Status and perspectives of the CRAFTS extra-galactic HI survey

TL;DR

The paper discusses the CRAFTS survey using FAST, highlighting its capabilities to detect over 600,000 HI galaxies up to redshift 0.35, and its potential to advance understanding of cosmic baryons and satellite populations.

Contribution

It provides empirical beam and sensitivity measurements for FAST and estimates the survey's galaxy detection potential using simulations, outlining its scientific prospects.

Findings

Over 600,000 HI galaxies detectable below redshift 0.35

Complete HIMF above 10^9.5 M_sun below redshift 0.07

FAST's survey will explore environmental and redshift effects on HIMF

Abstract

The Five-hundred-meter Aperture Spherical radio Telescope(FAST) is expected to complete its commissioning in 2019. FAST will soon begin the Commensal Radio Astronomy FasT Survey(CRAFTS), a novel and unprecedented commensal drift scan survey of the entire sky visible from FAST. The goal of CRAFTS is to cover more than 20000 $deg^{2}$ and reach redshift up to about 0.35. We provide empirical measurements of the beam size and sensitivity of FAST across the 1.05 to 1.45 GHz frequency range of the FAST L-band Array of 19-beams(FLAN). Using a simulated HI-galaxy catalogue based on the HI Mass Function(HIMF), we estimate the number of galaxies that CRAFTS may detect. At redshifts below 0.35, over $6\, \times \, 10^{5}$ HI galaxies may be detected. Below the redshift of 0.07, the CRAFTS HIMF will be complete above a mass threshold of $10^{9.5}\,M_{\odot}$. FAST will be able to investigate the environmental and redshift dependence of the HIMF to an unprecedented depth, shedding light onto the missing baryon and missing satellite problems.