Characterizing Stellar and Gas Properties in NGC 628: Spatial Distributions, Radial Gradients, and Resolved Scaling Relations

TL;DR

This study examines the spatial distributions and gradients of gas and stellar properties in NGC 628, revealing insights into galaxy formation, chemical enrichment, and star formation processes through multi-wavelength and spectroscopic data analysis.

Contribution

It provides the first detailed analysis of resolved gas and stellar properties in NGC 628, combining multi-wavelength and spectroscopic data to explore star formation and chemical enrichment.

Findings

NGC 628 is an isolated galaxy with no recent interactions.

Radial metallicity gradient supports inside-out galaxy formation.

Resolved MZR shows no secondary dependence on SFR or H I surface density.

Abstract

Building on our previous research of multi-wavelength data from UV to IR, we employ spectroscopic observations of ionized gas, as well as neutral hydrogen gas obtained from the Five-hundred Meter Aperture Spherical Telescope (FAST), to explore the intrinsic processes of star formation and chemical enrichment within NGC 628. Our analysis focuses on several key properties, including gas-phase extinction, star formation rate (SFR) surface density, oxygen abundance, and H I mass surface density. The azimuthal distributions of these parameters in relation to the morphological and kinematic features of FAST H I reveal that NGC 628 is an isolated galaxy that has not undergone recent interactions. We observe a mild radial extinction gradient accompanied by a notable dispersion. The SFR surface density also shows a gentle radial gradient, characteristic of typical spiral galaxies. Additionally, we find a negative radial metallicity gradient of $-0.44$ dex $R_{25}^{-1}$, supporting the "inside-out" scenario of galaxy formation. We investigate the resolved Mass-Metallicity Relation (MZR) and the resolved Star Formation Main Sequence (SFMS) alongside their dependencies on the physical properties of both ionized and neutral hydrogen gas. Our findings indicate no secondary dependency of the resolved MZR on SFR surface density or H I mass surface density. Furthermore, we observe that gas-phase extinction and the equivalent width of H{\alpha} both increase with SFR surface density in the resolved SFMS.