SIMBAD references

A statistical analysis of fine splitting of C IV, N V, O VI, Mg II, Al III and Si IV doublet absorption lines in quasar spectra is carried out in order to estimate a possible time variation of the fine-structure constant α= e² (h/2π)c over cosmological time scales t∼10¹⁰yr. The observational basis of the analysis is a catalogue of 1414 pairs of wavelengths with redshifts z = 0.2 - 3.7, compiled from data published in 1980-1992. Robust statistical estimates like the "trimmed mean" are used as well as the least squares. No statistically significant time variation of α is found. The estimate α^–1dα/dz = (-0.6±2.8)10^–4 is obtained. For the 95% significance level, an upper bound on the rate of a relative variation of the fine-structure constant is |α^–1dα/dz| < 5.6x10^–4, which corresponds approximately to |α^–1dα/dt| < 4x10^–14 yr^–1. This limit represents the strongest up-to-date restriction on the possible time variation of α for the epoch 0.2 ≤ z ≲ 4.