Cosmic Structure Growth and Dark Energy
Dark energy has a dramatic effect on the dynamics of the universe, causing the recently discovered acceleration of the expansion. The dynamics are also central to the behavior of the growth of large scale structure, offering the possibility that observations of structure formation provide a sensitive probe of the cosmology and dark energy characteristics. In particular, dark energy with a time varying equation of state can have an influence on structure formation stretching back well into the matter dominated epoch. We analyze this impact, first calculating the linear perturbation results, including those for weak gravitational lensing. These dynamical models possess definite observable differences from constant equation of state models. Then we present a large scale numerical simulation of structure formation, including the largest volume to date involving a time varying equation of state. We find the halo mass function is well described by the Jenkins et al. mass function formula. We also show how to interpret modifications of the Friedmann equation in terms of a time variable equation of state. The results presented here provide steps toward realistic computation of the effect of dark energy in cosmological probes involving large scale structure, such as cluster counts, Sunyaev-Zel'dovich effect, or weak gravitational lensing.