Surface Brightness Fluctuations from archival ACS images: a stellar population and distance study

TL;DR

This study uses archival ACS images to analyze surface brightness fluctuations and integrated magnitudes in galaxies, providing insights into stellar populations and galaxy metallicity gradients.

Contribution

It demonstrates that multiband optical SBF data and colors can constrain galaxy stellar metallicity but not age for systems older than 3 Gyr, and explores SBF gradients and metallicity variations.

Findings

SBF and color data constrain stellar metallicity in galaxies.

Detection of SBF color gradients indicates metallicity gradients.

More massive galaxies have higher metallicity in their inner regions.

Abstract

We derive Surface Brightness Fluctuations (SBF) and integrated magnitudes in the V- and I-bands using Advanced Camera for Surveys (ACS) archival data. The sample includes 14 galaxies covering a wide range of physical properties: morphology, total absolute magnitude, integrated color. We take advantage of the latter characteristic of the sample to check existing empirical calibrations of absolute SBF magnitudes both in the I- and V-passbands. Additionally, by comparing our SBF and color data with the Teramo-SPoT simple stellar population models, and other recent sets of population synthesis models, we discuss the feasibility of stellar population studies based on fluctuation magnitudes analysis. The main result of this study is that multiband optical SBF data and integrated colors can be used to significantly constrain the chemical composition of the dominant stellar system in the galaxy, but not the age in the case of systems older than 3 Gyr. SBF color gradients are also detected and analyzed. These SBF gradient data, together with other available data, point to the existence of mass dependent metallicity gradients in galaxies, with the more massive objects showing a non--negligible SBF versus color gradient. The comparison with models suggests that such gradients imply more metal rich stellar populations in the galaxies' inner regions with respect to the outer ones.