Bibcode
Domínguez-Sánchez, H.; Pozzi, F.; Gruppioni, C.; Cimatti, A.; Ilbert, O.; Pozzetti, L.; McCracken, H.; Capak, P.; Le Floch, E.; Salvato, M.; Zamorani, G.; Carollo, C. M.; Contini, T.; Kneib, J.-P.; Le Fèvre, O.; Lilly, S. J.; Mainieri, V.; Renzini, A.; Scodeggio, M.; Bardelli, S.; Bolzonella, M.; Bongiorno, A.; Caputi, K.; Coppa, G.; Cucciati, O.; de la Torre, S.; de Ravel, L.; Franzetti, P.; Garilli, B.; Iovino, A.; Kampczyk, P.; Knobel, C.; Kovač, K.; Lamareille, F.; Le Borgne, J.-F.; Le Brun, V.; Maier, C.; Mignoli, M.; Pelló, R.; Peng, Y.; Perez-Montero, E.; Ricciardelli, E.; Silverman, J. D.; Tanaka, M.; Tasca, L. A. M.; Tresse, L.; Vergani, D.; Zucca, E.
Bibliographical reference
Monthly Notices of the Royal Astronomical Society, Volume 417, Issue 2, pp. 900-915.
Advertised on:
10
2011
Citations
56
Refereed citations
55
Description
The goal of this work is to study the evolution of high-redshift (z≥
1.4) quiescent galaxies over an effective area of ˜1.7
deg2 in the COSMOS field. Galaxies have been divided
according to their star formation activity and the evolution of the
different populations, in particular of the quiescent galaxies, has been
investigated in detail. We have studied an IRAC (mag 3.6
μm < 22.0) selected sample of ˜18 000 galaxies at
z≥ 1.4 in the COSMOS field with multiwavelength coverage extending
from the U band to the Spitzer 24 μm one. We have derived accurate
photometric redshifts (?) through a SED-fitting procedure. Other
important physical parameters [masses, ages and star formation rates
(SFR)] of the galaxies have been obtained using Maraston models. We have
divided our sample into actively star-forming, intermediate and
quiescent galaxies depending on their specific star formation rate (SSFR
= SFR/M). We have computed the galaxy stellar mass function (GSMF) of
the total sample and the different populations at z= 1.4-3.0. We have
studied the properties of high-redshift quiescent galaxies finding that
they are old (1-4 Gyr), massive (˜ 1010.65
M&sun;), weakly star-forming stellar populations with low
dust extinction [E(B-V) ≤ 0.15] and small e-folding time-scales
(τ˜ 0.1-0.3 Gyr). We observe a significant evolution of the
quiescent stellar mass function from 2.5 < z < 3.0 to 1.4 < z
< 1.6, increasing by ˜1 dex in this redshift interval. We find
that z˜ 1.5 is an epoch of transition of the GSMF: while the GSMF
at z≳ 1.5 is dominated by the star-forming galaxies at all stellar
masses, at z≲ 1.5 the contribution to the total GSMF of the
quiescent galaxies is significant and becomes higher than that of the
star-forming population for M≥ 1010.75 M&sun;.
The fraction of star-forming galaxies decreases from 60-20 per cent from
z˜ 2.5-3.0 to 1.4-1.6 for M˜ 1011.0
M&sun;, while the quiescent population increases from 10-50
per cent at the same redshift and mass intervals. We compare the
fraction of quiescent galaxies derived with that predicted by
theoretical models and find that the Kitzbichler & White model,
implemented on the Millennium Simulation, is the one that better
reproduces the shape of the data. Finally, we calculate the stellar mass
density of the star-forming and quiescent populations as a function of
redshift and find that there is already a significant number of
quiescent galaxies at z > 2.5 (logρ[M&sun;
Mpc-3]˜ 6), meaning that efficient star formation had
to take place before that time.