Evolution of galaxies: interactions, mergers, and gas accretion
type: Dataset
description: Studying present day properties of galaxies can give information both on their past evolution and on the matter content of the Universe. Morphological and kinematical properties can be studied statistically, as a function of environment, with recent observations. To interpret these observed properties, we have modelled the formation and past evolution of galaxies with numerical simulations. The codes that are used, already existing for a part, and developed during the thesis for the other part, model the gravitational dynamics of stars, gas clouds and dark matter, the dissipative hydrodynamic nature of interstellar gas, and star formation. Outputs from the simulations can then be compared to observations to understand which processes have led to the current state of galaxies. In a first part, we study the morphology of isolated galaxies. We show that most spiral galaxies have a bar -- an elongated central concentration of stars. This bar should have been destroyed in a few billions year by angular momentum transfer to the interstellar medium. The ubiquity of bars since 10 billion years then requires them to be reformed or strengthen by an external process. This can be explained only if galaxies accrete large amounts of gas from the intergalactic medium. The study of disk lopsidedness in spiral galaxies also argues towards this conclusion. We estimate the typical accretion rate, of w few solar masses per year for a Milky-Way like galaxy. This give strong constraints for cosmological models: the Universe must contain enough baryonic matter, tat must not be converted into stars too rapidly, so that enough gas remains to be accreted and increase the mass of spiral galaxies by a few tens of percent below the epoch of redshift z=1. Then, galaxies have grown by a gas accretion process, for a part, by collisions and mergers also play an important role in their evolution. It is well-known that equal-mass galaxy mergers from elliptical galaxies. We show that even mergers will…
landing page: https://theses.hal.science/tel-00079377
keyword: cinematique
keyword: cosmologie
keyword: cosmology
keyword: dark-matter
keyword: dynamics
keyword: ellipticals
keyword: elliptiques
keyword: evolution
keyword: galaxies
keyword: infoeu-reposemanticsdoctoralthesis
keyword: kinematics
keyword: matiere-noire
keyword: numerical-simulations
keyword: sduastrsciences-of-the-universe-physicsastrophysics-astro-ph
keyword: simulations-numeriques
keyword: spirales
keyword: spirals
keyword: theses
issued: 2026-05-14T05:10:26.123258
modified: 2026-05-14T05:10:26.123264
language: fr
contact point: Organization
  fn: CCSD

test_moissonnage_selune
type: Agent

Evolution of galaxies: interactions, mergers, and gas accretion
type: Distribution
format: HTML
access URL: https://theses.hal.science/tel-00079377
issued: 2026-05-14T05:10:26.135673
modified: 2026-05-14T05:10:26.087781