The dependence of oxygen and nitrogen abundances on stellar mass from the CALIFA survey



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Marino, Raffaella Anna and otros, ... (2016) The dependence of oxygen and nitrogen abundances on stellar mass from the CALIFA survey. Astronomy & Astrophysics, 595 . ISSN 1432-0746

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Context. The study of the integrated properties of star-forming galaxies is central to understand their formation and evolution. Some of these properties are extensive and therefore their analysis require totally covering and spatially resolved observations. Among these properties, metallicity can be defined in spiral discs by means of integral field spectroscopy (IFS) of individual H II regions. The simultaneous analysis of the abundances of primary elements, as oxygen, and secondary, as nitrogen, also provides clues about the star formation history and the processes that shape the build-up of spiral discs. Aims. Our main aim is to analyse simultaneously O/H and N/O abundance ratios in H II regions in different radial positions of the discs in a large sample of spiral galaxies to obtain the slopes and the characteristic abundance ratios that can be related to their integrated properties. Methods. We analysed the optical spectra of individual selected H II regions extracted from a sample of 350 spiral galaxies of the CALIFA survey. We calculated total O/H abundances and, for the first time, N/O ratios using the semi-empirical routine H II-C HI-MISTRY, which, according to Perez-Montero (2014, MNRAS, 441, 2663), is consistent with the direct method and reduces the uncertainty in the O/H derivation using [N II] lines owing to the dispersion in the O/H-N/O relation. Then we performed linear fittings to the abundances as a function of the de-projected galactocentric distances.
Results. The analysis of the radial distribution both for O/H and N/O in the non-interacting galaxies reveals that both average slopes are negative, but a non-negligible fraction of objects have a flat or even a positive gradient (at least 10% for O/H and 4% for N/O). The slopes normalised to the effective radius appear to have a slight dependence on the total stellar mass and the morphological type, as late low-mass objects tend to have flatter slopes. No clear relation is found, however, to explain the presence of inverted gradients in this sample, and there is no dependence between the average slopes and the presence of a bar. The relation between the resulting O/H and N/O linear fittings at the effective radius is much tighter (correlation coefficient ρ_s = 0.80) than between O/H and N/O slopes (ρ_s = 0.39) or for O/H and N/O in the individual H ii regions (ρ_s = 0.37). These O/H and N/O values at the effective radius also correlate very tightly (less than 0.03 dex of dispersion) with total luminosity and stellar mass. The relation with other integrated properties, such as star formation rate, colour, or morphology, can be understood only in light of the found relation with mass.

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© ESO 2016. Artículo firmado por 22 autores. This study makes uses of the data provided by the Calar Alto Legacy Integral Field Area (CALIFA) survey ( 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 at 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. E.P.M., J.M.V., C.K., S.P., and J.I.P. acknowledge support from the Spanish MICINN through grants AYA2010-21887-C04-01 and AYA2013-47742-C4-1-P and the Junta de Andalucía for grant EXC/2011 FQM-7058. R.G.B., R.G.D., and E.P. acknowledge support from grants AYA2014-57490-P and JA-FQM-2828. Support for L.G. is provided by the Ministry of Economy, Development, and Tourism's Millennium Science Initiative through grant IC120009, awarded to The Millennium Institute of Astrophysics, MAS. L.G. acknowledges support by CONICYT through FONDECYT grant 3140566. This research made use of python (, of Matplotlib (Hunter 2007), a suite of open-source python modules that provides a framework for creating scientific plots. We also thank Dr. Christophe Morisset for many discussions and constructive comments that have helped to improve the original manuscript.

Uncontrolled Keywords:Integral field spectroscopy; Star-forming galaxies; H-II regions; Potsdam multiaperture spectrophotometer; Active galactic nuclei; Gas-phase abundances; Digital sky survey; Metallicity relation; Spiral galaxies; Chemical abundances
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
ID Code:41023
Deposited On:07 Mar 2017 15:14
Last Modified:10 Dec 2018 15:04

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