رسالة جامعية
The cosmic history of the baryon budget in a hierarchical universe ; L'histoire cosmique des baryons dans un univers hierarchique
| العنوان: | The cosmic history of the baryon budget in a hierarchical universe ; L'histoire cosmique des baryons dans un univers hierarchique |
|---|---|
| المؤلفون: | Rasera, Yann |
| المساهمون: | Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Diderot - Paris VII, Jean-Pierre Chieze(chieze@cea.fr) |
| المصدر: | https://theses.hal.science/tel-00070844Test ; Astrophysique [astro-ph]. Université Paris-Diderot - Paris VII, 2005. Français. ⟨NNT : ⟩. |
| بيانات النشر: | HAL CCSD |
| سنة النشر: | 2005 |
| مصطلحات موضوعية: | star formation rate, star formation history, baryon budget, galaxy formation, hierarchical model, cosmology, light dark matter, galactic winds, gamma ray background, cosmological simulations, analytical model, finite resolution effect, taux de formation d'etoiles, baryons, formation des galaxies, modele hierarchique, cosmologie, matiere noire legere, feedback, overcooling, vents galactiques, fond gamma, simulations cosmologiques, modele analytique, effet de resolution finie, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph] |
| الوصف: | In the framework of the hierarchical model of galaxy formation, small primordial density fluctuations observed on the cosmological microwave background are amplified by gravitational instability leading to the formation of larger and larger halos. The gas collapses and cools in these dark matter potential wells and forms cold centrifugally supported gas discs. These discs are converted into stellar discs that is to say galaxies. The problem in this scenario is the so-called ``overcooling problem'': the resulting amount of stars is greater than the observed one by a factor of four. I have therefore studied the evolution of baryons (hydrogen and helium gas) in the Universe using high resolution hydrodynamical simulations. Based on these results, I have developed a simple analytical model for computing the baryons mass fraction in each of the following phases: stars, cold gas in galactic discs, hot gas in clusters and diffuse gas in the intergalactic medium. The comparison of model results to observations shows us that cosmology controls the cosmic history of star formation. The important cosmological role of galactic winds is also shed to light. They eject the cold gas from discs to hot halos, overcoming the overcooling problem. Finally, I have studied the implication of baryon physics onto the diffuse gamma-ray background from light dark matter particles. ; Durant cette these, j'ai etudie la formation des galaxies grace a des simulations cosmologiques et a un nouveau modele analytique. Dans le cadre du modele standard de formation hierachique des grandes structures, les petites fluctuations primordiales de densite observees sur le fond diffus cosmologique sont amplifiees par la gravite pour donner des halos de matiere noire de plus en plus gros. C'est au sein de ces halos que le gaz s'effondre et se refroidit pour former des disques de gaz froid a support centrifuge. Ces disques sont ensuite convertis en disques stellaires : les galaxies. Le probleme dans ce scenario est celui du sur-refroidissement : une trop ... |
| نوع الوثيقة: | doctoral or postdoctoral thesis |
| اللغة: | French |
| العلاقة: | tel-00070844; https://theses.hal.science/tel-00070844Test; https://theses.hal.science/tel-00070844/documentTest; https://theses.hal.science/tel-00070844/file/these.pdfTest |
| الإتاحة: | https://theses.hal.science/tel-00070844Test https://theses.hal.science/tel-00070844/documentTest https://theses.hal.science/tel-00070844/file/these.pdfTest |
| حقوق: | info:eu-repo/semantics/OpenAccess |
| رقم الانضمام: | edsbas.D1C2980 |
| قاعدة البيانات: | BASE |
| الوصف غير متاح. |