Galaxy and Mass Assembly (GAMA): Dust obscuration in galaxies and their recent star formation histories

TL;DR

This study derives star formation rates for GAMA galaxies using multi-wavelength data, evaluates dust correction methods, and explores how dust obscuration varies with star formation activity, providing insights into galaxy evolution.

Contribution

It introduces an optimal dust obscuration correction method based on the Balmer decrement and compares different extinction laws for accurate SFR estimation.

Findings

Fischera and Dopita (2005) curve with Rv=4.5 best matches SFR indicators.

Removing the 2200A feature from the extinction curve improves consistency.

UV dust obscuration correlates strongly with star formation rate.

Abstract

We present self-consistent star formation rates derived through pan-spectral analysis of galaxies drawn from the Galaxy and Mass Assembly (GAMA) survey. We determine the most appropriate form of dust obscuration correction via application of a range of extinction laws drawn from the literature as applied to Halpha, [O{II}] and UV luminosities. These corrections are applied to a sample of 31,508 galaxies from the GAMA survey at z < 0.35. We consider several different obscuration curves, including those of Milky Way, Calzetti (2001) and Fischera and Dopita (2005) curves and their effects on the observed luminosities. At the core of this technique is the observed Balmer decrement, and we provide a prescription to apply optimal obscuration corrections using the Balmer decrement. We carry out an analysis of the star formation history (SFH) using stellar population synthesis tools to investigate the evolutionary history of our sample of galaxies as well as to understand the effects of variation in the Initial Mass Function (IMF) and the effects this has on the evolutionary history of galaxies. We find that the Fischera and Dopita (2005) obscuration curve with an R_{v} value of 4.5 gives the best agreement between the different SFR indicators. The 2200A feature needed to be removed from this curve to obtain complete consistency between all SFR indicators suggesting that this feature may not be common in the average integrated attenuation of galaxy emission. We also find that the UV dust obscuration is strongly dependent on the SFR.