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Outer-disk reddening and gas-phase metallicities: The CALIFA connection

Journal
Date Issued
2016
Author(s)
Marino, R. A.
•
Gil de Paz, A.
•
Sánchez, S. F.
•
Sánchez-Blázquez, P.
•
Cardiel, N.
•
Castillo-Morales, A.
•
Pascual, S.
•
Vílchez, J.
•
Kehrig, C.
•
Mollá, M.
•
Mendez-Abreu, J.
•
Catalán-Torrecilla, C.
•
Florido, E.
•
Perez, I.
•
Ruiz-Lara, T.
•
Ellis, S.
•
López-Sánchez, A. R.
•
González Delgado, R. M.
•
de Lorenzo-Cáceres, A.
•
García-Benito, R.
•
Galbany, L.
•
•
Cortijo, C.
•
Kalinova, V.
•
Mast, D.
•
Iglesias-Páramo, J.
•
Papaderos, P.
•
Walcher, C. J.
•
Bland-Hawthorn, J.
DOI
Abstract
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.
Volume
585
Start page
A47
Uri
Url
Issn Identifier
0004-6361
Ads BibCode
2016A&A...585A..47M
Rights
open.access
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