On the Origin of Quenched but Gas-rich Regions at Kiloparsec Scales in Nearby Galaxies

• Published in: The Astrophysical journal Vol. 975; no. 1; pp. 17 - 43
• Main Authors: Jing, Tao, Li, Cheng
• Format: Journal Article
• Language: English
• Published: Philadelphia The American Astronomical Society 01.11.2024; IOP Publishing
• Subjects: Active galactic nuclei; Cold gas; Density; Disk galaxies; Galaxies; Galaxy evolution; Galaxy quenching; Gravitational collapse; Parameter identification; Quenching; Radiation pressure; Spectroscopy; Star & galaxy formation; Star formation; Star formation rate; Stars; Stellar evolution; Stellar feedback
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/ad7367

Abstract We use resolved spectroscopy from MaNGA to investigate the significance of both local and global properties of galaxies to the cessation of star formation at kpc scales. Quenched regions are identified from a sample of isolated disk galaxies by a single-parameter criterion D n (4000) - log EW(H α ) > 1.6 − log 2 = 1.3 , and are divided into gas-rich quenched regions (GRQRs) and gas-poor quenched regions according to the surface density of cold gas (Σ gas ). Both types of quenched regions tend to be hosted by non-AGN galaxies with relatively high mass ( M * ≳ 10 10 M ⊙ ) and red colors (NUV − r ≳ 3), as well as low star formation rate and high central density at fixed mass. They span wide ranges in other properties including structural parameters that are similar to the parent sample, indicating that the conditions responsible for quenching in gas-rich regions are largely independent of the global properties of galaxies. We train random forest classifiers and regressors for predicting quenching in our sample with 15 local/global properties. Σ * is the most important property for quenching, especially for GRQRs. These results strongly indicate the important roles of low-mass hot evolved stars, which are numerous and long-lived in quenched regions and can provide substantial radiation pressure to support the surrounding gas against gravitational collapse. The different feature importance for quenching, as found previously by A. F. L. Bluck et al., is partly due to the different definitions of quenched regions, particularly the different requirements on EW(H α ).