Volume 491, Number 3, December I 2008
|Page(s)||713 - 730|
|Published online||15 October 2008|
The VVDS-SWIRE-GALEX-CFHTLS surveys: physical properties of galaxies at z below 1.2 from photometric data *
Institut d'Astrophysique de Paris, CNRS, Université Pierre & Marie Curie, UMR 7095, 98 bis Boulevard Arago, 75014 Paris, France e-mail: firstname.lastname@example.org
2 Laboratoire d'Astrophysique de Marseille (UMR6110), CNRS-Université de Provence, 38 rue Frederic Joliot-Curie, 13388 Marseille Cedex 13, France
3 INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, 40127, Bologna, Italy
4 Laboratoire d'Astrophysique de Toulouse-Tarbes, Université de Toulouse, CNRS, 14 avenue Edouard Belin, 31400 Toulouse, France
5 IASF-INAF, via Bassini 15, 20133, Milano, Italy
6 Canada France Hawaii Telescope corporation, Mamalahoa Hwy, Kamuela, HI-96743, USA
7 Centro de Astrofísica da Universidade do Porto, Rua das Estrelas, 4150-762, Porto, Portugal
8 Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
9 IRA-INAF, via Gobetti 101, 40129, Bologna, Italy
10 INAF-Osservatorio Astronomico di Roma, via di Frascati 33, 00040, Monte Porzio Catone, Italy
11 School of Physics & Astronomy, University of Nottingham, University Park, Nottingham, NG72RD, UK
12 Astrophysical Institute Potsdam, An der Sternwarte 16, 14482, Potsdam, Germany
13 INAF-Osservatorio Astronomico di Brera, via Brera 28, 20021, Milan, Italy
14 Institute for Astronomy, 2680 Woodlawn Dr., University of Hawaii, Honolulu, Hawaii, 96822, USA
15 Observatoire de Paris, LERMA, 61 Avenue de l'Observatoire, 75014, Paris, France
16 Università di Bologna, Dipartimento di Astronomia, via Ranzani 1, 40127, Bologna, Italy
17 Centre de Physique Théorique, UMR 6207 CNRS-Université de Provence, 13288 Marseille, France
18 Max-Planck-Institut fur Extraterrestrische Physik, Giessenbachstrasse, 85748 Garching b. Muenchen, Germany
19 Universitats-Sternwarte, Scheinerstrasse 1, 81679 Muenchen, Germany
20 Integral Science Data Centre, ch. d'Écogia 16, 1290, Versoix, Switzerland
21 Geneva Observatory, ch. des Maillettes 51, 1290, Sauverny, Switzerland
22 The Andrzej Soltan Institute for Nuclear Studies, ul. Hoza 69, 00-681 Warszawa, Poland
23 INAF-Osservatorio Astronomico di Capodimonte, via Moiariello 16, 80131, Napoli, Italy
24 University of California, San Diego 9500 Gilman Dr. La Jolla, CA 92093-0424, USA
25 California Institute of Technology, MC 405-47, 1200 East California Boulevard, Pasadena, CA 91125, USA
Accepted: 11 September 2008
Measuring the build-up of stellar mass is one of the main objectives of studies of galaxy evolution. Traditionally, the mass in stars and the star formation rates have been measured by different indicators, such as photometric colours, emission lines, and the UV and IR emission. We intend to show that it is possible to derive the physical parameters of galaxies from their broad-band spectral energy distribution out to a redshift of 1.2. This method has the potential to yield the physical parameters of all galaxies in a single field in a homogeneous way, thus overcoming problems with the sample size that particularly plague methods relying on spectroscopy. We use an extensive dataset, assembled in the context of the VVDS survey, which reaches from the UV to the IR and covers a sample of 84 073 galaxies over an area of 0.89 deg2. We also use a library of 100 000 model galaxies with a wide variety of star formation histories (in particular including late bursts of star formation). We find that we can determine the physical parameters stellar mass, age, and star formation rate with good confidence. We validate the star formation rate determination in particular by comparing it to a sample of spectroscopically observed galaxies with an emission-line measurement. While the attenuation in the galaxies shows more scatter, the mean over the sample is unbiased. Metallicity, however, cannot be measured from rest-frame optical photometry alone. As a first application we use our sample to build the number density function of galaxies as a function of stellar mass, specific star formation rate, and redshift. We are then able to study whether the stellar mass function at a later time can be predicted from the stellar mass function and star formation rate distribution at an earlier time. We find that, between redshifts of 1.02 and 0.47, the predicted growth in stellar mass from star formation agrees with the observed one. However, the predicted stellar mass density for massive galaxies is lower than observed, while the mass density of intermediate mass galaxies is overpredicted. This apparent discrepancy can be explained by major and minor mergers. Indeed, when comparing with a direct measurement of the major merger rate from the VVDS survey, we find that major mergers can account for about half of the mass build-up at the massive end. Minor mergers are very likely to contribute the missing fraction.
Key words: surveys / galaxies: evolution / galaxies: photometry / galaxies: general
Based on data obtained with the European southern observatory Very Large Telescope, Paranal, Chile, programme 070A-9007(A) and on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council (NRC) of Canada, the Institut National des Science de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at TERAPIX and the Canadian Astronomy Data Centre as part of the Canada-France-Hawaii Telescope Legacy Survey, a collaborative project of NRC and CNRS.
© ESO, 2008
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