Probing the time-variation of the fine-structure constant: Results based on Si IV doublets from a UVES sample

Abstract

We report a new constraint on the variation of the fine-structure constant based on the analysis of 15 Si IV doublets selected from a ESO-UVES sample. We find Δ α/α = (+0.15 ± 0.43) × 10^-5 over a redshift range of 1.59 ≤ z ≤ 2.92 which is consistent with no variation in α. This result represents a factor of three improvement on the constraint on Δα/α based on Si IV doublets compared to the published results in the literature. The alkali doublet method used here avoids the implicit assumptions used in the many-multiplet method that chemical and ionization inhomogeneities are negligible and isotopic abundances are close to the terrestrial value.