A constraint on a varying proton--electron mass ratio 1.5 billion years after the Big Bang

TL;DR

This study uses high-resolution quasar spectra from 12.4 billion years ago to constrain possible variations in the proton-electron mass ratio, finding no significant deviation from current values.

Contribution

It provides one of the earliest constraints on the variation of the proton-electron mass ratio using molecular hydrogen absorption at high redshift.

Findings

No significant variation detected in μ over 12.4 billion years.

Achieved a limit of Δμ/μ = (-9.5 ± 5.4_stat ± 5.3_sys) × 10^{-6}.

Utilized high-resolution VLT spectra of quasar J1443+2724.

Abstract

A molecular hydrogen absorber at a lookback time of 12.4 billion years, corresponding to 10$\%$ of the age of the universe today, is analyzed to put a constraint on a varying proton--electron mass ratio, $\mu$. A high resolution spectrum of the J1443$+$2724 quasar, which was observed with the Very Large Telescope, is used to create an accurate model of 89 Lyman and Werner band transitions whose relative frequencies are sensitive to $\mu$, yielding a limit on the relative deviation from the current laboratory value of $\Delta\mu/\mu=(-9.5\pm5.4_{\textrm{stat}} \pm 5.3_{\textrm{sys}})\times 10^{-6}$.