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The O3N2 and N2 abundance indicators revisited: improved calibrations based on CALIFA and T_e-based literature data

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Marino, Raffaella Anna and Gil de Paz, Armando and Castillo Morales, África and otros, ... (2013) The O3N2 and N2 abundance indicators revisited: improved calibrations based on CALIFA and T_e-based literature data. Astronomy & Astrophysics, 559 . ISSN 0004-6361

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Official URL: http://dx.doi.org/10.1051/0004-6361/201321956




Abstract

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.


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© ESO, 2013. Artículo firmado por 33 autores. We would like to thank the anonymous referee for the review of our manuscript. The comments and suggestions helped to improve the content of the paper. R. A. Marino is funded by the Spanish program of International Campus of Excellence Moncloa (CEI). This study makes uses of the data provided by the Calar Alto Legacy Integral Field Area (CALIFA) survey (http://www.califa.caha.es). Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck-Institut fur Astronomie and the Instituto de Astrofísica de Andalucía (CSIC). CALIFA is the first legacy survey being performed at Calar Alto. The CALIFA collaboration would like to thank the IAA-CSIC and MPIA-MPG, as major partners of the observatory, and CAHA itself, for the unique access to telescope time and support in manpower and infrastructures. The CALIFA collaboration also thanks the CAHA staff for their dedication to this project. We thank the Viabilidad, Diseño, Acceso y Mejora funding program, ICTS-2009-10, for supporting the initial developement of this project. S.F.S., F.F.R.O., and D. Mast thank the Plan Nacional de Investigación y Desarrollo funding programs, AYA2012-31935 of the Spanish Ministerio de Economía y Competitividad, for the support given to this project. S. F. S thanks the the Ramón y Cajal project RyC-2011-07590 of the spanish Ministerio de Economía y Competitividad, for the support giving to this project. F. F. R. O. acknowledges the Mexican National Council for Science and Technology (CONACYT) for financial support under the program Estancias Postdoctorales y Sabáticas al Extranjero para la Consolidación de Grupos de Investigación, 2010-2012. We acknowledge financial support for the ESTALLIDOS collaboration by the Spanish Ministerio de Ciencia e Innovación under grant AYA2010-21887-C04-03. BG-L also acknowledges support from the Spanish Ministerio de Economía y Competitividad (MINECO) under grant AYA2012-39408-C02-02. J.F.-B. acknowledges financial support from the Ramón y Cajal Program and grant AYA2010-21322-C03-02 from the Spanish Ministry of Economy and Competitiveness (MINECO), as well as to the DAGAL network from the People's Program (Marie Curie Actions) of the European Union's Seventh Framework Program FP7/2007-2013/under REA grant agreement number PITN-GA-2011-289313. CK has been funded by project AYA2010-21887 from the Spanish PNAYA. P. acknowledges support by the Fundacao para a Ciencia e a Tecnologia (FCT) under project FCOMP-01-0124-FEDER-029170 (Reference FCT PTDC/FIS-AST/3214/2012), funded by FCT-MEC (PIDDAC) and FEDER (COMPETE). R. M. G. D. and R. G. B. also acknowledge support from the Spanish Ministerio de Economía y Competitividad (MINECO) under grant AyA2010-15081. V. S., L. G., and A. M. M. acknowledge financial support from the Fundacao para a Ciencia e a Tecnologia (FCT) under program Ciencia 2008 and the research grant PTDC/CTE-AST/112582/2009.

Uncontrolled Keywords:H-II regions; Star-forming galaxies; Integral field spectroscopy; Mass-metallicity relation; Digital sky survey; Potsdam multiaperture spectrophotometer; Localized chemical pollution; Ionized-gas; Oxygen abundances
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
ID Code:35020
Deposited On:14 Jan 2016 18:52
Last Modified:10 Dec 2018 15:05

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