Accurate laboratory ultraviolet wavelengths for quasar absorption-line constraints on varying fundamental constants
(2006) In Monthly Notices of the Royal Astronomical Society 370(1). p.444-452- Abstract
- The most precise method of investigating possible space-time variations of the fine-structure constant, alpha equivalent to (1/hc)(e(2)/4 pi epsilon(0)), using high-redshift quasar absorption lines is the many-multiplet (MM) method. For reliable results this method requires very accurate relative laboratory wavelengths for a number of UV resonance transitions from several different ionic species. For this purpose laboratory wavelengths and wavenumbers of 23 UV lines from Mg I, Mg II, Ti II, Cr II, Mn II, Fe II and Zn II have been measured using high-resolution Fourier transform (FT) spectrometry. The spectra of the different ions (except for one Fe II line, one Mg I line and the Ti II lines) are all measured simultaneously in the same FT... (More)
- The most precise method of investigating possible space-time variations of the fine-structure constant, alpha equivalent to (1/hc)(e(2)/4 pi epsilon(0)), using high-redshift quasar absorption lines is the many-multiplet (MM) method. For reliable results this method requires very accurate relative laboratory wavelengths for a number of UV resonance transitions from several different ionic species. For this purpose laboratory wavelengths and wavenumbers of 23 UV lines from Mg I, Mg II, Ti II, Cr II, Mn II, Fe II and Zn II have been measured using high-resolution Fourier transform (FT) spectrometry. The spectra of the different ions (except for one Fe II line, one Mg I line and the Ti II lines) are all measured simultaneously in the same FT spectrometry recording by using a composite hollow cathode as a light source. This decreases the relative uncertainties of all the wavelengths. In addition to any measurement uncertainty, the wavelength uncertainty is determined by that of the Ar II calibration lines, by possible pressure shifts and by illumination effects. The absolute wavenumbers have uncertainties of typically +/- 0.001 -+/- 0.002 cm(-1) (Delta lambda approximate to 0.06-0.1 m angstrom at 2500 angstrom), while the relative wavenumbers for strong, symmetric lines in the same spectral recording have uncertainties of +/- 0.0005 cm(-1) (Delta lambda approximate to 0.03 m angstrom at 2500 angstrom) or better, depending mostly on uncertainties in the line-fitting procedure. This high relative precision greatly reduces the potential for systematic effects in the MM method, while the new Ti II measurements now allow these transitions to be used in MM analyses. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/401303
- author
- Aldenius, Maria LU ; Johansson, Sveneric LU and Murphy, M. T.
- organization
- publishing date
- 2006
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- quasars : absorption lines, spectroscopic, techniques :, methods : laboratory, atomic data, line : profiles, ultraviolet : general
- in
- Monthly Notices of the Royal Astronomical Society
- volume
- 370
- issue
- 1
- pages
- 444 - 452
- publisher
- Oxford University Press
- external identifiers
-
- wos:000239116800037
- scopus:33746089121
- ISSN
- 1365-2966
- DOI
- 10.1111/j.1365-2966.2006.10491.x
- language
- English
- LU publication?
- yes
- id
- dd52c1e3-06b0-4b79-9793-ebc7e8620ac3 (old id 401303)
- date added to LUP
- 2016-04-01 11:54:51
- date last changed
- 2024-02-23 12:19:45
@article{dd52c1e3-06b0-4b79-9793-ebc7e8620ac3, abstract = {{The most precise method of investigating possible space-time variations of the fine-structure constant, alpha equivalent to (1/hc)(e(2)/4 pi epsilon(0)), using high-redshift quasar absorption lines is the many-multiplet (MM) method. For reliable results this method requires very accurate relative laboratory wavelengths for a number of UV resonance transitions from several different ionic species. For this purpose laboratory wavelengths and wavenumbers of 23 UV lines from Mg I, Mg II, Ti II, Cr II, Mn II, Fe II and Zn II have been measured using high-resolution Fourier transform (FT) spectrometry. The spectra of the different ions (except for one Fe II line, one Mg I line and the Ti II lines) are all measured simultaneously in the same FT spectrometry recording by using a composite hollow cathode as a light source. This decreases the relative uncertainties of all the wavelengths. In addition to any measurement uncertainty, the wavelength uncertainty is determined by that of the Ar II calibration lines, by possible pressure shifts and by illumination effects. The absolute wavenumbers have uncertainties of typically +/- 0.001 -+/- 0.002 cm(-1) (Delta lambda approximate to 0.06-0.1 m angstrom at 2500 angstrom), while the relative wavenumbers for strong, symmetric lines in the same spectral recording have uncertainties of +/- 0.0005 cm(-1) (Delta lambda approximate to 0.03 m angstrom at 2500 angstrom) or better, depending mostly on uncertainties in the line-fitting procedure. This high relative precision greatly reduces the potential for systematic effects in the MM method, while the new Ti II measurements now allow these transitions to be used in MM analyses.}}, author = {{Aldenius, Maria and Johansson, Sveneric and Murphy, M. T.}}, issn = {{1365-2966}}, keywords = {{quasars : absorption lines; spectroscopic; techniques :; methods : laboratory; atomic data; line : profiles; ultraviolet : general}}, language = {{eng}}, number = {{1}}, pages = {{444--452}}, publisher = {{Oxford University Press}}, series = {{Monthly Notices of the Royal Astronomical Society}}, title = {{Accurate laboratory ultraviolet wavelengths for quasar absorption-line constraints on varying fundamental constants}}, url = {{http://dx.doi.org/10.1111/j.1365-2966.2006.10491.x}}, doi = {{10.1111/j.1365-2966.2006.10491.x}}, volume = {{370}}, year = {{2006}}, }