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

Abstract

The [O III] $\lambda \lambda 4960,5008$ emission lines in the optical spectra of galaxies and quasars have been widely used to investigate the possible variation of the fine-structure constant $\alpha$ 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 $\alpha$ variation $\Delta \alpha /\alpha$ 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 $\Delta \alpha /\alpha =(0.5\pm 3.7)\times 10^{-4}$, which suggests that there is no evidence of varying $\alpha$ on the explored cosmological timescales. Assuming a linear variation, the mean rate of change in $\Delta \alpha /\alpha$ is limited to be $(-3.4\pm 2.4)\times 10^{-13}$ $\mathrm{y}{\mathrm{r}}^{-1}$ in the last 7.0 Gyr. While our LAMOST-based constraint on $\Delta \alpha /\alpha$ 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.

Comments: Updated to match the published version in RAA