Resolved maps of stellar mass and SED of galaxies from optical/NIR imaging and SPS models

TL;DR

This paper presents a method to create detailed stellar mass maps of galaxies using optical and NIR imaging, revealing insights into galaxy structure and mass distribution that are not apparent in traditional photometry.

Contribution

The study introduces a novel approach to derive resolved stellar mass maps from optical/NIR images with high accuracy, accounting for dust and stellar population variations.

Findings

Mass maps are smoother than optical/NIR images.

Unresolved photometry underestimates total stellar mass by up to 40%.

Color correlates with stellar mass density within galaxies.

Abstract

We report on the method developed by Zibetti, Charlot and Rix (2009) to construct resolved stellar mass maps of galaxies from optical and NIR imaging. Accurate pixel-by-pixel colour information (specifically g-i and i-H) is converted into stellar mass-to-light ratios with typical accuracy of 30%, based on median likelihoods derived from a Monte Carlo library of 50,000 stellar population synthesis models that include dust and updated TP-AGB phase prescriptions. Hence, surface mass densities are computed. In a pilot study, we analyze 9 galaxies spanning a broad range of morphologies. Among the main results, we find that: i) galaxies appear much smoother in stellar mass maps than at any optical or NIR wavelength; ii) total stellar mass estimates based on unresolved photometry are biased low with respect to the integral of resolved stellar mass maps, by up to 40%, due to dust obscured regions being under-represented in global colours; iii) within a galaxy, on local scales colours correlate with surface stellar mass density; iv) the slope and tightness of this correlation reflect/depend on the morphology of the galaxy.