Star-forming fractions and galaxy evolution with redshift in rich X-ray-selected galaxy clusters

Julie B. Nantais (1) , Alessandro Rettura (2) , Chris Lidman (3) , Ricardo Demarco (1) , Raphael Gobat (4) , Piero Rosati (5) , M. James Jee (6)

1 Universidad de Concepción - University of Concepcion [Chile]
2 Department of Astronomy [Pasadena]
3 Australian Astronomical Observatory
4 AIM (UMR7158 / UMR_E_9005 / UM_112) - Astrophysique Interprétation Modélisation
5 ESO - European Southern Observatory
6 Department of Physics, University of California

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.

Mots clés: galaxies: clusters: general; galaxies: evolution; galaxies: clusters: individual: RDCS J1252.9-2927; galaxies: clusters: individual: RX J0152.7-1357

Domaines: Astrophysique [astro-ph]

Julie B. Nantais, Alessandro Rettura, Chris Lidman, Ricardo Demarco, Raphael Gobat, et al.. Star-forming fractions and galaxy evolution with redshift in rich X-ray-selected galaxy clusters. Astronomy and Astrophysics - A&A, 2013, 556, pp.A112. ⟨10.1051/0004-6361/201321877⟩. ⟨cea-01135416⟩