2007A&A...466.1077L

We probe the evolution of the fine-structure constant α with cosmic time. Accurate positions of the FeII lines λ1608, λ2382, and λ2600 are measured in the z_abs=1.84 absorption system from a high-resolution (FWHM∼3.8km/s) and high signal-to-noise (S/N>100) spectrum of the quasar Q 1101-264 (z_em=2.15, V=16.0), integrated for 15.4h. The Single Ion Differential α Measurement (SIDAM) procedure and the Δχ² method are used to set constraints on Δα/α. We have found a relative radial velocity shift between the λ1608 and λλ2382,2600 lines of Δv=-180±85m/s (both random and systematic errors are included), which, if real, would correspond to Δα/α=(5.4±2.5)x10^–6 (1σ C.L.). Considering the strong implications of a such variability, additional observations with comparable accuracy at redshift z∼1.8 are required to confirm this result.