Galaxy And Mass Assembly: A new approach to quantifying dust in galaxies

TL;DR

This paper presents a novel method combining Balmer decrement and dust mass measurements to better understand dust geometry in galaxies, revealing new insights into dust distribution and its impact on galaxy observations.

Contribution

Introduces new parameters linking Balmer decrement and dust mass to probe dust geometry in galaxies, supporting the maximal foreground screen model.

Findings

New metrics sensitive to dust optical thickness

Variation of dust geometry parameters with galaxy properties

Support for the maximal foreground screen dust model

Abstract

We introduce a new approach to quantifying dust in galaxies by combining information from the Balmer decrement (BD) and the dust mass ($M_d$). 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 $M_d$ by using star formation rate sensitive luminosities at several wavelengths (ultraviolet, H$\alpha$, and far-infrared). This analysis shows that combining the BD and $M_d$ 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.