The O3N2 and N2 abundance indicators revisited: improved calibrations based on CALIFA and T e-based literature data
By R. Marino, F. Rosales-Ortega, S. Sánchez, A. Paz, J. Vílchez, D. Miralles-Caballero, C. Kehrig, E. P'erez-Montero, V. Stanishev, J. Iglesias-Páramo and 24 more. 2013
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The use of integral field spectroscopy is since recently allowing to measure the emission line fluxes of an increasingly large number of star-forming galaxies, both locally and at high redshift. Many studies have used these fluxes to derive the gas-phase metallicity of the galaxies by applying the so-called strong-line methods. However, the metallicity indicators that these datasets use were empirically calibrated using few direct abundance data points (T_e-based measurements). Furthermore, a precise determination of the prediction intervals of these indicators is commonly lacking in these calibrations. Such limitations might lead to systematic errors in determining the gas-phase metallicity, especially at high redshift, which might have a strong impact on our understanding of the chemical evolution of the Universe. The main goal of this study is to review the most widely used empirical oxygen calibrations, O3N2 and N2, by using new direct abundance measurements. We pay special attention to (1) the expected uncertainty of these calibrations as a function of the index value or abundance derived and (2) the presence of possible systematic offsets. This is possible thanks to the analysis of the most ambitious compilation of T_e-based H II regions to date. This new dataset compiles the Te-based abundances of 603 H II regions extracted from the literature but also includes new measurements from the CALIFA survey. Besides providing new and improved empirical calibrations for the gas abundance, we also present a comparison between our revisited calibrations with a total of 3423 additional CALIFA H II complexes with abundances derived using the ONS calibration from the literature. The combined analysis of T_e-based and ONS abundances allows us to derive their most accurate calibration to date for both the O3N2 and N2 single-ratio indicators, in terms of all statistical significance, quality, and coverage of the parameters space. In particular, we infer that these indicators show shallower abundance dependencies and statistically significant offsets compared to others'. The O3N2 and N2 indicators can be empirically applied to derive oxygen abundances calibrations from either direct abundance determinations with random errors of 0.18 and 0.16, respectively, or from indirect ones (but based on a large amount of data), reaching an average precision of 0.08 and 0.09 dex (random) and 0.02 and 0.08 dex (systematic; compared to the direct estimations), respectively.
Subfields: Astronomy and Astrophysics
View Paper: https://www.semanticscholar.org/paper/ef41de796e5635c4bfb72af1d14e8587b1eac00a
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In Astronomy and Astrophysics
Citations in the corpus
- Chemical abundances in high-redshift galaxies: a powerful new emission line diagnostic (2016, background): “…diagnostics are either based on samples of local H II regions (Denicoló et al. 2002; Pettini & Pagel 2004; Pérez-Montero et al 2009), local galaxies (Marino et al. 2013; Morales-Luis et al. 2014), or photoionization models based on local galaxy conditions (Kewley & Dopita 2002; Blanc et al. 2015).”
- A characteristic oxygen abundance gradient in galaxy disks unveiled with CALIFA (2013, methodology): “We adopted the functional form and calibration by Pettini & Pagel (2004), although its correspondence with temperature-anchored abundances at the high-metallicity range is still under debate (Marino et al. 2013).”
- New fully empirical calibrations of strong-line metallicity indicators in star forming galaxies (2016, methodology): “…in which metallicity have been previously derived with the Te method (e.g. Pettini & Pagel 2004; Pilyugin & Thuan 2005; Pilyugin et al. 2010b, 2012; Marino et al. 2013; Pilyugin & Grebel 2016), or theoretically, in which oxygen abundance have been inferred via photoionization models (e.g. McGaugh…”
- New calibrations for abundance determinations in H ii regions (2016, methodology): “On the other hand, asample of Hii regions in which the oxygen abundances are determined through the directTe method can serve as basis of a calibration (e.g.,Pilyugin 2000, 2001a; Pilyugin et al. 2010; Marino et al. 2013).”
- Deriving model-based Te-consistent chemical abundances in ionized gaseous nebulae (2014, methodology): “For this purpose profiting the compilation made by Marino et al. (2013) of H ii regions and star-for galaxies with auroral emission-lines, their oxygen and nitrogen abundances were recalculated using the software pyneb (Luridiana et al. 2012).”
- PyNeb: a new tool for analyzing emission lines - I. Code description and validation of results (2014, neutral): “…used in a number of papers (GarcíaRojas et al. 2012, 2013, 2014; Esteban et al. 2013, 2014; Kameswara Rao et al. 2013; Nicholls et al. 2013, 2014; Marino et al. 2013; Delgado-Inglada et al. 2014; Delgado-Inglada & Rodríguez 2014; Mesa-Delgado et al. 2014; Sankrit et al. 2014; Ho et al. 2014;…”