Analysis of the statistical properties of galaxy clusters
Description
Galaxy clusters are one of the most powerful tool of modern cosmology. The abundance of these objects allows to characterize the cosmological properties of the Universe, and the analysis of their physical properties such as mass, temperature or X-ray luminosity of the intra cluster gas, allows to constrain models of formation and evolution of the galaxy clusters. In both cases, the fundamental property is the galaxy cluster mass. It is therefore mandatory to be able to measure it in the most efficient and accurate way. The work presented here follows this problematic: the study of a representative sample of galaxy clusters with masses derived from two different methodologies in order to increase their reliability. This thesis focuses on the gravitational lensing methodology as predicted by the theory of General Relativity. The analysis of the wide-field optical images has been the principal part of the work: selection of the lensed galaxies, estimation of their shape parameters, measure of the shear signal, and the clusters mass reconstruction. To each step of the process are associated errors and limitations, which were highlighted, in particular those due to the large distance of the clusters. The statistical study of the clusters sample allowed to characterize the so-called scaling laws. These relations between the several properties of a galaxy cluster can be used to constrain the model of formation and evolution of structures, and are the main tool used to derive cosmological constraints from galaxy clusters. Their precise calibration requires therefore robust masses. Those derived from the gravitational lensing effect have been compared with the results from the X-ray analysis. For 7 clusters over the 11 in the sample, the masses derived from the two methodologies are in good agreement, thus increasing their reliability. For the other clusters, the observed discrepancies highlight the intrinsic limitations of each method, in particular projection effects and the dynamical state of the cluster. The results obtained on the calibration of the scaling laws are in good agreement with numerous similar works, in particular at lower redshifts. For instance, the presence of non-gravitational physical processes has been revealed, both on the properties of the gas and the galaxy population of the clusters. (author)
Abstract (French)
Les amas de galaxies constituent un des outils majeurs de la cosmologie moderne. Une mesure de l'abondance de ces objets permet de caracteriser les proprietes cosmologiques de l'Univers et l'analyse de leurs differentes proprietes physiques telles que la masse, la temperature ou la luminosite X du gaz intra-amas permet quant a elle de contraindre les modeles de formation et d'evolution de ces objets. Dans les deux cas, la grandeur fondamentale est la masse de l'amas de galaxies. Etre capable de les estimer de la maniere la plus efficace et la plus precise possible est donc une necessite. Le travail presente ici s'inscrit dans cette optique: l'etude d'un echantillon representatif d'amas de galaxies avec des masses deduites de deux analyses totalement differentes afin d'en augmenter la fiabilite. Cette these met l'accent sur la methode qui utilise les effets de lentilles gravitationnelles predits par la theorie de la Relativite Generale. L'analyse d'images optiques grand champ des amas a constitue la plus grande partie de ce travail: selection des galaxies lentillees, estimation de leur forme, mesure du signal de cisaillement gravitationnel et reconstruction de la masse. Chaque etape du processus s'accompagne d'erreurs et de limitations qui ont ete mises en lumiere, en particulier celles attribuees a la distance importante de l'echantillon d'amas. L'etude de celui-ci du point de vue statistique a permis de caracteriser ce qu'on appelle les lois d'echelle. Ces relations entre les differentes grandeurs des amas permettent d'etudier les modeles de formation des structures et constituent l'outil necessaire a une utilisation des amas comme contrainte cosmologique. Leur etalonnage necessite donc une estimation robuste des masses. Celles deduites de l'analyse des effets de lentilles gravitationnelles ont ainsi ete comparees avec les resultats de la seconde methode basee sur l'emission X du gaz intra-amas. Pour 7 des 11 amas de l'echantillon, les masses estimees sont compatibles ce qui augmente leur credibilite. Pour les autres cas, les differences observees mettent en lumiere les limitations intrinseques a chaque methode, en particulier les effets de projection et l'etat dynamique de l'amas. Les resultats obtenus sur la calibration des lois d'echelles sont quant a eux en bon accord avec une grande partie des autres travaux du meme type, notamment sur des amas plus proches. En particulier, la presence de processus physiques non gravitationnels est mise en evidence, a la fois sur les proprietes du gaz et celles de la population des galaxies de l'amas. (auteur)Files
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Additional details
Additional titles
- Original title (French)
- Analyse des proprietes statistiques des amas de galaxies
Publishing Information
- Imprint Pagination
- 278 p.
- Report number
- FRNC-TH--11705
INIS
- Country of Publication
- France
- Country of Input or Organization
- France
- INIS RN
- 52054033
- Subject category
- S79: ASTROPHYSICS, COSMOLOGY AND ASTRONOMY;
- Resource subtype / Literary indicator
- Thesis
- Descriptors DEI
- CALIBRATION; CLASSIFICATION; CORRELATIONS; COSMOLOGICAL MODELS; ELLIPTICAL CONFIGURATION; GALAXY CLUSTERS; GRAVITATIONAL LENSES; IMAGE PROCESSING; LUMINOSITY; MASS; NONLUMINOUS MATTER; PARAMETRIC ANALYSIS; RED SHIFT; SCALING LAWS; SHEAR; SPATIAL RESOLUTION; TEMPERATURE DEPENDENCE; X RADIATION
- Descriptors DEC
- CONFIGURATION; ELECTROMAGNETIC RADIATION; IONIZING RADIATIONS; LENSES; MATHEMATICAL MODELS; MATTER; OPTICAL PROPERTIES; PHYSICAL PROPERTIES; PROCESSING; RADIATIONS; RESOLUTION
Optional Information
- Notes
- [580 refs.]; Available from the INIS Liaison Officer for France, see the INIS website for current contact and E-mail addresses