GBT26B-260

Spatially Resolved Atomic and Molecular Phase Census of the ALMA-FACTS Galaxies

Abstract

We propose to complete the VLA+GBT HI 21-cm observations of all 12 galaxies from the ALMA FACTS CO(1-0) survey by observing 5 galaxies which do not have VLA+GBT HI data. The FACTS sample is a subset of the PHANGS CO(2-1) sample. In the molecular regime, FACTS already shows, in the molecular gas distributions and CO(2-1)/CO(1-0) line ratio, the evolution of the molecular gas physical conditions in galactic structures, especially in bars. The requested VLA+GBT HI data completes the gas evolutionary sequence from the atomic to molecular phases across the galaxies. We will investigate the HI-H2 gas phase evolution, their dynamics, and their relation to star formation across galactic structures on ~subkpc scales. The HI data provides accurate HI surface density, which also provides the accurate H2 surface density by calibrating the CO-to-H2 conversion factor. The VLA observations will be combined with GBT single-dish observations which are queued for the 26A semester. We jointly propose primarily for VLA, but also for GBT in case the GBT observations are not taken. Since the sample overlaps with PHANGS, there is also rich multiwavelength data (JWST, HST, VLT/MUSE, Herschel, Spitzer, etc.) available. The proposed survey adds high-resolution HI data.

Investigators

Name	Institution
Amanda Lee *	Massachusetts Amherst, University of; New York at Stony Brook, State University of
Jin Koda	New York at Stony Brook, State University of
Fumiya Maeda	Osaka Electro-Communication University
Akihiko Hirota	National Astronomical Observatory of Japan
Fumi Egusa	Tokyo, University of
Tsuyoshi Sawada	Joint ALMA Observatory
Shinya Komugi	Japan Aerospace Exploration Agency ; Kogakuin University

* indicates the PI