Stringent limit on space-time variation of fine-structure constant using high-resolution of quasar spectra

We have obtained a new limit on the space-time variation of the fine-structure constant  using the observations of Mg II line in quasar J110325-264515 spectra with redshift z_abs =1.8389. The obtained parameter is Δα/α =(−0.155 ± 0.728) × 10⁻⁶. It was derived from the comparison between the quasar J110325-264515 spectra and the laboratory sample spectra. The obtained result appears as a new highly sensitive probe of the cosmological variability of the fine-structure constant. From the relative spectra of the Mg II, we found the most stringent constraint up today on Δα/α comparing to the previously published results.