Probing variation of the fine-structure constant in runaway dilaton models using Strong Gravitational Lensing and Type Ia Supernovae

In order to probe a possible time variation of the fine-structure constant ( $$\alpha $$ ), we propose a new method based on Strong Gravitational Lensing and Type Ia Supernovae observations. By considering a class of runaway dilaton models, where $$\frac{\Delta \alpha }{\alpha }= - \gamma \ln {(1+z)}$$ , we obtain constraints on $$\frac{\Delta \alpha }{\alpha }$$ at the level $$\gamma \sim 10^{-2}$$ ( $$\gamma $$ captures the physical properties of the model). Since the data set covers the redshift range $$0.075 \le z \le 2.2649$$ , the constraints derived here provide independent bounds on a possible time variation of $$\alpha $$ at low, intermediate and high redshifts.