The TYPHOON Stellar Population Synthesis Survey. II. Pushing Full Spectral Fitting to the Limit in the Nearby Grand Design Barred Spiral M83

TL;DR

This study applies advanced spectral fitting to analyze the stellar populations, dust, and metallicity distribution in galaxy M83, revealing a central metallicity drop and dust features, with results validated by multiple methods.

Contribution

It introduces a detailed spatial analysis of stellar populations and metallicities in M83 using full spectral fitting, including a novel comparison with young stellar probes.

Findings

Metallicity of young stars is supersolar and uniform across the disk.

A central metallicity decrease suggests matter infall or AGN influence.

A dust cavity of 260 pc is confirmed near the galaxy center.

Abstract

We apply population synthesis techniques to analyze TYPHOON long slit spectra of the starburst barred spiral galaxy M83. The analysis covers a central square of 5 arcmin side length. We determine the spatial distribution of dust through the analysis of reddening and extinction, together with star formation rates, ages, and metallicities of young and old stellar populations. For the first time, a spatial one-to-one comparison of metallicities derived from full-spectral fitting techniques with those obtained from individual young stellar probes has been carried out. The comparison with blue supergiant stars, young massive star clusters, and super star clusters shows a high degree of concordance when wavelength coverage in the $B$-band is available. The metallicity of the young population is supersolar and does not show a radial metallicity gradient along the investigated part of the disk, in agreement with our chemical evolution model. However, a notable decrease in metallicity is observed in a tightly confined region at the galaxy center, coinciding with circumnuclear orbits. We attribute this to matter infall either from the circumgalactic medium or a dwarf galaxy interloper or, alternatively, to AGN-interrupted chemical evolution. We confirm the presence of a dust cavity with a diameter of 260~pc close to the galaxy center. Dust absorption and molecular CO emission are spatially well correlated. We find an anticorrelation between R$_V$, the ratio of dust attenuation to reddening, and the emission strength of molecular species present in photo-dissociation regions. We confirm our results by using alternative fitting algorithms and stellar libraries.