Issue |
A&A
Volume 585, January 2016
|
|
---|---|---|
Article Number | A47 | |
Number of page(s) | 29 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361/201526986 | |
Published online | 16 December 2015 |
Outer-disk reddening and gas-phase metallicities: The CALIFA connection
1
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
e-mail:
ramarino@ucm.es
2
Department of Physics, Institute for Astronomy,
ETH Zürich, 8093
Zürich,
Switzerland
3
Departamento de Astrofísica y CC. de la Atmósfera, Facultad de CC.
Físicas, Universidad Complutense de Madrid, Avda. Complutense s/n, 28040
Madrid,
Spain
4 Instituto de Astronomía, Universidad Nacional Autonóma de
México, A.P. 70-264, 04510 México, D. F., Mexico
5
Departamento de Física Teórica, Universidad Autónoma de
Madrid, 28049
Madrid,
Spain
6
Instituto de Física de Cantabria (CSIC -Universidad de
Cantabria), Avenida de los Castros
s/n, 39005
Santander,
Spain
7
CIEMAT, Departamento de Investigación Básica,
Avda. Complutense 40,
28040
Madrid,
Spain
8 School of Physics and Astronomy, University of St Andrews,
North Haugh, St. Andrews, KY16 9SS, UK ( SUPA )
9
Instituto Universitario Carlos I de Física Teórica y
Computacional, Universidad de Granada, 18071
Granada,
Spain
10
Departamento de Física Teórica y del Cosmos, Facultad de Ciencias,
Universidad de Granada, 18071
Granada,
Spain
11
Instituto de Astrofísica de Andalucía (IAA/CSIC ),
Glorieta de la Astronomía s/n Aptdo.
3004, 18080
Granada,
Spain
12
Australian Astronomical Observatory, PO Box 915, North Ryde, NSW
1670,
Australia
13 Department of Physics and Astronomy, Macquarie University,
NSW 2109, Australia
14
Millennium Institute of Astrophysics MAS,
Nuncio Monseñor Sótero Sanz 100, Providencia,
7500011
Santiago,
Chile
15
Departamento de Astronomía, Universidad de Chile, Camino El
Observatorio 1515, Las
Condes, Santiago,
Chile
16
INAF–Osservatorio Astrofisico di Arcetri – Largo Enrico Fermi,
5 50125
Firenze,
Italy
17
Department of Physics 4-181 CCIS, University of
Alberta, Edmonton AB
T6G 2E1,
Canada
18
Instituto de Cosmologia, Relatividade e Astrofísica, Centro Brasileiro de Pesquisas
Físicas,
CEP 22290-180
Rio de Janeiro,
Brazil
19
Estación Experimental de Zonas Aridas (CSIC), Carretera de
Sacramento s/n, La Cañada, 04120
Almería,
Spain
20
Instituto de Astrofísica e Ciências do Espaço, Universidade do
Porto, 4150-762
Porto,
Portugal
21
Centro de Astrofísica da Universidade do Porto,
Rua das Estrelas, 4150-762
Porto,
Portugal
22
Leibniz-Institut für Astrophysik Potsdam (AIP),
An der Sternwarte 16,
14482
Potsdam,
Germany
23 Sydney Institute for Astronomy, School of Physics A28,
University of Sydney, NSW2006, Australia
Received: 17 July 2015
Accepted: 10 September 2015
We study, for the first time in a statistically significant and well-defined sample, the relation between the outer-disk ionized-gas metallicity gradients and the presence of breaks in the surface brightness profiles of disk galaxies. Sloan Digital Sky Survey (SDSS) g′- and r′-band surface brightness, (g′ – r′) color, and ionized-gasoxygen abundance profiles for 324 galaxies within the Calar Alto Legacy Integral Field Area (CALIFA) survey are used for this purpose. We perform a detailed light-profile classification, finding that 84% of our disks show down- or up-bending profiles (Type II and Type III, respectively), while the remaining 16% are well fitted by one single exponential (Type I). The analysis of the color gradients at both sides of this break shows a U-shaped profile for most Type II galaxies with an average minimum (g′ − r′) color of ~0.5 mag and an ionized-gas metallicity flattening associated with it only in the case of low-mass galaxies. Comparatively, more massive systems show a rather uniform negative metallicity gradient. The correlation between metallicity flattening and stellar mass for these systems results in p-values as low as 0.01. Independent of the mechanism having shaped the outer light profiles of these galaxies, stellar migration or a previous episode of star formation in a shrinking star-forming disk, it is clear that the imprint in their ionized-gas metallicity was different for low- and high-mass Type II galaxies. In the case of Type III disks, a positive correlation between the change in color and abundance gradient is found (the null hypothesis is ruled out with a p-value of 0.02), with the outer disks of Type III galaxies with masses ≤1010 M⊙ showing a weak color reddening or even a bluing. This is interpreted as primarily due to a mass downsizing effect on the population of Type III galaxies that recently experienced an enhanced inside-out growth.
Key words: galaxies: abundances / galaxies: evolution / galaxies: photometry / galaxies: ISM / ISM: abundances / Hii regions
© ESO, 2015
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