RESEARCH
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The Mass-Metallicity relation explored with CALIFA:
I. Is there a dependence on the star formation rate?

S. F. Sánchez, F. F. Rosales-Ortega, B. Jungwiert, J. Iglésias-Páramo, J. M. Vílchez, R. A. Marino, C. J. Walcher, B. Husemann, D. Mast, A. Monreal-Ibero, R. Cid Fernandes, E. Pérez, R. M. González Delgado, R. García-Benito, L. Galbany, G. van de Ven, K. Jahnke, H. Flores, J. Bland-Hawthorn, Á. R. López-Sánchez, V. Stanishev, D. Miralles-Caballero, A. I. Díaz, P. Sánchez-Blázquez, M. Mollá, A. Gallazzi, P. Papaderos, J. M. Gomes, N. Gruel, I. Pérez, T. Ruiz-Lara, E. Florido, A. de Lorenzo-Cáceres, J. Méndez-Abreu, C. Kehrig, M. M. Roth, B. Ziegler, J. Alves, L. Wisotzki, D. Kupko, A. Quirrenbach, D. J. Bomans

Abstract
We studied the global and local M-Z relation based on the first data available from the CALIFA survey (150 galaxies). This survey provides integral field spectroscopy of the complete optical extent of each galaxy (up to 2-3 effective radii), with enough resolution to separate individual HII regions and/or aggregations. Nearly ~3000 individual HII regions have been detected. The spectra cover the wavelength range between [OII]3727 and [SII]6731, with a sufficient signal-to-noise to derive the oxygen abundance and star-formation rate associated with each region. In addition, we have computed the integrated and spatially resolved stellar masses (and surface densities), based on SDSS photometric data. We explore the relations between the stellar mass, oxygen abundance and star-formation rate using this dataset.
We derive a tight relation between the integrated stellar mass and the gas-phase abundance, with a dispersion smaller than the one already reported in the literature (σΔlog(O/H) =0.07 dex). Indeed, this dispersion is only slightly larger than the typical error derived for our oxygen abundances. However, we do not find any secondary relation with the star-formation rate, other than the one induced due to the primary relation of this quantity with the stellar mass. The analysis for our sample of ~3000 individual HII regions confirm (i) the existence of a local mass-metallicity relation and (ii) the lack of a secondary relation with the star-formation rate. The same analysis is done for the specific star-formation rate, with similar results.
Our results agree with the scenario in which gas recycling in galaxies, both locally and globally, is much faster than other typical timescales, like that of gas accretion by inflow and/or metal loss due to outflows. In essence, late-type/disk dominated galaxies seem to be in a quasi-steady situation, with a behavior similar to the one expected from an instantaneous recycling/closed-box model.

Keywords
Galaxy: abundances – galaxies: ISM – galaxies: fundamental parameters – galaxies: spiral – galaxies: structure – galaxies: evolution

Notes
Table 1 and Appendix A are available in electronic form at http://www.aanda.org

Astronomy and Astrophysics
Volume 554, Number of pages A58_1
2013 June

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Instituto de Astrofísica e Ciências do Espaço Universidade do Porto Faculdade de Ciências da Universidade de Lisboa Fundação para a Ciência e a Tecnologia
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