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ÉVOLUTION DES PROPRIÉTÉS STRUCTURELLES DES GALAXIES DE TYPE PRÉCOCE DANS DIFFÉRENTS ENVIRONNEMENTS

Abstract : The mass assembly of massive galaxies is still an open question. In particular, there is a large debate about the evolution leading to the formation of massive early-type galaxies (ETGs) observed today, since the discovery of massive passive galaxies at z ~ 1-2 more compact than their local counter-parts. Two physical processes are usually invoked to explain the size growth of these galaxies : gas expulsion or dry minor mergers, but none of them is able to reproduce all the observed trends. Environment is an additional variable that can be used to disentangle between different scenarios and which has been poorly explored up to now. In that contex, z > 1 is an interesting epoch to study environmental dependence of the sizes of ETGs since the first massive clusters start to appear at that time. If galaxies ending-up in these massive structures have for some reason been processed differently or more rapidly than galaxies living in the field, the effects should be visible at that time. In this work, I analyze the mass-size relation and size evolution of passive early-type galaxies in a sample of nine massive galaxy clusters in the redshift range 0.8 < z < 1.6 and compare it to an homogeneous sample of field galaxies. All properties (size, mass and morphology) are derived on the same way. Cluster galaxy selection include galaxies classified as early-type with stellar masses above 3 * 10^10 M lying on the red sequence of each cluster. Field galaxies have been selected according to the same criteria. The main result is that we do not detect any significant differences in the mass-size relation and size evolution of early-type galaxies living in the field and in clusters. Our results, combined with previous works, suggest that the imprint of environment on galaxy sizes is very weak from at least z ~ 1.5. This result is independent of the stellar mass range that we use. Besides, we detect a morphological dependence of the mass-size relation for elliptical and lenticular galaxies. Lenticulars appear on average more compact at fixed stellar mass than ellipticals and evolve faster from z ~ 1.5 to present. They are ~ 40% smaller at z = 1 and only ~ 10% smaller at z = 0. Elliptical galaxies dominate the galaxy population beyond 10^11 Msun . We compare our results with the predictions of two semi-analytical models based on the Millenium merger trees. They predict a behaviour broadly consistent with our findings at 1-2 sigma. This puts constraints on the properties of galaxy evolution processes.
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https://tel.archives-ouvertes.fr/tel-00878449
Contributor : Lauriane Delaye <>
Submitted on : Wednesday, October 30, 2013 - 10:07:12 AM
Last modification on : Wednesday, October 14, 2020 - 3:58:14 AM
Long-term archiving on: : Friday, January 31, 2014 - 4:31:48 AM

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  • HAL Id : tel-00878449, version 1

Citation

Lauriane Delaye. ÉVOLUTION DES PROPRIÉTÉS STRUCTURELLES DES GALAXIES DE TYPE PRÉCOCE DANS DIFFÉRENTS ENVIRONNEMENTS. Cosmologie et astrophysique extra-galactique [astro-ph.CO]. Université Paris-Diderot - Paris VII, 2013. Français. ⟨tel-00878449⟩

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