EDP Sciences
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Volume 415, Number 2, February IV 2004
Page(s) L7 - L11
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:20040013

A&A 415, L7-L11 (2004)
DOI: 10.1051/0004-6361:20040013


Probing the variability of the fine-structure constant with the VLT/UVES

R. Quast1, D. Reimers1 and S. A. Levshakov2

1  Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
2  Department of Theoretical Astrophysics, Ioffe Physico-Technical Institute, 194021 St. Petersburg, Russia

(Received 11 November 2003 / Accepted 22 December 2003 )

We assess the cosmological variability of the fine-structure constant $\alpha$ from the analysis of an ensemble of $\ion{Fe}{ii}$  $\lambda1608$, $\lambda2344$, $\lambda2374$, $\lambda2383$, $\lambda2587$, and $\lambda2600$ absorption lines at the redshift z=1.15 toward the QSO HE 0515-4414 by means of the standard many-multiplet (MM) technique and its revision based on linear regression (RMM). This is the first time the MM technique is applied to exceptional high-resolution and high signal-to-noise QSO spectra recorded with the UV-Visual Echelle Spectrograph (UVES) at the ESO Very Large Telescope (VLT). Our analysis results in $\langle\Delta\alpha/\alpha\rangle_\mathrm{MM}=(0.1\pm1.7)
\times10^{-6}$ and $\langle\Delta\alpha/\alpha\rangle_\mathrm{RMM}=(-0.4
\pm1.9\pm2.7_\mathrm{sys})\times10^{-6}$ , which are the most stringent bounds hitherto infered from an individual QSO absorption system. Our results support the null hypothesis $\langle\Delta\alpha/\alpha\rangle=0$ at a significance level of 91 percent, whereas the support for the result $\langle\Delta\alpha/\alpha\rangle=-5.7\times10^{-6}$ presented in former MM studies is 12 percent.

Key words: cosmology: observations -- quasars: absorption lines -- quasars: individual: HE 0515-4414

Offprint request: R. Quast, rquast@hs.uni-hamburg.de

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