PhD Defense

Dark Matter distribution and cosmological simulations – Characterization with the Minkowski Functionals

PhD defense (in English) by Guillaume Bonnet.

Abstract

This thesis addresses the formation and evolution of structures and more specifically the dark matter distribution within halos in a cosmological context. We start by introducing the general context of structure formation in cosmology. Then we investigate the ability of the Minkowski Functionals (MFs) to probe bounded structures like halos. We use the MFs to characterize the actual morphology of halos, only partially captured by smooth density profile, going beyond the spherical or ellipsoidal symmetry. We employ semi-analytical halos with NFW and alpha,beta,gamma-profile and spherical or ellipsoidal shape to obtain a clear interpretation of MFs as function of inner and outer slope, concentration and sphericity parameters. We use the same models to mimic the density profile of N-body halos, showing that their MFs clearly differ, as they are sensitive to internal substructures. This highlights the benefit of MFs at the halo scales as promising statistics to improve the spatial modelling of dark matter. Finally, we study the impact of dark energy on the morphology of halos. We use a set of auxiliary simulations of the DEUS-FUR project with different dark energy candidates such as a standard cosmological constant, a phantom candidate with constant equation of state w=-1.2 and a dynamical Ratra–Peebles model. We compare the morphology of halos between these models with density profile, concentration, shape parameters, relaxation parameters and MFs. We show that different dark energy models produce different morphologies of halos for small galaxy groups at z=0 and for large galaxy clusters at z=0.5. This confirms that the halo scale can be used to discriminate different cosmological models.

Jury:

Pier-Stefano CORASANITI, LUTH, Rapporteur

Giovanni COVONE, Université de Naples, Rapporteur 
                
Geneviève SOUCAIL, IRAP, Présidente du jury 
               
Sophie MAUROGORDATO, Université Côte d’Azur, Examinatrice 

Supervisors :
                
Philippe AMRAM, LAM, Directeur de thèse 
                
Emmanuel NEZRI, LAM, Co-directeur de thèse 

Guests :

Carlo Schimd, LAM 
                
Katarina Kraljic, LAM