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Title: Analysis of molecular hydrogen absorption toward QSO B0642–5038 for a varying proton-to-electron mass ratio

Rovibronic molecular hydrogen (H{sub 2}) transitions at redshift z {sub abs} ≅ 2.659 toward the background quasar B0642–5038 are examined for a possible cosmological variation in the proton-to-electron mass ratio μ. We utilize an archival spectrum from the Very Large Telescope/Ultraviolet and Visual Echelle Spectrograph (UVES) with a signal-to-noise ratio of ∼35 per 2.5 km s{sup –1} pixel at the observed H{sub 2} wavelengths (335-410 nm). Some 111 H{sub 2} transitions in the Lyman and Werner bands have been identified in the damped Lyα system for which a kinetic gas temperature of ∼84 K and a molecular fraction log f = –2.18 ± 0.08 are determined. The H{sub 2} absorption lines are included in a comprehensive fitting method, which allows us to extract a constraint on a variation of the proton-electron mass ratio Δμ/μ from all transitions at once. We obtain Δμ/μ = (17.1 ± 4.5{sub stat} ± 3.7{sub sys}) × 10{sup –6}. However, we find evidence that this measurement has been affected by wavelength miscalibration errors recently identified in UVES. A correction based on observations of objects with solar-like spectra gives a smaller Δμ/μ value and contributes to a larger systematic uncertainty: Δμ/μ = (12.7 ± 4.5{sub stat} ±more » 4.2{sub sys}) × 10{sup –6}.« less
Authors:
;  [1] ; ;  [2]
  1. Department of Physics and Astronomy, VU University Amsterdam, De Boelelaan 1081, 1081-HV Amsterdam (Netherlands)
  2. Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Victoria 3122 (Australia)
Publication Date:
OSTI Identifier:
22348061
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 782; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; CORRECTIONS; DATA; ELECTRONS; GALAXIES; HYDROGEN; LIMITING VALUES; MASS; MOLECULES; PROTONS; QUASARS; RED SHIFT; SIGNAL-TO-NOISE RATIO; SPECTRA; TELESCOPES; ULTRAVIOLET RADIATION; WAVELENGTHS