TY - JOUR
T1 - Outer-disk reddening and gas-phase metallicities
T2 - The CALIFA connection
AU - Marino, R. A.
AU - Gil De Paz, A.
AU - Sánchez, S. F.
AU - Sánchez-Blázquez, P.
AU - Cardiel, N.
AU - Castillo-Morales, A.
AU - Pascual, S.
AU - Vílchez, J.
AU - Kehrig, C.
AU - Mollá, M.
AU - Mendez-Abreu, J.
AU - Catalán-Torrecilla, C.
AU - Florido, E.
AU - Perez, I.
AU - Ruiz-Lara, T.
AU - Ellis, S.
AU - López-Sánchez, A. R.
AU - González Delgado, R. M.
AU - De Lorenzo-Cáceres, A.
AU - García-Benito, R.
AU - Galbany, L.
AU - Zibetti, S.
AU - Cortijo, C.
AU - Kalinova, V.
AU - Mast, D.
AU - Iglesias-Páramo, J.
AU - Papaderos, P.
AU - Walcher, C. J.
AU - Bland-Hawthorn, J.
AU - Team, Califa
PY - 2016/1/1
Y1 - 2016/1/1
N2 - 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-gas oxygen 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 ∼ 0.5mag 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.
AB - 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-gas oxygen 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 ∼ 0.5mag 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.
KW - Galaxies: abundances
KW - Galaxies: evolution
KW - Galaxies: ISM
KW - Galaxies: photometry
KW - Hii regions
KW - ISM: abundances
UR - https://www.scopus.com/pages/publications/84951781079
U2 - 10.1051/0004-6361/201526986
DO - 10.1051/0004-6361/201526986
M3 - Article
AN - SCOPUS:84951781079
SN - 0004-6361
VL - 585
SP - 1
EP - 29
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
M1 - A47
ER -