EDP Sciences
Free access
Volume 466, Number 3, May II 2007
Page(s) 1077 - 1082
Section Stellar structure and evolution
DOI http://dx.doi.org/10.1051/0004-6361:20066064

A&A 466, 1077-1082 (2007)
DOI: 10.1051/0004-6361:20066064

A new measure of $\mathsf{\Delta\alpha/\alpha}$ at redshift $\mathsf{z = 1.84}$ from very high resolution spectra of Q 1101-264

S. A. Levshakov1, P. Molaro2, 3, S. Lopez4, S. D'Odorico5, M. Centurión2, P. Bonifacio2, 3, I. I. Agafonova1, and D. Reimers1

1  Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
    e-mail: lev@astro.ioffe.rssi.ru
2  Osservatorio Astronomico di Trieste, via G. B. Tiepolo 11, 34131 Trieste, Italy
3  Observatoire de Paris, 61 avenue de l'Observatoire, 75014 Paris, France
4  Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile
5  European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany

(Received 19 July 2006 / Accepted 26 February 2007)

Aims.We probe the evolution of the fine-structure constant $\alpha$ with cosmic time.
Methods.Accurate positions of the $\ion{Fe}{ii}$ lines $\lambda1608$, $\lambda2382$, and $\lambda2600$ are measured in the $z_{\rm abs}$ = 1.84 absorption system from a high-resolution (FWHM ~ 3.8 km s-1) and high signal-to-noise (S/N $\ga$ 100) spectrum of the quasar  Q 1101-264 ( $z_{\rm em}$ = 2.15, V = 16.0), integrated for 15.4 h. The Single Ion Differential $\alpha$ Measurement (SIDAM) procedure and the $\Delta \chi^2$ method are used to set constraints on $\Delta\alpha/\alpha$.
Results.We have found a relative radial velocity shift between the $\lambda1608$ and $\lambda\lambda2382,2600$ lines of $\Delta v = -180$ $\pm$ 85 m s-1 (both random and systematic errors are included), which, if real, would correspond to $\Delta\alpha/\alpha$ = $(5.4\pm2.5)$ $\times$ 10-6 ($1\sigma$ C.L.). Considering the strong implications of a such variability, additional observations with comparable accuracy at redshift $z \sim 1.8$ are required to confirm this result.

Key words: cosmology: observations -- line: profiles -- galaxies: quasars: absorption lines -- galaxies: quasars: individual: Q 1101-264

© ESO 2007