%0 Generic
%A Ayaita, Youness
%D 2013
%F heidok:15128
%R 10.11588/heidok.00015128
%T Cosmology with strongly coupled quintessence
%U https://archiv.ub.uni-heidelberg.de/volltextserver/15128/
%X The cosmological constant problem motivates alternative approaches for explaining the observed accelerated expansion of the Universe. Quintessence models describe a dynamical dark energy component in terms of a scalar field, the cosmon; in contrast to the cosmological constant scenario, the predicted amount of present dark energy is, generically, comparable to that of matter. The simplest models lack, however, a natural explanation why the dark energy has started to dominate the energy budget of the Universe just around the present cosmic epoch. Growing neutrino quintessence, proposing a coupling between the cosmon and the neutrinos, is a potential solution to this coincidence problem. At the level of perturbations in the energy densities, this coupling mediates an attractive force between the neutrinos stronger than gravity. This has drastic consequences for quantitative analyses of the model. The standard technical repertoire of linear perturbation theory and Newtonian N-body simulations fails. Even the evolution of the Friedmann-Lemaître-Robertson-Walker background depends on the nonlinear perturbations by virtue of a backreaction effect. We present a comprehensive method, accompanied with an improved physical understanding, for a quantitatively reliable investigation of the model and open the door to a systematic exploration of its parameter space and a confrontation with observational constraints.