Modelling long-range wavelength distortions in quasar absorption echelle spectra
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.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- June 2017
- DOI:
- 10.1093/mnras/stx381
- arXiv:
- arXiv:1701.03176
- Bibcode:
- 2017MNRAS.468.1568D
- Keywords:
-
- methods: data analysis;
- techniques: spectroscopic;
- quasars: absorption lines;
- cosmological parameters;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 8 pages, 7 figures, 3 tables