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Journal of Classification

, Volume 23, Issue 1, pp 57–78 | Cite as

Astrocladistics: A Phylogenetic Analysis of Galaxy Evolution II. Formation and Diversification of Galaxies

  • Didier Fraix-Burnet
  • Philippe Choler
  • Emmanuel J.P. Douzery
  • Anne Verhamme
Article

Abstract

This series of papers is intended to evaluate astrocladistics in reconstructing phylogenies of galaxies. The objective of this second paper is to formalize the concept of galaxy formation and to identify the processes of diversification. We show that galaxy diversity can be expected to organize itself in a hierarchy. In order to better understand the role of mergers, we have selected a sample of 43 galaxies from the GALICS database built from simulations with a hybrid model for galaxy formation studies. These simulated galaxies, described by 119 characters and considered as representing still undefined classes, have experienced different numbers of merger events during evolution. Our cladistic analysis yields a robust tree that proves the existence of a hierarchy. Mergers, like interactions (not taken into account in the GALICS simulations), are probably a strong driver for galaxy diversification. Our result shows that mergers participate in a branching type of evolution, but do not seem to play the role of an evolutionary clock.

Keywords

Cladistic Analysis Star Formation Rate Galaxy Formation Basic Constituent Galaxy Evolution 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer Science + Business Media Inc. 2006

Authors and Affiliations

  • Didier Fraix-Burnet
    • 1
  • Philippe Choler
    • 2
  • Emmanuel J.P. Douzery
    • 3
  • Anne Verhamme
    • 1
  1. 1.Laboratoire d’Astrophysique de GrenobleGrenobleFrance
  2. 2.Laboratoire d’ Ecologie AlpineGrenobleFrance
  3. 3.Laboratoire de Paleontologie, Phylogenie et Paleobiologie, Institut des Sciences de l’ Evolution de MontpellierMontpellierFrance

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