H. Rahmani, M. Wendt, R. Srianand, P. Noterdaeme, P. Petitjean, P. Molaro, J. B. Whitmore, M. T. Murphy, M. Centuriˇn, H. Fathivavsari, S. D'Odorico, T. M. Evans, S. A. Levshakov, S. Lopez, C. J. A. P. Martins, D. Reimers, G. Vladilo
We present an accurate analysis of the H2 absorption lines from the zabs ~ 2.4018 damped Lyasystem towards HE 0027-1836 observed with the Very Large Telescope Ultraviolet and Visual Echelle Spectrograph (VLT/UVES) as a part of the European Southern Observatory Large Programme ”The UVES large programme for testing fundamental physics” to constrain the variation of proton-to-electronmass ratio, µ = mp/me.We perform cross-correlation analysis between 19 individual exposures taken over three years and the combined spectrum to check the wavelength calibration stability. We notice the presence of a possible wavelength dependent velocity drift especially in the data taken in 2012. We use available asteroids spectra taken with UVES close to our observations to confirm and quantify this effect. We consider single and two component Voigt profiles to model the observed H2 absorption profiles. We use both linear regression analysis and Voigt profile fitting where Δµ/µ is explicitly considered as an additional fitting parameter. The two component model is marginally favored by the statistical indicators and we get Δµ/µ = -2.5 ± 8.1stat ± 6.2sys ppm. When we apply the correction to the wavelength dependent velocity drift we find Δµ/µ = -7.6 ± 8.1stat ± 6.3sys ppm. It will be important to check the extent to which the velocity drift we notice in this study is present in UVES data used for previous Δµ/µ measurements.
galaxies: quasar: absorption line – galaxies: intergalactic medium – quasar: individual: HE 0027-1836
Based on data obtained with UVES at the Very Large Telescope of the European Southern Observatory (Prgm. ID 185.A-0745)
Monthly Notices of the Royal Astronomical Society
Volume 435, Issue 1, Page 861