The Wyoming Survey for H-alpha. III. A Multi-wavelength Look at Attenuation by Dust in Galaxies out to z~0.4

TL;DR

This study uses multi-wavelength data from the Wyoming Survey for H-alpha, Spitzer, and GALEX to analyze how dust attenuation in star-forming galaxies evolves up to redshift 0.4, revealing a mild decrease over time.

Contribution

It introduces a combined multi-wavelength approach to measure dust attenuation evolution using a new SFR indicator and compares it with traditional methods.

Findings

Dust attenuation remains relatively constant on average across epochs.

Higher star formation rates correlate with greater dust attenuation at each epoch.

A mild decrease in dust attenuation with increasing redshift is observed at fixed star formation rates.

Abstract

We report results from the Wyoming Survey for H-alpha (WySH), a comprehensive four-square degree survey to probe the evolution of star-forming galaxies over the latter half of the age of the Universe. We have supplemented the H-alpha data from WySH with infrared data from the Spitzer Wide-area Infrared Extragalactic (SWIRE) Survey and ultraviolet data from the Galaxy Evolution Explorer (GALEX) Deep Imaging Survey. This dataset provides a multi-wavelength look at the evolution of the attenuation by dust, and here we compare a traditional measure of dust attenuation (L(TIR)/L(FUV)) to a diagnostic based on a recently-developed robust star formation rate (SFR) indicator, [H-alpha_obs+24-micron]/H-alpha_obs. With such data over multiple epochs, the evolution in the attenuation by dust with redshift can be assessed. We present results from the ELAIS-N1 and Lockman Hole regions at z~0.16, 0.24, 0.32 and 0.40. While the ensemble averages of both diagnostics are relatively constant from epoch to epoch, each epoch individually exhibits a larger attenuation by dust for higher star formation rates. Hence, an epoch to epoch comparison at a fixed star formation rate suggests a mild decrease in dust attenuation with redshift.