Present-day mass-metallicity relation for galaxies using a new electron temperature method
Present-day mass-metallicity relation for galaxies using a new electron temperature method
Aims. We investigate electron temperature (Te) and gas-phase oxygen abundance (ZTe) measurements for galaxies in the local Universe (z < 0.25). Our sample comprises spectra from a total of 264 emission-line systems, ranging from individual HII regions to whole galaxies, including 23 composite HII regions from star-forming main sequence galaxies in the MaNGA survey. Methods. We utilise 130 of these systems with directly measurable Te(OII) to calibrate a new metallicity-dependent Te(OIII)-Te(OII) relation that provides a better representation of our varied dataset than existing relations from the literature. We also provide an alternative Te(OIII)-Te(NII) calibration. This new Te method is then used to obtain accurate ZTe estimates and form the mass - metallicity relation (MZR) for a sample of 118 local galaxies. Results. We find that all the Te(OIII)-Te(OII) relations considered here systematically under-estimate ZTe for low-ionisation systems by up to 0.6 dex. We determine that this is due to such systems having an intrinsically higher O+ abundance than O++ abundance, rendering ZTe estimates based only on [OIII] lines inaccurate. We therefore provide an empirical correction based on strong emission lines to account for this bias when using our new Te(OIII)-Te(OIII) and Te(OIII)-Te(NII) relations. This allows for accurate metallicities (1σ = 0.08 dex) to be derived for any low-redshift system with an [OIII]λ4363 detection, regardless of its physical size or ionisation state. The MZR formed from our dataset is in very good agreement with those formed from direct measurements of metal recombination lines and blue supergiant absorption lines, in contrast to most other Te-based and strong-line-based MZRs. Our new Te method therefore provides an accurate and precise way of obtaining ZTe for a large and diverse range of star-forming systems in the local Universe.
Galaxies: abundances, HII regions, ISM: abundances
Yates, R. M.
417668a7-0010-4310-bfb1-68fa6b348921
Schady, P.
653a080c-f286-4eef-bc7d-1a1e09644f07
Chen, T. W.
fe907268-49e0-4ae2-9460-657d6b19a8b0
Schweyer, T.
04f77381-d0ec-4cff-8581-4cf59184b3fd
Wiseman, P.
865f95f8-2200-46a8-bd5e-3ee30bb44072
18 February 2020
Yates, R. M.
417668a7-0010-4310-bfb1-68fa6b348921
Schady, P.
653a080c-f286-4eef-bc7d-1a1e09644f07
Chen, T. W.
fe907268-49e0-4ae2-9460-657d6b19a8b0
Schweyer, T.
04f77381-d0ec-4cff-8581-4cf59184b3fd
Wiseman, P.
865f95f8-2200-46a8-bd5e-3ee30bb44072
Yates, R. M., Schady, P., Chen, T. W., Schweyer, T. and Wiseman, P.
(2020)
Present-day mass-metallicity relation for galaxies using a new electron temperature method.
Astronomy and Astrophysics, 634, [A107].
(doi:10.1051/0004-6361/201936506).
Abstract
Aims. We investigate electron temperature (Te) and gas-phase oxygen abundance (ZTe) measurements for galaxies in the local Universe (z < 0.25). Our sample comprises spectra from a total of 264 emission-line systems, ranging from individual HII regions to whole galaxies, including 23 composite HII regions from star-forming main sequence galaxies in the MaNGA survey. Methods. We utilise 130 of these systems with directly measurable Te(OII) to calibrate a new metallicity-dependent Te(OIII)-Te(OII) relation that provides a better representation of our varied dataset than existing relations from the literature. We also provide an alternative Te(OIII)-Te(NII) calibration. This new Te method is then used to obtain accurate ZTe estimates and form the mass - metallicity relation (MZR) for a sample of 118 local galaxies. Results. We find that all the Te(OIII)-Te(OII) relations considered here systematically under-estimate ZTe for low-ionisation systems by up to 0.6 dex. We determine that this is due to such systems having an intrinsically higher O+ abundance than O++ abundance, rendering ZTe estimates based only on [OIII] lines inaccurate. We therefore provide an empirical correction based on strong emission lines to account for this bias when using our new Te(OIII)-Te(OIII) and Te(OIII)-Te(NII) relations. This allows for accurate metallicities (1σ = 0.08 dex) to be derived for any low-redshift system with an [OIII]λ4363 detection, regardless of its physical size or ionisation state. The MZR formed from our dataset is in very good agreement with those formed from direct measurements of metal recombination lines and blue supergiant absorption lines, in contrast to most other Te-based and strong-line-based MZRs. Our new Te method therefore provides an accurate and precise way of obtaining ZTe for a large and diverse range of star-forming systems in the local Universe.
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Published date: 18 February 2020
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Acknowledgements. The authors would like to thank the anonymous referee for very helpful comments and suggestions, as well as Danielle Berg, Fabio Bresolin, I-Ting Ho, Rolf-Peter Kudritzki, Guinevere Kauffmann, Thomas Krühler, Brent Miszalski, Gwen Rudie, Alice Shapley, Martin Yates, and Jabran Zahid for valuable discussions during the undertaking of this work. We would also like to thank Ricardo Amorín, Fabio Bresolin, Alec Hirschauer, Janice Lee, Matt Nicholl, and John Salzer for providing additional data and guidance, and Christophe Morisset for help with running the pyneb package. This research was partly supported by the Munich Institute for Astro-and Particle Physics (MIAPP) of the DFG cluster of excellence “Origin and Structure of the Universe”. The authors would also like to acknowledge the TOPCAT interactive graphical viewer and editor (Taylor 2005) which was used for quick analysis and visualisation of our tabulated data. R. M. Y., T.-W. C., and P. W. acknowledge the support through the Sofia Kovalevskaja Award to P. Schady from the Alexander von Humboldt Foundation of Germany.
Publisher Copyright:
© R. M. Yates et al. 2020.
Keywords:
Galaxies: abundances, HII regions, ISM: abundances
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Local EPrints ID: 484095
URI: http://eprints.soton.ac.uk/id/eprint/484095
ISSN: 0004-6361
PURE UUID: 2ba417a9-c6cd-49b9-904d-7f96830959e0
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Date deposited: 09 Nov 2023 18:19
Last modified: 18 Mar 2024 03:43
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Author:
R. M. Yates
Author:
P. Schady
Author:
T. W. Chen
Author:
T. Schweyer
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