Variation of the Nebular Dust Attenuation Curve with the Properties of Local Star-forming Galaxies

TL;DR

This study analyzes a large sample of local star-forming galaxies to determine the nebular dust attenuation curve and finds it to be remarkably consistent across different galaxy properties, suggesting a universal shape.

Contribution

It provides the first detailed measurement of the nebular dust attenuation curve for a large local galaxy sample and shows its shape is nearly invariant with galaxy properties.

Findings

The nebular attenuation curve is similar to the Milky Way and SMC curves.

Little variation in the curve's shape across different galaxy properties.

Supports a universal nebular dust attenuation curve for star-forming galaxies.

Abstract

We use a sample of $78,340$ star-forming galaxies at $z\simeq 0.04-0.1$ from the SDSS DR8 survey to calculate the average nebular dust attenuation curve and its variation with the physical properties of galaxies. Using the first four low-order Balmer emission lines (H$\alpha$, H$\beta$, H$\gamma$, H$\delta$) detected in the composite spectrum of all galaxies in the sample, we derive a nebular attenuation curve in the range of $0.41\,\mu$m to $0.66\,\mu$m that has a similar shape and normalization to that of the Galactic extinction curve (Milky Way curve), the SMC curve and the nebular attenuation curve derived recently for typical star-forming galaxies at $z\sim2$. We divide the galaxies into bins of stellar mass, gas-phase metallicity, and specific star-formation rate, and derive the nebular attenuation curve in each of these bins. This analysis indicates that there is very little variation in the shape of the nebular dust attenuation curve with the properties used to bin the galaxies, and suggests a near universal shape of the nebular dust attenuation curve at least among the galaxies and the range of properties considered in our sample.