On the different levels of dust attenuation to nebular and stellar light in star-forming galaxies

TL;DR

This study compares dust attenuation levels toward stellar and nebular light in local star-forming galaxies, revealing trends related to galaxy mass, star formation rate, and position relative to the main sequence, using AKARI, SDSS, GALEX, and WISE data.

Contribution

It provides new insights into how dust attenuation varies between stellar and nebular regions across different galaxy properties and star formation stages.

Findings

More massive galaxies have higher nebular attenuation.

Galaxies with higher specific SFR have lower extra attenuation.

Attenuation levels vary across the SFR-Mstar plane, especially below the main sequence.

Abstract

As a science verification study of the newly released AKARI/FIS Faint Source Catalog ver.1, this paper discusses the different levels of dust attenuation toward stellar light and nebular emission lines within local star-forming galaxies at 0.02<z<0.10. By constructing an updated version of the AKARI-SDSS-GALEX matched galaxy catalog (with >2,000 sources), we compare the dust attenuation levels toward stellar light (from L(IR)/L(UV) ratio) and nebular emission lines (from H-alpha/H-beta ratio). We find that there is a clear trend that more massive galaxies tend to have higher "extra" attenuation toward nebular regions, while galaxies with higher specific star formation rates tend to have lower extra attenuation. We also confirm these trends by using the WISE mid-infrared photometry with a significantly large sample size of the WISE-SDSS-GALEX galaxies (>50,000 sources). Finally, we study how the levels of extra attenuation toward nebular regions change across the SFR-Mstar plane. We find that, even at a fixed stellar mass, galaxies located below the main sequence tend to have higher levels of extra attenuation toward nebular regions, suggesting the change in dust geometry within the galaxies across the star-forming main sequence during the course of star formation quenching process.