Is the Dynamics of Tracking Dark Energy Detectable?

TL;DR

This paper discusses how early universe constraints, especially nucleosynthesis, limit the detectability of tracking dark energy models, suggesting that their dynamics may remain hidden until advanced future experiments.

Contribution

It reveals that nucleosynthesis constraints significantly restrict tracking quintessence models, challenging the effectiveness of standard parametrizations and impacting future dark energy survey strategies.

Findings

Nucleosynthesis constrains |w'(0)| < 0.2 for models considered.

Standard CPL parametrization cannot match nucleosynthesis bounds.

Dark energy dynamics may be undetectable until next-generation experiments.

Abstract

We highlight the unexpected impact of nucleosynthesis and other early universe constraints on the detectability of tracking quintessence dynamics at late times, showing that such dynamics may well be invisible until the unveiling of the Stage-IV dark energy experiments (DUNE, JDEM, LSST, SKA). Nucleosynthesis forces |w'(0)| < 0.2 for the models we consider and strongly limits potential deviations from LCDM. Surprisingly, the standard CPL parametrisation, w(z) = w_0 + w_a z/(1+z), cannot match the nucleosynthesis bound for minimally coupled tracking scalar fields. Given that such models are arguably the best-motivated alternatives to a cosmological constant these results may significantly impact future cosmological survey design and imply that dark energy may well be dynamical even if we do not detect any dynamics in the next decade.