The zCOSMOS survey: the role of the environment in the evolution of the luminosity function of different galaxy types

E. Zucca (1) , S. Bardelli (2) , M. Bolzonella (3) , G. Zamorani (4) , O. Ilbert (5) , L. Pozzetti (2) , M. Mignoli (4) , K. Kovac (4) , S. Lilly (4) , L. Tresse (5) , L. Tasca (5) , P. Cassata (4) , C. Halliday , D. Vergani (6) , K. Caputi (4) , C. M. Carollo (7) , T. Contini (8) , J. P. Kneib (8) , O. Lefevre (5) , V. Mainieri (4) , A. Renzini (4) , M. Scodeggio (9) , A. Bongiorno (3) , G. Coppa (4) , O. Cucciati (10) , S. Delatorre , L. Deravel , P. Franzetti (4) , B. Garilli (4) , A. Iovino (4) , P. Kampczyk (4) , C. Knobel (4) , F. Lamareille (8) , J. F. Leborgne (8) , V. Lebrun (5) , C. Maier (4) , R. Pello' , Y. Peng (11) , E. Perez-Montero (8) , E. Ricciardelli (4) , J. D. Silverman (4) , M. Tanaka (12) , U. Abbas (4) , D. Bottini (4) , A. Cappi (13) , Alessandro Cimatti (4) , L. Guzzo (4) , A. M. Koekemoer (14) , A. Leauthaud (5) , D. Maccagni (4) , Christian Marinoni (15, 16) , H. J. Mccracken (17) , P. Memeo (4) , B. Meneux (5) , M. Moresco , P. Oesch (4) , C. Porciani (4) , R. Scaramella (4) , S. Arnouts (5) , H. Aussel (4) , P. Capak (18) , J. Kartaltepe (4) , M. Salvato (18) , D. Sanders (19) , N. Scoville (20) , Y. Taniguchi (4) , D. Thompson (21)

1 OAB - INAF - Osservatorio Astronomico di Brera
2 OABO - INAF - Osservatorio Astronomico di Bologna
3 UNIBO - Alma Mater Studiorum Università di Bologna = University of Bologna
4 AUTRES
5 LAM - Laboratoire d'Astrophysique de Marseille
6 OAA - INAF - Osservatorio Astrofisico di Arcetri
7 University of Chicago
8 LATT - Laboratoire Astrophysique de Toulouse-Tarbes
9 INAF- Milano
10 Dipartimento di Fisica
11 Institute of Astronomy [ETH Zürich]
12 Tokai University
13 IASF-Bo - Istituto di Astrofisica Spaziale e Fisica cosmica - Bologna
14 STSci - Space Telescope Science Institute
15 CPT - Centre de Physique Théorique - UMR 6207
16 CPT - Centre de Physique Théorique - UMR 7332
17 IAP - Institut d'Astrophysique de Paris
18 MPIA - Max-Planck-Institut für Astronomie
19 Materials & Process technology
20 CALTECH - California Institute of Technology
21 Sea Mammal Research Unit

(Abridged) We studied the evolution in the B band luminosity function to z~1 in the zCOSMOS 10k sample, for which both accurate galaxy classifications and a detailed description of the local density field are available. The global LF exhibits a brightening of ~0.7 mag in M* from z~0.2 to z~0.9. At low z, late types dominate at faint magnitudes, while the bright end is populated mainly by early types. At higher z, late-type galaxies evolve significantly and, at z~1, the contribution from the various types to the bright end of the LF is comparable. The evolution for early types is in both luminosity and normalization. A similar behaviour is exhibited by late types, but with an opposite trend for the normalization. Studying the role of the environment, we find that the global LF of galaxies in overdense regions has always a brighter M* and a flatter slope. In low density environments, the main contribution to the LF is from blue galaxies, while for high density environments there is an important contribution from red galaxies to the bright end. The differences between the global LF in the two environments are not due to only a difference in the relative numbers of red and blue galaxies, but also to their relative luminosity distributions: the value of M* for both types in underdense regions is always fainter than in overdense environments. The "specular" evolution of late- and early-type galaxies is consistent with a scenario where a part of blue galaxies is transformed in red galaxies with increasing cosmic time, without significant changes in the fraction of intermediate-type galaxies. The bulk of this tranformation in overdense regions probably happened before z~1, while it is still ongoing at lower z in underdense environments.

Domaines: Cosmologie et astrophysique extra-galactique [astro-ph.CO]

E. Zucca, S. Bardelli, M. Bolzonella, G. Zamorani, O. Ilbert, et al.. The zCOSMOS survey: the role of the environment in the evolution of the luminosity function of different galaxy types. Astronomy and Astrophysics - A&A, 2009, 508 (3), pp.1217-1234. ⟨10.1051/0004-6361/200912665⟩. ⟨hal-00421829⟩