Fine-structure constant constraints on dark energy

TL;DR

This paper combines astrophysical, atomic clock, and supernova data to constrain models where dark energy and variations in the fine-structure constant are linked, finding current data tightly limits their coupling.

Contribution

It provides the first comprehensive analysis constraining the coupling between dark energy and the fine-structure constant using multiple observational probes.

Findings

Current data constrain the coupling parameter to |ζ|<5×10⁻⁶ at 95% confidence.

Atomic clock tests dominate the constraints on the model.

Future spectrographs will significantly improve these constraints.

Abstract

We use astrophysical and atomic clock tests of the stability of the fine-structure constant $\alpha$, together with Type Ia supernova and Hubble parameter data, to constrain the simplest class of dynamical dark energy models where the same degree of freedom is assumed to provide both the dark energy and (through a dimensionless coupling, $\zeta$, to the electromagnetic sector) the $\alpha$ variation. We show how current data tightly constrains a combination of $\zeta$ and the dark energy equation of state $w_0$. At the $95\%$ confidence level and marginalizing over $w_0$ we find $|\zeta|<5\times10^{-6}$, with the atomic clock tests dominating the constraints. The forthcoming generation of high-resolution ultra-stable spectrographs will enable significantly tighter constraints.