Measuring the Time Variation of the Fine-structure Constant with Quasars Detected by LAMOST

This is the authors' abstract. We don't add key points for this paper.

The [O III] λλ\ 4960,5008 emission lines in the optical spectra of galaxies and quasars have been widely used to investigate the possible variation of the fine-structure constant α over cosmic time. In this work, we utilize the Large Sky Area Multi-object Fiber Spectroscopic Telescope (LAMOST) quasar survey, for the first time, to measure the relative α variation Δα/α in time through the [O III] doublet method. From the LAMOST Data Release 9 quasar catalog, we refine a sample of 209 quasar spectra with strong and narrow [O III] emission lines over a redshift range of $0<z<0.8$. Analysis on all of the 209 spectra obtains Δα/α = (0.5 ± 3.7) × 10⁻⁴, which suggests that there is no evidence of varying α on the explored cosmological timescales. Assuming a linear variation, the mean rate of change in Δα/α is limited to be (-3.4 ± 2.4)× 10⁻¹³ yr⁻¹ in the last 7.0 Gyr. While our LAMOST-based constraint on Δα/α is not competitive with those of the Sloan Digital Sky Survey (SDSS) quasar observations, our analysis serves to corroborate the results of SDSS with another independent survey.