Volume 609, January 2018
|Number of page(s)||47|
|Published online||02 February 2018|
The shape of oxygen abundance profiles explored with MUSE: evidence for widespread deviations from single gradients
1 Instituto de Astrofísica de Andalucía (CSIC), Glorieta de la Astronomía s/n, Aptdo. 3004, 18080 Granada, Spain
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.
4 Instituto Carlos I de Física Teórica y computacional, Universidad de Granada, 18071 Granada, Spain
5 Instituto de Astrofísica de Canarias, Calle Vía Láctea s/n, 38205 La Laguna, Tenerife, Spain
6 Universidad de La Laguna, Dpto. Astrofísica, 38206 La Laguna, Tenerife, Spain
7 PITT PACC, Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA
8 European Southern Observatory, Alonso de Córdova 3107, Casilla 19001, Santiago, Chile
9 Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße, 85748 Garching, Germany
10 Finnish Centre for Astronomy with ESO (FINCA), University of Turku, Vaisalantie 20, 21500 Piikkio, Finland
11 Tuorla Observatory, Department of Physics and Astronomy, University of Turku, Vaisalantie 20, 21500 Piikkio, Finland
12 Department of Physics, University of Warwick, Coventry CV4 7AL, UK
Received: 1 July 2017
Accepted: 2 October 2017
We characterised the oxygen abundance radial distribution of a sample of 102 spiral galaxies observed with VLT/MUSE using the O3N2 calibrator. The high spatial resolution of the data allowed us to detect 14345 H ii regions with the same image quality as with photometric data, avoiding any dilution effect. We developed a new methodology to automatically fit the abundance radial profiles, finding that 55 galaxies of the sample exhibit a single negative gradient. The remaining 47 galaxies also display, as well as this negative trend, either an inner drop in the abundances (21), an outer flattening (10), or both (16), which suggests that these features are a common property of disc galaxies. The presence and depth of the inner drop depends on the stellar mass of the galaxies with the most massive systems presenting the deepest abundance drops, while there is no such dependence in the case of the outer flattening. We find that the inner drop appears always around 0.5 re, while the position of the outer flattening varies over a wide range of galactocentric distances. Regarding the main negative gradient, we find a characteristic slope in the sample of αO/H =−0.10 ± 0.03 dex /re. This slope is independent of the presence of bars and the density of the environment. However, when inner drops or outer flattenings are detected, slightly steeper gradients are observed. This suggests that radial motions might play an important role in shaping the abundance profiles. We define a new normalisation scale (“the abundance scale length”, rO/H) for the radial profiles based on the characteristic abundance gradient, with which all the galaxies show a similar position for the inner drop (~0.5 rO/H) and the outer flattening (~1.5 rO/H). Finally, we find no significant dependence of the dispersion around the negative gradient with any property of the galaxies, with values compatible with the uncertainties associated with the derivation of the abundances.
Key words: galaxies: abundances / galaxies: evolution / galaxies: ISM / galaxies: spiral / techniques: imaging spectroscopy / techniques: spectroscopic
© ESO, 2018
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