1. SHARDS: stellar populations and star formation histories of a mass-selected sample of 0.65 \textless z \textless 1.1 galaxies
- Author
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Hernan-Caballero, Antonio, Alonso-Herrero, Almudena, Perez-Gonzalez, Pablo G., Cardiel, Nicolas, Cava, Antonio, Ferreras, Ignacio, Barro, Guillermo, Tresse, Laurence, Daddi, Emanuele, Cenarro, Javier, Conselice, Christopher J., Guzman, Rafael, Gallego, Jesus, Laboratoire d'Astrophysique de Marseille (LAM), and Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph] - Abstract
International audience; We report on results from the analysis of a stellar mass-selected (log (M-*/M-circle dot) \textgreater= 9.0) sample of 1644 galaxies at 0.65 \textless z \textless 1.1 with ultradeep (m(AB) \textless 26.5) optical medium-band (R similar to 50) photometry from the Survey for High-z Absorption Red and Dead Sources (SHARDS). The spectral resolution of SHARDS allows us to consistently measure the strength of the 4000 A spectral break [D-n(4000), an excellent age indicator for the stellar populations of quiescent galaxies] for all galaxies at z similar to 0.9 down to log (M-*/M-circle dot) similar to 9. The D-n(4000) index cannot be resolved from broad-band photometry, and measurements from optical spectroscopic surveys are typically limited to galaxies at least 10 times more massive. When combined with the rest-frame U - V colour, (U - V)(r), D-n(4000) provides a powerful diagnostic of the extinction affecting the stellar population that is relatively insensitive to degeneracies with age, metallicity or star formation history. We use this novel approach to estimate de-reddened colours and light-weighted stellar ages for individual sources. We explore the relationships linking stellar mass, (U - V)(r), and D-n(4000) for the sources in the sample, and compare them to those found in local galaxies. The main results are: (a) both D-n(4000) and (U - V)(r) correlate with M-*. The dispersion in D-n(4000) values at a given M-* increases with M-*, while the dispersion for (U - V)(r) decreases due to the higher average extinction prevalent in massive star-forming galaxies. (b) For massive galaxies, we find a smooth transition between the blue cloud and red sequence in the intrinsic U - V colour, in contrast with other recent results. (c) At a fixed stellar age, we find a positive correlation between extinction and stellar mass. (d) The fraction of sources with declining or halted star formation increases steeply with the stellar mass, from similar to 5 per cent at log (M-*/M-circle dot) = 9.0-9.5 to similar to 80 per cent at log (M-*/M-circle dot) \textgreater 11, in agreement with downsizing scenarios.
- Published
- 2013