Volume 556, August 2013
|Number of page(s)||17|
|Published online||06 August 2013|
Star-forming fractions and galaxy evolution with redshift in rich X-ray-selected galaxy clusters⋆
1 Departamento de AstronomíaUniversidad de Concepción, Casilla 160-C, Concepcion, Chile
2 Department of Astronomy, California Institute of Technology, MS 105-24, Pasadena, CA 91125, USA
3 Australian Astronomical Observatory, PO Box 296, Epping NSW 1710, Australia
4 Laboratoire AIM-Paris-Saclay, CEA/DSM-CNRS-Université Paris Diderot, Irfu/Service d’Astrophysique, CEA Saclay, Orme des Merisiers, 91191 Gif-sur-Yvette, France
5 ESO, Karl-Schwarzchild Strasse 2, 85748 Garching, Germany
6 Department of Physics, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
Received: 10 May 2013
Accepted: 12 June 2013
We have compared stacked spectra of galaxies, grouped by environment and stellar mass, among 58 members of the redshift z = 1.24 galaxy cluster RDCS J1252.9-2927 (J1252.9) and 134 galaxies in the z = 0.84 cluster RX J0152.7-1357 (J0152.7). These two clusters are excellent laboratories to study how galaxies evolve from star-forming to passive at z ~ 1. We measured spectral indices and star-forming fractions for our density- and mass-based stacked spectra. The star-forming fraction among low-mass galaxies (<7 × 1010M⊙) is higher in J1252.9 than in J0152.7, at about 4σ significance. Thus star formation is being quenched between z = 1.24 and z = 0.84 for a substantial fraction of low-mass galaxies. Star-forming fractions were also found to be higher in J1252.9 in all environments, including the core. Passive galaxies in J1252.9 have systematically lower Dn4000 values than in J0152.7 in all density and mass groups, consistent with passive evolution at modestly super-solar metallicities.
Key words: galaxies: clusters: individual: RX J0152.7-1357 / galaxies: clusters: individual: RDCS J1252.9-2927 / galaxies: evolution / galaxies: clusters: general
Table 1 is only available in electronic form at http://www.aanda.org
© ESO, 2013
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