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.

Updated to match the published version in RAA

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