A Variant Stellar-to-nebular Dust Attenuation Ratio on Subgalactic and Galactic Scales

Zesen Lin; Xu Kong

doi:10.3847/1538-4357/ab5f0e

paper

A Variant Stellar-to-nebular Dust Attenuation Ratio on Subgalactic and Galactic Scales

arXiv:1912.01851 · doi:10.3847/1538-4357/ab5f0e

Abstract

The state-of-the-art geometry models of stars/dust suggest that dust attenuation toward nebular regions ( $A_{V, g a s}$ ) is always larger than that of stellar regions ( $A_{V, s t a r}$ ). Utilizing the newly released integral field spectroscopic data from the MaNGA survey, we investigate whether and how the $A_{V, s t a r} / A_{V, g a s}$ ratio varies from subgalactic to galactic scales. On a subgalactic scale, we report a stronger correlation between $A_{V, s t a r}$ and $A_{V, g a s}$ for more active HII regions. The local $A_{V, s t a r} / A_{V, g a s}$ is found to have moderate nonlinear correlations with three tracers of diffuse ionized gas (DIG), as well as indicators of gas-phase metallicity and ionization. The DIG regions tend to have larger $A_{V, s t a r} / A_{V, g a s}$ compared to classic HII regions excited by young OB stars. Metal-poor regions with a higher ionized level suffer much less nebular attenuation and thus have larger $A_{V, s t a r} / A_{V, g a s}$ ratios. A low- $A_{V, g a s}$ and high- $A_{V, s t a r} / A_{V, g a s}$ sequence, which can be resolved into DIG-dominated and metal-poor regions, on the three BPT diagrams is found. Based on these observations, we suggest that besides the geometry of stars/dust, local physical conditions such as metallicity and ionized level also play an important role in determining the $A_{V, s t a r} / A_{V, g a s}$ . On a galactic scale, the global $A_{V, s t a r} / A_{V, g a s}$ ratio has strong correlations with stellar mass ( $M_{*}$ ), moderate correlations with SFR and metallicity, and weak correlations with inclination and specific SFR. Galaxies with larger $M_{*}$ and higher SFR that are more metal-rich tend to have smaller $A_{V, s t a r} / A_{V, g a s}$ ratios. Such correlations form a decreasing trend of $A_{V, s t a r} / A_{V, g a s}$ along the star-forming main sequence and mass-metallicity relation. The dust growth process accompanied by galaxy growth might be one plausible explanation for our observations.

Accepted for publication in ApJ, updated to match the final version

A Variant Stellar-to-nebular Dust Attenuation Ratio on Subgalactic and Galactic Scales

Abstract

References in corpus (25)

Cited by in corpus (6)