Constraints on the variation of the fine-structure constant at 3<z<10 with JWST emission-line galaxies

Abstract

We present constraints on the spacetime variation of the fine-structure constant $\hat{I}\pm$ at redshifts $2.5\le z<9.5$ using JWST emission-line galaxies. The galaxy sample consists of 621 high-quality spectra with strong and narrow [O III] $\hat{I}»\hat{I}»$4959,5007 doublet emission lines from 578 galaxies, including 232 spectra at $z>5$. The [O III] doublet lines are arguably the best emission lines to probe the variation in $\hat{I}\pm$. We divide our sample into six subsamples based on redshift and calculate the relative variation $\hat{I}”\hat{I}\pm /\hat{I}\pm$ for the individual subsamples. The calculated $\hat{I}”\hat{I}\pm /\hat{I}\pm$ values are consistent with zero within $1\ddot{I}ƒ$ at all redshifts, suggesting no time variation in $\hat{I}\pm$ above a level of $(1-2)\times 10^{-4}$ ($1\ddot{I}ƒ$) in the past 13.2 billion years. When the whole sample is combined, the constraint is improved to be $\hat{I}”\hat{I}\pm /\hat{I}\pm =(0.2\pm 0.7)\times 10^{-4}$. We further test the spatial variation in $\hat{I}\pm$ using four subsamples of galaxies in four different directions on the sky. The measured $\hat{I}”\hat{I}\pm /\hat{I}\pm$ values are consistent with zero at a $1\ddot{I}ƒ$ level of $\sim 2\times 10^{-4}$. While the constraints in this work are not as stringent as those from lower-redshift quasar absorption lines in previous studies, this work uses an independent tracer and provides the first constraints on $\hat{I}”\hat{I}\pm /\hat{I}\pm$ at the highest redshifts. With the growing number of emission-line galaxies from JWST, we expect to achieve stronger constraints in the future.

15 pages, 10 figures, accepted for publication in ApJ