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We investigate the impact of the diffuse ionized gas (DIG) on abundance determinations in star-forming (SF) galaxies. The DIG is characterised using the H$alpha$ equivalent width ($W_{text{H}alpha}$). From a set of 1,409 SF galaxies from the Mapping Nearby Galaxies at APO (MaNGA) survey, we calculate the fractional contribution of the DIG to several emission lines using high-$S/N$ data from SF spaxels (instead of using noisy emission-lines in DIG-dominated spaxels). Our method is applicable to spectra with observed $W_{text{H}alpha} gtrsim 10$ angstroms (which are not dominated by DIG emission). Since the DIG contribution depends on galactocentric distance, we provide DIG-correction formulae for both entire galaxies and single aperture spectra. Applying those to a sample of $,> 90,000$ SF galaxies from the Sloan Digital Sky Survey, we find the following. (1) The effect of the DIG on strong-line abundances depends on the index used. It is negligible for the ([O III]/H$beta$)/([N II]/H$alpha$) index, but reaches $sim 0.1$ dex at the high-metallicity end for [N II]/H$alpha$. (2) This result is based on the $sim$kpc MaNGA resolution, so the real effect of the DIG is likely greater. (3) We revisit the mass-metallicity-star formation rate (SFR) relation by correcting for the DIG contribution in both abundances and SFR. The effect of DIG removal is more prominent at higher stellar masses. Using the [N II]/H$alpha$ index, O/H increases with SFR at high stellar mass, contrary to previous claims.
The Diffuse Ionized Gas (DIG) contributes to the nebular emission of galaxies, resulting in emission line flux ratios that can be significantly different from those produced by HII regions. Comparing the emission of [SII]6717,31 between pointed obser
It has been hypothesized that photons from young, massive star clusters are responsible for maintaining the ionization of diffuse warm ionized gas seen in both the Milky Way and other disk galaxies. For a theoretical investigation of the warm ionized
We present a systematic study of the diffuse ionized gas (DIG) in M83 and its effects on the measurement of metallicity gradients at varying resolution scales. Using spectrophotometric data cubes of M83 obtained at the 2.5m duPont telescope at Las Ca
Estimates of gas-phase abundances based on strong-line methods have been calibrated for H~{scshape ii} regions. Those methods ignore any contribution from the diffuse ionized gas (DIG), which shows enhanced collisional-to-recombination line ratios in
We analyze the intrinsic velocity dispersion properties of 648 star-forming galaxies observed by the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, to explore the relation of intrinsic gas velocity dispersions with star formation