Robust limit on a varying proton-to-electron mass ratio from a single H2 system

TL;DR

This study provides a robust limit on the possible variation of the proton-to-electron mass ratio using independent observations of molecular hydrogen in a distant quasar, addressing previous controversies with new methods.

Contribution

It introduces alternative data analysis approaches and systematic correction methods for more accurate measurements of mu variation from QSO spectra.

Findings

Estimated change in mu: 15 +/- (9_stat + 6_sys) x 10^{-6} at z=3.025

Achieved a measurement accuracy limit of about 300 m/s considering systematics

Presented new methods for systematic correction and spectral analysis in quasar observations.

Abstract

The variation of the dimensionless fundamental physical constant mu=m_p/m_e can be checked through observation of Lyman and Werner lines of molecular hydrogen in the spectra of distant QSOs. Our intention is to asses the accuracy of the investigation concerning a possible variation of mu and to provide more robust results for QSO 0347-383. The goal in mind is to resolve the current controversy on variation of mu and devise explanations for the different findings. We achieve this not by another single result but by providing alternative approaches to the problem. An analysis based on independent data sets of QSO 0347-383 is put forward and new approaches for some of the steps involved in the data analysis are introduced. We analyse two independent sets of observations of the same absorption system and for the first time we apply corrections for the observed offsets between discrete spectra Drawing on two independent observations of a single absorption system in QSO 0347-383 our detailed analysis yields dmu/mu = 15 +/- (9_stat + 6_sys) x 10^{-6} at z_abs=3.025. Based on the overall goodness-of-fit we estimate the limit of accuracy to about 300 m/s, consisting of roughly 180 m/s due to the uncertainty of the fit and about 120 m/s allocated to systematics This work presents alternative approaches to handle systematics and introduces methods required for precision analysis of QSO spectra available in the near future.