Large scale structure formation in cosmological simulations of coupled dark energy models
My master research project consists in studying the matter density perturbations in the non linear regime under different cosmological dark energy models. The best tool for this is to study the evolution of the matter power spectrum which is just the Fourier transform of the two-point correlation function of the density contrast. Structure formation plays an important role in current cosmology, since it can be used to test different cosmological models by comparing their predictions with observations from galaxy surveys and estimation of mass potentials through weak lensing. Numerical N-body simulations are an important tool here, since they provide the only way of evolving the dynamics of many particle systems under a complicated gravitational non linear behaviour.
In this work, we study in detail the evolution and properties of the matter power spectrum of Dark Matter in coupled Dark Energy models. The spectra are extracted from the CoDECS set of cosmological N-body simulations—the most powerful tool to study the evolution of nonlinear gravitational and hydrodynamical processes in structure formation where linear perturbation theory breaks down. We ﬁnd a ﬁt function that describes the nonlinear power spectrum of Dark Matter density ﬂuctuations under the inﬂuence of a ﬁfth force caused by a constant coupling to a Quintessence ﬁeld with an exponential potential. The validity of the ﬁt function is demonstrated for all available simulations with constant couplings and redshifts below 1.6. This formula can be used in principle to test the predictions of this Quintessence model against future observational surveys of the large-scale matter distribution in the Universe without the need for additional computing-intensive N-body simulations.