We investigate the origin of the colour-magnitude relation (CMR) observed in
cluster galaxies by using a combination of a cosmological N-body simulation of
a cluster of galaxies and a semi-analytic model of galaxy formation. The
departure of galaxies in the bright end of the CMR with respect to the trend
denoted by less luminous galaxies could be explained by the influence of minor
mergersComment: ASP Conference, Galaxies in Isolation; Exploring Nature vs. Nurture;
  201

Bassino, Lilia P.

Castelli, Analia Smith

Cora, Sofia A.

Jimenez, Noelia

Publications of the Astronomical Society of the Pacific

English

arXiv

We investigate the origin of the colour-magnitude relation (CMR) observed
in cluster galaxies by using a combination of a cosmological N-body simulation
of a cluster of galaxies and a semi-analytic model of galaxy formation. The
departure of galaxies in the bright end of the CMR with respect to the trend
denoted by less luminous galaxies could be explained by the influence of minor
mergers.Fil: Jiménez, Noelia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Astrofísica de La Plata; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Cora, Sofia Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Instituto de Astrofísica de la Plata; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Smith Castelli, Analia Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Astrofísica de La Plata; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Bassino, Lilia Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Astrofísica de La Plata; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentin

Jiménez, Noelia

Cora, Sofia Alejandra

Smith Castelli, Analia Viviana

Bassino, Lilia Patricia

CONICET Digital

**FULL TITLE**ASP Conference Series, Vol. **VOLUME**, **YEAR OF PUBLICATION****NAMES OF EDITORS**Modeling the Color Magnitude Relation for GalaxyClustersN. Jiménez,1,2 S. A. Cora,1,2 A. Smith Castelli,1,2 and L. P. Bassino,1,21Facultad de Ciencias Astronómicas y Geof́ısicas (FCAG) de laUniversidad Nacional de La Plata (UNLP), Argentina.2Instituto de Astrof́ısica de La Plata (CCT La Plata, CONICET)Abstract.We investigate the origin of the colour-magnitude relation (CMR) observedin cluster galaxies by using a combination of a cosmological N-body simulationof a cluster of galaxies and a semi-analytic model of galaxy formation. Thedeparture of galaxies in the bright end of the CMR with respect to the trenddenoted by less luminous galaxies could be explained by the influence of minormergers.We consider a simulated galaxy cluster with virial mass ≈ 1.3×1015 h−1 M⊙,(Dolag et al. 2005). The semi-analtytic model of galaxy formation used (Lagos,Cora & Padilla 2008) considers gas cooling, star formation, galaxy mergers, discinstabilities, metal enrichment and feeback from supernovae and active galacticnuclei. We compare the photometric properties of simulated early-type galaxies(those with a bulge component comprising 80 per cent of the total stellar mass)with those of the early-type galaxies in the central region of the Antlia cluster(Smith Castelli et al. 2008), using the Washington photometric system. Wefind good agreement between the general trend of simulated and observed CMR.However, the more massive galaxies (−22. < MT1 < −19.) depart from the fit toobserved data, displaying an almost constant colour (C −T1 ≈ 1.7), as detectedin other clusters.We select galaxies in six magnitude bins within the range −22. < MT1 <−16. and analyse the evolution of their content of cold gas and the averagenumber of minor mergers suffered by these galaxies. We find an increase of thelatter quantity at low redshift for the more luminous galaxies. These galaxiesare also characterized by a low content of cold gas which dramatically decreasessince z ≈ 2. The combination of these two effects would yield to an increase ofthe luminosity without strongly affecting the galaxy colour. We will deepen theinvestigation on the origin of the CMR bright end with the aim of disentanglingthe role played by dry mergers in determining the properties of the more massivegalaxies.ReferencesLagos, C., Cora S. A., & Padilla N. D. 2008, MNRAS, 388, 587Dolag, K., Vazza, F., Brunetti, G., & Tormen, G. 2005, MNRAS, 364, 753Smith Castelli, A., Bassino, L., Richtler, T., et al. 2008, MNRAS, 386, 23111

Modeling the color magnitude relation for galaxy clusters

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Modeling the Color Magnitude Relation for Galaxy Clusters

Modeling the Color Magnitude Relation for Galaxy Clusters

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