On the Thermally Pulsing Asymptotic Giant Branch Contribution to the Light of Nearby Disk Galaxies

TL;DR

This paper investigates how thermally pulsing asymptotic giant branch (TP-AGB) stars contribute to the light of nearby disk galaxies, revealing variability linked to galaxy type and metallicity effects.

Contribution

It provides a detailed analysis of TP-AGB luminosity contributions using pixel-by-pixel modeling across multiple galaxies, highlighting the variability and potential metallicity dependence.

Findings

Preference for low TP-AGB luminosity contribution in most pixels

Significant fraction of pixels favor high TP-AGB contribution

Variation of TP-AGB contribution with galaxy Hubble type

Abstract

The study of the luminosity contribution from thermally pulsing asymptotic giant branch (TP-AGB) stars to the stellar populations of galaxies is crucial to determine their physical parameters (e.g., stellar mass and age). We use a sample of 84 nearby disk galaxies to explore diverse stellar population synthesis models with different luminosity contributions from TP-AGB stars. We fit the models to optical and near-infrared (NIR) photometry, on a pixel-bypixel basis. The statistics of the fits show a preference for a low-luminosity contribution (i.e., high mass-to-light ratio in the NIR) from TP-AGB stars. Nevertheless, for 30 percent to 40 percent of the pixels in our sample a high-luminosity contribution (hence low mass-to-light ratio in the NIR) from TP-AGB stars is favored. According to our findings, the mean TP-AGB star luminosity contribution in nearby disk galaxies may vary with Hubble type. This may be a consequence of the variation of the TP-AGB mass-loss rate with metallicity, if metal-poor stars begin losing mass earlier than metal-rich stars, because of a pre-dust wind that precedes the dust-driven wind.