| Issue |
A&A
Volume 622, February 2019
|
|
|---|---|---|
| Article Number | A127 | |
| Number of page(s) | 4 | |
| Section | Atomic, molecular, and nuclear data | |
| DOI | https://doi.org/10.1051/0004-6361/201834782 | |
| Published online | 07 February 2019 | |
H2/HD molecular data for analysis of quasar spectra in search of varying constants⋆
1
Department of Physics and Astronomy, Vrije Universiteit, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
e-mail: w.m.g.ubachs@vu.nl
2
Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Melbourne, 3122 Victoria, Australia
3
Sorbonne Université, Observatoire de Paris, Université PSL, CNRS, LERMA, 92190
Meudon, France
Received:
5
December
2018
Accepted:
24
December
2018
Context. Absorption lines of H2 and HD molecules observed at high redshift in the line of sight towards quasars are a test ground to search for variation of the proton-to-electron mass ratio μ. For this purpose, results from astronomical observations are compared with a compilation of molecular data of the highest accuracy, obtained in laboratory studies as well as in first-principles calculations.
Aims. A comprehensive line list is compiled for H2 and HD absorption lines in the Lyman (B1Σu+ − X1Σg+) and Werner (C1Πu − X1Σg+) band systems up to the Lyman cutoff at 912 Å. Molecular parameters listed for each line i are the transition wavelength λi, the line oscillator strength fi, the radiative damping parameter of the excited state Γi, and the sensitivity coefficient Ki for a variation of the proton-to-electron mass ratio.
Methods. The transition wavelengths λi for the H2 and HD molecules are determined by a variety of advanced high-precision spectroscopic experiments involving narrowband vacuum ultraviolet lasers, Fourier-transform spectrometers, and synchrotron radiation sources. Results for the line oscillator strengths fi, damping parameters Γi, and sensitivity coefficients Ki are obtained in theoretical quantum chemical calculations.
Results. A new list of molecular data is compiled for future analyses of cold clouds of hydrogen absorbers, specifically for studies of μ-variation from quasar data. The list is applied in a refit of quasar absorption spectra of B0642–5038 and J1237+0647 yielding constraints on a variation of the proton-to-electron mass ratio Δμ/μ consistent with previous analyses.
Key words: molecular data
Tables 1–3 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/622/A127
© ESO 2019
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