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arXiv · 1701.03176

Modeling long-range wavelength distortions in quasar absorption echelle spectra

Vincent Dumont·John K. Webb
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Abstract

Spectra observed with the Ultraviolet and Visual Echelle Spectrograph (UVES) 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, $\alpha$, derived from intervening quasar absorption systems. If the distortion is modelled using a model that is too simplistic, the resulting bias in $\Delta\alpha/\alpha$ away from the true value can be larger than the statistical uncertainty on the $\alpha$ 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 $\Delta\alpha/\alpha$ recovered.

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Vincent Dumont, John K. Webb. 2017-01-11. Modeling long-range wavelength distortions in quasar absorption echelle spectra. https://doi.org/10.1093/mnras%2Fstx381

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