Testable dark energy predictions from current data

Abstract

Given a class of dark energy models, constraints from one set of cosmic acceleration observables make predictions for other observables. Here we present the allowed ranges for the expansion rate HðzÞ, distances DðzÞ, and the linear growth function GðzÞ (as well as other, derived growth observables) from the current combination of cosmological measurements of supernovae, the cosmic microwave background, baryon acoustic oscillations, and the Hubble constant. With a cosmological constant as the dark energy and assuming near-minimal neutrino masses, the growth function is already predicted to better than 2% precision at any redshift, with or without spatial curvature. Direct measurements of growth that match this precision offer the opportunity to stringently test and potentially rule out a cosmological constant. While predictions in the broader class of quintessence models are weaker, it is remarkable that they are typically only a factor of 2-3 less precise than forecasted predictions for future space-based supernovae and Planck CMB measurements. In particular, measurements of growth at any redshift, or the Hubble constant H 0 , that exceed ÃCDM predictions by substantially more than 2% would rule out not only a cosmological constant but also the whole quintessence class, with or without curvature and early dark energy. Barring additional systematic errors hiding in the data, such a discovery would require more exotic explanations of cosmic acceleration such as phantom dark energy, dark energy clustering, or modifications of gravity.

Future CMB constraints on early, cold, or stressed dark energy

“…[8] and references therein). Dark energy could therefore be different from a cosmological constant, and indeed many diverse models are also consistent with the data [9][10][11].…”

Dark Energy

“…For more studies concerning the growth factor and its application on the probe of dark energy, see e.g. [491,492,493,494].…”

Comparison of piecewise-constant methods for dark energy

“…Another advantage of the PCA is that there is no need to specify the cosmology; i.e. it is a model-independent approach, as the PCA will give us a set of functions that better describes the data [8], [9], [10], [11], [12], [13]. More details on the procedure of the PCA and the relevant sets of equations for each approach are also presented in Sec.…”