Measuring the Time Variation of the Fine-structure Constant with Quasars Detected by LAMOST
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 $Δα/α= (0.5 \pm 3.7) \times 10^{-4}$, 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 $(-3.4 \pm 2.4)\times 10^{-13}$ $\mathrm{yr^{-1}}$ 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.