CONSTRAINT ON A COSMOLOGICAL VARIATION IN THE PROTON-TO-ELECTRON MASS RATIO FROM ELECTRONIC CO ABSORPTION

Carbon monoxide (CO) absorption in the sub-damped Lyα absorber at redshift toward the background quasar SDSS J123714.60+064759.5 (J1237+0647) was investigated for the first time in order to search for a possible variation of the proton-to-electron mass ratio, μ, over a cosmological timescale. The observations were performed with the Very Large Telescope/Ultraviolet and Visual Echelle Spectrograph with a signal-to-noise ratio of 40 per 2.5 km s−1...