Estimating Dust Attenuation From Galactic Spectra. II. Stellar and Gas Attenuation in Star-forming and Diffuse Ionized Gas Regions in MaNGA

Abstract

Abstract We investigate the dust attenuation in both stellar populations and ionized gas in kiloparsec-scale regions in nearby galaxies using integral field spectroscopy data from MaNGA MPL-9. We identify star-forming (H ii) and diffuse ionized gas (DIG) regions from MaNGA data cubes. From the stacked spectrum of each region, we measure the stellar attenuation, E B − V star , using the technique developed by Li et al., as well as the gas attenuation, E B − V gas , from the Balmer decrement. We then examine the correlation of E B − V star , E B − V gas , E B − V gas − E B − V star , and E B − V star / E B − V gas with 16 regional/global properties, and for regions with different Hα surface brightnesses (ΣHα ). We find a stronger correlation between E B − V star and E B − V gas in regions of higher ΣHα . The luminosity-weighted age (t L ) is found to be the property that is the most strongly correlated with E B − V star , and consequently, with E B − V gas − E B − V star and E B − V star / E B − V gas . At fixed ΣHα , log 10 t L is linearly and negatively correlated with E B − V star / E B − V gas at all ages. Gas-phase metallicity and ionization level are important for the attenuation in the gas. Our results indicate that the ionizing source for DIG regions is likely distributed in the outskirts of galaxies, while for H ii regions, our results can be well explained by the two-component dust model of Charlot & Fall.