1305.4509 (Didam Duniya et al.)

Clustering of quintessence on horizon scales and its imprint on HI intensity mapping    [PDF]

Didam Duniya, Daniele Bertacca, Roy Maartens

Quintessence can cluster only on horizon scales. What is the effect of this on the observed matter distribution? To answer this we need a relativistic approach that goes beyond the standard Newtonian calculation and deals properly with large scales. Such an approach has recently been developed for the case when dark energy is vacuum energy, which does not cluster at all. We extend this relativistic analysis to deal with dynamical dark energy. Using three quintessence potentials as examples, we compute the angular power spectrum for the case of an HI intensity map survey. Compared to the concordance model with the same Omega_m0 and H_0, quintessence boosts the angular power by up to ~15% at high redshifts, while power in the two models converges at low redshifts. The difference is mainly due to the background evolution. The dark energy perturbations make only a small contribution on the largest scales, and a negligible contribution on smaller scales. Ironically, the dark energy perturbations remove the false boost of large-scale power that arises if we impose the (unphysical) assumption that the dark energy is smooth.

View original: http://arxiv.org/abs/1305.4509