Limits on the Time Variation of the Electromagnetic Fine-Structure Constant in the Low Energy Limit from Absorption Lines in the Spectra of Distant Quasars

We present the results of a detailed many-multiplet analysis performed on a new sample of Mgii systems observed in high quality quasar spectra obtained using the Very Large Telescope. The weighted mean value of the variation in α derived from our analysis over the redshift range 0.4≤z≤2.3 is Δα/α=(-0.06±0.06)×10^-5. The median redshift of our sample (z≃1.55) corresponds to a look-back time of 9.7Gyr in the most favored cosmological model today. This gives a 3σ limit, -2.5×10^-16≤(Δα/αΔt)≤+1.2×10^-16 yr^-1, for the time variation of α, that forms the strongest constraint obtained based on high redshift quasar absorption line systems.