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arXiv · 1611.05191

Constraint on a varying proton-to-electron mass ratio from H2 and HD absorption at z = 2.34

M. Daprà·M. van der Laan·M. T. Murphy·W. Ubachs
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Abstract

Molecular hydrogen absorption in the damped Lyman-alpha system at z = 2.34 towards quasar Q1232+082 is analyzed in order to derive a constraint on a possible temporal variation of the proton-to-electron mass ratio, mu, over cosmological timescales. Some 106 H2 and HD transitions, covering the range 3290-3726 Å, are analyzed with a comprehensive fitting technique, allowing for the inclusion of overlapping lines associated with hydrogen molecules, the atomic hydrogen lines in the Lyman-alpha forest as well as metal lines. The absorption model, based on the most recent and accurate rest wavelength for H2 and HD transitions, delivers a value of dmu/mu = (19 +/- 9 +/- 5)x 10^(-6). An attempt to correct the spectrum for possible long-range wavelength distortions is made and the uncertainty on the distortion correction is included in the total systematic uncertainty. The present result is an order of magnitude more stringent than a previous measurement from the analysis of this absorption system, based on a line-by-line comparison of only 12 prominent and isolated H2 absorption lines. This is consistent with other measurements of dmu/mu from 11 other absorption systems in showing a null variation of the proton-to-electron mass ratio over a look-back time of 11 Gyrs.

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M. Daprà, M. van der Laan, M. T. Murphy, W. Ubachs. 2016-11-18. Constraint on a varying proton-to-electron mass ratio from H2 and HD absorption at z = 2.34. https://doi.org/10.1093/mnras%2Fstw3003

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