Imprints of dynamical dark energy on weak-lensing measurements

Abstract

We show that simple models of scalar-field dark energy leave a generic enhancement in the weak-lensing power spectrum when compared to the Λ cold dark matter (ΛCDM) prediction. In particular, we calculate the linear-scale enhancement in the convergence (or cosmic-shear) power spectrum for two best-fitting models of scalar-field dark energy, namely the Ratra-Peebles and SUGRA-type quintessence. Our calculations are based on linear perturbation theory, using gauge-invariant variables with carefully defined adiabatic initial conditions. We find that geometric effects enhance the lensing power spectrum on a broad range of scales, whilst the clustering of dark energy gives rise to additional power on large scales. The dark-energy power spectrum for these models are also explicitly obtained. On degree scales, the total enhancement may be as large as 30-40 per cent for sources at redshift ∼1. We argue that there are realistic prospects for detecting such an enhancement using the next generation of large telescopes. © 2010 The Authors. Journal compilation © 2010 RAS.