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 constrain 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 $|\zeta |<5\times {10}^{-6}$, with the atomic clock tests dominating the constraints. The forthcoming generation of high-resolution ultrastable spectrographs will enable significantly tighter constraints.

• Received 2 January 2015

DOI:https://doi.org/10.1103/PhysRevD.91.103501