pipeline's data-quality side: standing wave (ripple) removal and RFI flagging, which matter most for faint, diffuse HI.

• Yingjie Jing, Jie Wang, Chen Xu et al. HiFAST: An H i data calibration and imaging pipeline for FAST, Sci. China PMA 67, 259514 (2024) link
• Ziming Liu, Jie Wang, Yingjie Jing, Zhiyu Zhang, Chen Xu et al. HiFAST II. Flux Density Calibration, RAA (2024) link
• Chen Xu, Jie Wang, Yingjie Jing et al. HiFAST III. Standing Wave Removal, RAA 25 015011 (2025) link
• Qingze Chen, Jie Wang, Yingjie Jing, Ligang Hou, Chen Xu et al. HiFAST IV: The stray-radiation correction, Chin. Phys. B 35 059501 (2026) link

HI gas content and star formation

Neutral hydrogen (HI) is the fuel for star formation in galaxies. Using the deep HI data of the FAST-HD² Survey (Hundred-deg² HI Deep Survey) together with DESI optical data, I study the HI content of low-redshift galaxies and how it connects to their stellar properties and star formation. The full survey is designed to map a contiguous ~100 deg² region within the DESI DR1 footprint, with an effective integration time of 20 minutes per beam and a uniform detection sensitivity of 0.28 mJy beam^-1 at 4.8 km s^-1 resolution.

HD² Survey website ↗

• Chen Xu, Jie Wang, Yingjie Jing et al. The FAST Hundred-deg² H I Deep (HD²) Survey: Early Results from the Pilot Survey, ApJS 285 25 (2026) link

Diffuse HI gas around M31

With the deep FAST-M31 HI observations, I study the distribution of the diffuse HI gas in the outer disk of our neighbor galaxy Andromeda (M31), where the HI column density drops to the order of 10^17–18 cm^-2.

M31 Survey website ↗

• Chen Xu, Jie Wang, Yingjie Jing et al. Detection of the HI disk of M31 to a radius of 63 kpc, in prep

Pingtang FAST

The Five-hundred-meter Aperture Spherical Telescope in Guizhou. I work with its HI 21 cm data for the HD² Survey and the FAST-M31 survey.

Xinglong 2.16 m telescope

Optical spectroscopy with BFOSC.

Lijiang 2.4 m telescope

Integral-field observations with the CHILI IFU.