The CO A-X System for Constraining Cosmological Drift of the Proton-Electron Mass Ratio

Abstract

The ${\text{A}}^1\Pi -{\text{X}}^1{\Sigma }^{+}$ band system of carbon monoxide, which has been detected in six highly redshifted galaxies ($z=1.6-2.7$), is identified as a novel probe method to search for possible variations of the proton-electron mass ratio ($\mu$) on cosmological time scales. Laboratory wavelengths of the spectral lines of the A-X ($v$,0) bands for $v=0-9$ have been determined at an accuracy of $\Delta \lambda /\lambda =1.5\times 10^{-7}$ through VUV Fourier-transform absorption spectroscopy, providing a comprehensive and accurate zero-redshift data set. For the (0,0) and (1,0) bands, two-photon Doppler-free laser spectroscopy has been applied at the $3\times 10^{-8}$ accuracy level, verifying the absorption data. Sensitivity coefficients $K_{\mu }$ for a varying $\mu$ have been calculated for the CO A-X bands, so that an operational method results to search for $\mu$-variation.

7 pages (main article), 3 figures, includes supplementary material

References in corpus (3)

• The First Positive Detection of Molecular Gas in a GRB Host Galaxy
• Strong Limit on a Variable Proton-to-Electron Mass Ratio from Molecules in the Distant Universe
• First constraint on cosmological variation of the proton-to-electron mass ratio from two independent telescopes

Cited by in corpus (3)

• Consistency tests of the stability of fundamental couplings and unification scenarios
• Cosmological Evolution of Fundamental Constants: From Theory to Experiment
• High-precision laser spectroscopy of the CO A${}^1\Pi$ - X${}^1{\Sigma }^{+}$ (2,0), (3,0) and (4,0) bands