Issue |
A&A
Volume 581, September 2015
|
|
---|---|---|
Article Number | A103 | |
Number of page(s) | 44 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361/201525938 | |
Published online | 15 September 2015 |
The CALIFA survey across the Hubble sequence
Spatially resolved stellar population properties in galaxies⋆
1
Instituto de Astrofísica de Andalucía (CSIC),
PO Box 3004,
18080
Granada,
Spain
e-mail:
rosa@iaa.es
2
Departamento de Física, Universidade Federal de Santa
Catarina, PO Box 476,
88040-900
Florianópolis, SC, Brazil
3
Instituto de Astronomía, Universidad Nacional Autonóma de
Mexico, A.P.
70-264, 04510
México,
Mexico
4
Departamento de Investigación Básica, CIEMAT, Avda. Complutense 40, 28040
Madrid,
Spain
5
Departamento de Física Teórica y del Cosmos, University of
Granada, Facultad de Ciencias (Edificio Mecenas), 18071
Granada,
Spain
6
Depto. de Física Teórica, Universidad Autónoma de
Madrid, 28049
Madrid,
Spain
7
Leibniz-Institut für Astrophysik Potsdam (AIP),
An der Sternwarte 16,
14482
Potsdam,
Germany
8
University of Vienna, Türkenschanzstrasse 17, 1180
Vienna,
Austria
9
Instituto de Astrofísica de Canarias (IAC),
38205, La Laguna, Tenerife, Spain
10
Sydney Institute for Astronomy, The University of
Sydney, NSW 2006,
Australia
11
Millennium Institute of Astrophysics and Departamento de
Astronomía, Universidad de Chile, Casilla 36-D, 1058
Santiago,
Chile
12
Departamento de Astronomía, Universidad de Chile,
Casilla 36-D, 1058
Santiago,
Chile
13
INAF − Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi
5, 50125
Firenze,
Italy
14
European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748
Garching b. München,
Germany
15
Estación Experimental de Zonas Aridas (CSIC), Ctra. de Sacramento
s/n, La Cañada, 04120
Almería,
Spain
16
Department of Physics 4-181 CCIS, University of
Alberta, Edmonton AB
T6G 2E1,
Canada
17
Australian Astronomical Observatory, PO BOX 296, Epping, 1710
NSW,
Australia
18
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
19
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
20
School of Physics and Astronomy, University of St.
Andrews, North Haugh, St. Andrews,
KY169 SS,
UK
21
Landessternwarte, Zentrum fur Astronomie der Universitat
Heidelberg, Königstuhl
12, 69117
Heidelberg,
Germany
Received: 21 February 2015
Accepted: 11 June 2015
Various different physical processes contribute to the star formation and stellar mass assembly histories of galaxies. One important approach to understanding the significance of these different processes on galaxy evolution is the study of the stellar population content of today’s galaxies in a spatially resolved manner. The aim of this paper is to characterize in detail the radial structure of stellar population properties of galaxies in the nearby universe, based on a uniquely large galaxy sample, considering the quality and coverage of the data. The sample under study was drawn from the CALIFA survey and contains 300 galaxies observed with integral field spectroscopy. These cover a wide range of Hubble types, from spheroids to spiral galaxies, while stellar masses range from M⋆ ~ 109 to 7 × 1011 M⊙. We apply the fossil record method based on spectral synthesis techniques to recover the following physical properties for each spatial resolution element in our target galaxies: the stellar mass surface density (μ⋆), stellar extinction (AV), light-weighted and mass-weighted ages (⟨log age⟩L, ⟨log age⟩M), and mass-weighted metallicity (⟨log Z⋆⟩M). To study mean trends with overall galaxy properties, the individual radial profiles are stacked in seven bins of galaxy morphology (E, S0, Sa, Sb, Sbc, Sc, and Sd). We confirm that more massive galaxies are more compact, older, moremetal rich, and less reddened by dust. Additionally, we find that these trends are preserved spatially with the radial distance to the nucleus. Deviations from these relations appear correlated with Hubble type: earlier types are more compact, older, and more metal rich for a given M⋆, which is evidence that quenching is related to morphology, but not driven by mass. Negative gradients of ⟨log age⟩L are consistent with an inside-out growth of galaxies, with the largest ⟨log age⟩L gradients in Sb–Sbc galaxies. Further, the mean stellar ages of disks and bulges are correlated and with disks covering a wider range of ages, and late-type spirals hosting younger disks. However, age gradients are only mildly negative or flat beyond R ~ 2 HLR (half light radius), indicating that star formation is more uniformly distributed or that stellar migration is important at these distances. The gradients in stellar mass surface density depend mostly on stellar mass, in the sense that more massive galaxies are more centrally concentrated. Whatever sets the concentration indices of galaxies obviously depends less on quenching/morphology than on the depth of the potential well. There is a secondary correlation in the sense that at the same M⋆ early-type galaxies have steeper gradients. The μ⋆ gradients outside 1 HLR show no dependence on Hubble type. We find mildly negative ⟨log Z⋆⟩M gradients, which are shallower than predicted from models of galaxy evolution in isolation. In general, metallicity gradients depend on stellar mass, and less on morphology, hinting that metallicity is affected by both – the depth of the potential well and morphology/quenching. Thus, the largest ⟨log Z⋆⟩M gradients occur in Milky Way-like Sb–Sbc galaxies, and are similar to those measured above the Galactic disk. Sc spirals show flatter ⟨log Z⋆⟩M gradients, possibly indicating a larger contribution from secular evolution in disks. The galaxies from the sample have decreasing-outward stellar extinction; all spirals show similar radial profiles, independent from the stellar mass, but redder than E and S0. Overall, we conclude that quenching processes act in manners that are independent of mass, while metallicity and galaxy structure are influenced by mass-dependent processes.
Key words: techniques: spectroscopic / Galaxy: evolution / Galaxy: stellar content / galaxies: structure / Galaxy: fundamental parameters / galaxies: spiral
© ESO, 2015
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