We introduce a new approach to quantifying dust in galaxies by combining information from the Balmer decrement (BD) and the dust mass (Md). While there is no explicit correlation between these two properties, they jointly probe different aspects of the dust present in galaxies. We explore two new parameters that link BD with Md by using star formation rate sensitive luminosities at several wavelengths (ultraviolet, Hα, and far-infrared). This analysis shows that combining the BD and Md in these ways provides new metrics that are sensitive to the degree of optically thick dust affecting the short wavelength emission. We show how these new ''dust geometry'' parameters vary as a function of galaxy mass, star formation rate, and specific star formation rate. We demonstrate that they are sensitive probes of the dust geometry in galaxies, and that they support the ''maximal foreground screen'' model for dust in starburst galaxies.
@article{arxiv.2505.13797,
title = {Galaxy And Mass Assembly: A new approach to quantifying dust in galaxies},
author = {B. Farley and U. T. Ahmed and A. M. Hopkins and M. Cowley and A. Battisti and S. Casura and Y. Gordon and B. W. Holwerda and S. Phillipps and C. Robertson and T. Zafar},
journal= {arXiv preprint arXiv:2505.13797},
year = {2025}
}