We compare the results from a state-of-the-art semianalytic model of galaxy formation with spectrophotometric observations of distant galaxy clusters observed in the range 0.8 <= z <= 1.3. We investigate the properties of their red sequence (RS) galaxies and compare them with those of the field at the same redshift. In our model we find that (1) a well-defined, narrow RS is obtained already by z approximate to 1.2; this is found to be more populated than the field RS, analogously to what is observed and predicted at z = 0; (2) the predicted U-V rest-frame colors and scatter of the cluster RS at z = 1.2 have average values of 1 and 0.15, respectively, with a cluster-to-cluster variance of approximate to 0.2 and approximate to 0.06, respectively. The scatter of the RS of cluster galaxies is approximate to 5 times smaller than the corresponding field value; (3) when the RS galaxies are considered, the mass growth histories of field and cluster galaxies at z = 1.2 are similar, with 90% of the stellar mass of RS galaxies at z = 1.2 already formed at cosmic times t = 2.5 Gyr, and 50% at t = 1 Gyr; and (4) the predicted distribution of stellar ages of RS galaxies at z = 1.2 peaks at 3.7 Gyr for both cluster and field populations; however, for the latter the distribution is significantly skewed toward lower ages. When compared with observations, the above findings show an overall consistency, although the average value Delta(U-V) approximate to 0.07 of the observed cluster RS scatter at z approximate to 1.2 is smaller than the corresponding model central value. We discuss the physical origin and the significance of the above results in the framework of cosmological galaxy formation.

The red sequence of high-redshift clusters: A comparison with cosmological galaxy formation models

ROSATI, Piero;
2008

Abstract

We compare the results from a state-of-the-art semianalytic model of galaxy formation with spectrophotometric observations of distant galaxy clusters observed in the range 0.8 <= z <= 1.3. We investigate the properties of their red sequence (RS) galaxies and compare them with those of the field at the same redshift. In our model we find that (1) a well-defined, narrow RS is obtained already by z approximate to 1.2; this is found to be more populated than the field RS, analogously to what is observed and predicted at z = 0; (2) the predicted U-V rest-frame colors and scatter of the cluster RS at z = 1.2 have average values of 1 and 0.15, respectively, with a cluster-to-cluster variance of approximate to 0.2 and approximate to 0.06, respectively. The scatter of the RS of cluster galaxies is approximate to 5 times smaller than the corresponding field value; (3) when the RS galaxies are considered, the mass growth histories of field and cluster galaxies at z = 1.2 are similar, with 90% of the stellar mass of RS galaxies at z = 1.2 already formed at cosmic times t = 2.5 Gyr, and 50% at t = 1 Gyr; and (4) the predicted distribution of stellar ages of RS galaxies at z = 1.2 peaks at 3.7 Gyr for both cluster and field populations; however, for the latter the distribution is significantly skewed toward lower ages. When compared with observations, the above findings show an overall consistency, although the average value Delta(U-V) approximate to 0.07 of the observed cluster RS scatter at z approximate to 1.2 is smaller than the corresponding model central value. We discuss the physical origin and the significance of the above results in the framework of cosmological galaxy formation.
2008
Menci, N; Rosati, Piero; Gobat, R; Strazzullo, V; Rettura, A; Mei, S; Demarco, R.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11392/1854047
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