A novel approach to correcting $T_e$-based mass-metallicity relations

Abstract

Deriving oxygen abundances from the electron temperature (hereafter the $T_e$-method) is the gold-standard for extragalactic metallicity studies. However, unresolved temperature fluctuations within individual HII regions and across different HII regions throughout a galaxy can bias metallicity estimates low, with a magnitude that depends on the underlying and typically unknown temperature distribution. Using a toy model, we confirm that computing $T_e$-based metallicities using the temperature derived from the [O III] $\lambda$4363/$\lambda$5007 or [O II] $\lambda \lambda$7320,7330 / [O II] $\lambda \lambda$3727 ratio ('ratio temperature'; $T_{\mathrm{ratio}}$) results in an underprediction of metallicity when temperature fluctuations are present. In contrast, using the unobservable 'line temperatures' ($T_{\mathrm{line}}$) that provide the mean electron and ion density-weighted emissivity yield an accurate metallicity estimate. To correct this bias in low-mass galaxies, we demonstrate an example calibration of a relation between T_ratio and T_line based on a high-resolution (4.5 pc) RAMSES-RTZ simulation of a dwarf galaxy that self-consistently models the formation of multiple HII regions and ion temperature distribution in a galactic context. Applying this correction to the low-mass end of the mass-metallicity relation shifts its normalization up by 0.18 dex on average and flattens its slope from 0.87 to 0.58, highlighting the need for future studies to account for, and correct, this bias.

arXiv comment6 pages, 6 figures, accepted for publication in MNRAS

References in corpus (33)

• The Origin of the Mass--Metallicity Relation: Insights from 53,000 Star-Forming Galaxies in the SDSS
• Metallicity Calibrations and the Mass-Metallicity Relation for Star-Forming Galaxies
• Radiative transfer in a clumpy universe: IV. New synthesis models of the cosmic UV/X-ray background
• A fundamental relation between mass, SFR and metallicity in local and high redshift galaxies
• PyNeb: a new tool for analyzing emission lines. I. Code description and validation of results
• The Mass-Metallicity Relation with the Direct Method on Stacked Spectra of SDSS Galaxies
• Understanding Galaxy Evolution through Emission Lines
• The Origin and Evolution of the Galaxy Mass-Metallicity Relation
• The Mass-Metallicity and the Fundamental Metallicity Relation revisited on a fully Te-based abundance scale for galaxies
• On Measuring Chemical Abundances in Distant Galaxies Using Global Emission Line Spectra
• Clues to the Origin of the Mass-Metallicity Relation: Dependence on Star Formation Rate and Galaxy Size
• New fully empirical calibrations of strong-line metallicity indicators in star forming galaxies
• The chemical enrichment in the early Universe as probed by JWST via direct metallicity measurements at z~8
• CHIANTI - an atomic database for emission lines - Paper XV: Version 9, improvements for the X-ray satellite lines
• The evolution of the mass-metallicity relation in IllustrisTNG
• Feedback-regulated star formation and escape of LyC photons from mini-haloes during reionisation
• A fundamental relation between the metallicity, gas content, and stellar mass of local galaxies
• The Formation of Dust Lanes: Implications for Galaxy Evolution
• On the abundance discrepancy problem in HII regions
• Biases in abundance derivations for metal-rich nebulae
• Galaxy metallicity scaling relations in the EAGLE simulations
• Ionized gaseous nebulae chemical abundance determination using the direct method
• Collision Strengths for [O III] Optical and Infrared Lines
• Optical Recombination Lines of Heavy-elements in Giant Extragalactic HII Regions
• First Insights into the ISM at $z>8$ with JWST: Possible Physical Implications of a High [O III]$\lambda 4363$/[O III]$\lambda 5007$
• Present-day mass-metallicity relation for galaxies using a new electron-temperature method
• Abundance determination from global emission-line SDSS spectra: exploring objects with high N/O ratios
• Improved collision strengths and line ratios for forbidden [O III] far-infrared and optical lines
• Low-redshift lowest-metallicity star-forming galaxies in the SDSS DR14
• RAMSES-RTZ: Non-Equilibrium Metal Chemistry and Cooling Coupled to On-The-Fly Radiation Hydrodynamics
• The AGORA High-resolution Galaxy Simulations Comparison Project. III: Cosmological zoom-in simulation of a Milky Way-mass halo
• A Preview of JWST Metallicity Studies at Cosmic Noon: The First Detection of Auroral [O II] Emission at High Redshift
• MgII in the JWST Era: a Probe of Lyman Continuum Escape?

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