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Title: Diffuse ionized gas and its effects on nebular metallicity estimates of star-forming galaxies

Abstract

ABSTRACT We investigate the impact of the diffuse ionized gas (DIG) on abundance determinations in star-forming (SF) galaxies. The DIG is characterized using the H α equivalent width (WH α). 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 WH α ≳ 10 Å (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 $$\, \gt 90\, 000$$ 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 β)/([N ii]/H α) index, but reaches ∼0.1 dex at the high-metallicity end for [N ii]/H α. (2) This result is based on the ∼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]/Hα index, O/H increases with SFR at high stellar mass, contrary to previous claims.

Authors:
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [3]; ORCiD logo [4]; ORCiD logo [3]; ORCiD logo [3]; ORCiD logo [5];  [3]
  1. Departamento de Física–CFM, Universidade Federal de Santa Catarina, C.P. 476, 88040-900 Florianópolis, SC, Brazil, School of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews KY16 9SS, UK
  2. Departamento de Física–CFM, Universidade Federal de Santa Catarina, C.P. 476, 88040-900 Florianópolis, SC, Brazil, Centro de Astronomía (CITEVA), Universidad de Antofagasta, Avenida Angamos 601, Antofagasta, 02800, Chile
  3. Departamento de Física–CFM, Universidade Federal de Santa Catarina, C.P. 476, 88040-900 Florianópolis, SC, Brazil
  4. LUTH, CNRS, Observatoire de Paris, PSL University, F-92195, France
  5. Departamento de Física–CFM, Universidade Federal de Santa Catarina, C.P. 476, 88040-900 Florianópolis, SC, Brazil, Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, R. do Matão 1226, 05508-090 São Paulo, Brazil
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1564335
Resource Type:
Published Article
Journal Name:
Monthly Notices of the Royal Astronomical Society
Additional Journal Information:
Journal Name: Monthly Notices of the Royal Astronomical Society Journal Volume: 489 Journal Issue: 4; Journal ID: ISSN 0035-8711
Publisher:
Oxford University Press
Country of Publication:
United Kingdom
Language:
English

Citation Formats

Vale Asari, N., Couto, G. S., Cid Fernandes, R., Stasińska, G., de Amorim, A. L., Ruschel-Dutra, D., Werle, A., and Florido, T. Z. Diffuse ionized gas and its effects on nebular metallicity estimates of star-forming galaxies. United Kingdom: N. p., 2019. Web. doi:10.1093/mnras/stz2470.
Vale Asari, N., Couto, G. S., Cid Fernandes, R., Stasińska, G., de Amorim, A. L., Ruschel-Dutra, D., Werle, A., & Florido, T. Z. Diffuse ionized gas and its effects on nebular metallicity estimates of star-forming galaxies. United Kingdom. doi:10.1093/mnras/stz2470.
Vale Asari, N., Couto, G. S., Cid Fernandes, R., Stasińska, G., de Amorim, A. L., Ruschel-Dutra, D., Werle, A., and Florido, T. Z. Thu . "Diffuse ionized gas and its effects on nebular metallicity estimates of star-forming galaxies". United Kingdom. doi:10.1093/mnras/stz2470.
@article{osti_1564335,
title = {Diffuse ionized gas and its effects on nebular metallicity estimates of star-forming galaxies},
author = {Vale Asari, N. and Couto, G. S. and Cid Fernandes, R. and Stasińska, G. and de Amorim, A. L. and Ruschel-Dutra, D. and Werle, A. and Florido, T. Z.},
abstractNote = {ABSTRACT We investigate the impact of the diffuse ionized gas (DIG) on abundance determinations in star-forming (SF) galaxies. The DIG is characterized using the H α equivalent width (WH α). 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 WH α ≳ 10 Å (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 $\, \gt 90\, 000$ 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 β)/([N ii]/H α) index, but reaches ∼0.1 dex at the high-metallicity end for [N ii]/H α. (2) This result is based on the ∼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]/Hα index, O/H increases with SFR at high stellar mass, contrary to previous claims.},
doi = {10.1093/mnras/stz2470},
journal = {Monthly Notices of the Royal Astronomical Society},
number = 4,
volume = 489,
place = {United Kingdom},
year = {2019},
month = {9}
}

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