Modelling long-range wavelength distortions in quasar absorption echelle spectra. Issue 2 (14th February 2017)

• Record Type: Journal Article
• Authors: Dumont, V.; Webb, J. K.
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 468:Issue 2(2017)
• Page Start: 1568
• Page End: 1574
• Publication Date: 2017-02-14
• Subjects: methods: data analysis -- techniques: spectroscopic -- quasars: absorption lines -- cosmological parameters; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stx381
• Languages: English
• ISSNs: 0035-8711

Abstract

Abstract: Spectra observed with the Ultraviolet and Visual Echelle Spectrograph on the European Southern Observatory's VLT exhibit long-range wavelength distortions. These distortions impose a systematic error on high-precision measurements of the fine-structure constant, α, derived from intervening quasar absorption systems. If the distortion is modelled using a model that is too simplistic, the resulting bias in Δα/α away from the true value can be larger than the statistical uncertainty on the α measurement. If the effect is ignored altogether, the same is true. If the effect is modelled properly, accounting for the way in which final spectra are generally formed from the co-addition of exposures made at several different instrumental settings, the effect can be accurately removed and the correct Δα/α recovered.