Shape of the oxygen abundance profiles in CALIFA face-on spiral galaxies

¹ Instituto de Astrofísica de Andalucía (CSIC), Glorieta de la Astronomía s/n, Aptdo. 3004, 18080 Granada, Spain
e-mail: lsanchez@iaa.es
² Dpto. de Física Teórica y del Cosmos, Universidad de Granada, Facultad de Ciencias (Edificio Mecenas), 18071 Granada, Spain
³ Instituto de Astronomía, Universidad Nacional Autónoma de México, AP 70-264, 04510 México, D.F., Mexico
⁴ European Southern Observatory (ESO), Karl-Schwarzschild-Str. 2, 85748 Garching b. München, Germany
⁵ Instituto de Cosmologia, Relatividade e Astrofísica - ICRA, Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud 150, CEP 22290-180, Rio de Janeiro, RJ, Brazil
⁶ Observatorio Astronómico de Córdoba, Universidad Nacional de Córdoba, X 5000 BGR Cordoba, Argentina
⁷ Departamento de Física Teórica, Universidad Autónoma de Madrid, 28049 Cantoblanco, Spain
⁸ Astro-UAM, UAM, Unidad Asociada CSIC, Faculdad de Ciencias, Campus de Cantoblanco, 28049 Madrid, Spain
⁹ Sydney Institute for Astronomy, School of Physics A28, University of Sydney, NSW 2006, Australia
¹⁰ Instituto de Física e Química, Universidade Federal de Itajubá, Av. BPS, 1303, 37500-903 Itajubá-MG, Brazil
¹¹ Millennium Institute of Astrophysics MAS, Nuncio Monseñor Sótero Sanz 100, Providencia, 7500011 Santiago, Chile
¹² Departamento de Astronomía, Universidad de Chile, Camino El Observatorio 1515, Las Condes, Santiago, Chile
¹³ CEI Campus Moncloa, UCM-UPM, Departamento de Astrofísica y CC. de la Atmósfera, Facultad de CC. Físicas, Universidad Complutense de Madrid, Avda. Complutense s/n, 28040 Madrid, Spain
¹⁴ Department of Physics, Institute for Astronomy, ETH Zürich, 8093 Zürich, Switzerland
¹⁵ School of Physics and Astronomy, University of St Andrews, SUPA, North Haugh, KY16 9 SS St Andrews, UK
¹⁶ CIEMAT, Avda. Complutense 40, 28040 Madrid, Spain
¹⁷ Department of Physics, Chemistry and Biology, IFM, Linköping University, 581 83 Linköping, Sweden
¹⁸ Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany
¹⁹ Australian Astronomical Observatory, PO Box 915, North Ryde, NSW 1670, Australia
²⁰ Department of Physics and Astronomy, Macquarie University, NSW 2109, Australia

Received: 25 September 2015
Accepted: 12 December 2015

Abstract

We measured the gas abundance profiles in a sample of 122 face-on spiral galaxies observed by the CALIFA survey and included all spaxels whose line emission was consistent with star formation. This type of analysis allowed us to improve the statistics with respect to previous studies, and to properly estimate the oxygen distribution across the entire disc to a distance of up to 3−4 disc effective radii (r_e). We confirm the results obtained from classical H ii  region analysis. In addition to the general negative gradient, an outer flattening can be observed in the oxygen abundance radial profile. An inner drop is also found in some cases. There is a common abundance gradient between 0.5 and 2.0 r_e of α_{O / H} = − 0.075 dex /r_e with a scatter of σ = 0.016 dex /r_e when normalising the distances to the disc effective radius. By performing a set of Kolmogorov-Smirnov tests, we determined that this slope is independent of other galaxy properties, such as morphology, absolute magnitude, and the presence or absence of bars. In particular, barred galaxies do not seem to display shallower gradients, as predicted by numerical simulations. Interestingly, we find that most of thegalaxies in the sample with reliable oxygen abundance values beyond ~2 effective radii (57 galaxies) present a flattening of the abundance gradient in these outer regions. This flattening is not associated with any morphological feature, which suggests that it is a common property of disc galaxies. Finally, we detect a drop or truncation of the abundance in the inner regions of 27 galaxies in the sample; this is only visible for the most massive galaxies.