Constraints on a possible variation of the fine structure constant from galaxy cluster data
We propose a new method to probe a possible time evolution of the fine structure constant $α$ from X-ray and Sunyaev-Zeldovich measurements of the gas mass fraction ($f_{gas}$) in galaxy clusters. Taking into account a direct relation between variations of $α$ and violations of the distance-duality relation, we discuss constraints on $α$ for a class of dilaton runaway models. Although not yet competitive with bounds from high-$z$ quasar absorption systems, our constraints, considering a sample of 29 measurements of $f_{gas}$, in the redshift interval $0.14 < z < 0.89$, provide an independent estimate of $α$ variation at low and intermediate redshifts. Furthermore, current and planned surveys will provide a larger amount of data and thus allow to improve the limits on $α$ variation obtained in the present analysis.