EDP Sciences
Free access
Volume 449, Number 3, April III 2006
Page(s) 879 - 889
Section Cosmology (including clusters of galaxies)
DOI http://dx.doi.org/10.1051/0004-6361:20053827
A&A 449, 879-889 (2006)
DOI: 10.1051/0004-6361:20053827

Most precise single redshift bound to $\mathsf{\Delta\alpha/\alpha}$

S. A. Levshakov1, M. Centurión2, P. Molaro2, 3, S. D'Odorico4, D. Reimers5, R. Quast5 and M. Pollmann5

1  Department of Theoretical Astrophysics, Ioffe Physico-Technical Institute, 194021 St. Petersburg, Russia
    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  European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany
5  Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany

(Received 14 July 2005 / Accepted 21 November 2005 )

Aims.Verification the theoretical prediction of oscillation of the fine-structure constant $\alpha\,\, (\equiv$ $e^2/\hbar c)$ over cosmic time requires high precision $\Delta\alpha/\alpha\,$ measurements at individual redshifts. In earlier studies the mean $\Delta\alpha/\alpha\,$ values averaged over wide redshift intervals were usually reported. This requirement can be met using the single ion differential $\alpha$ measurement (SIDAM) procedure. We apply SIDAM to the $\ion{Fe}{ii}$ lines associated with the damped Ly$\alpha$ system observed at $z_{\rm abs}$ = 1.15 in the spectrum of HE 0515-4414 .
Methods.The spectrum was obtained by means of the UV-Visual Echelle Spectrograph (UVES) at the ESO Very Large Telescope (VLT).
Results.The weighted mean $\langle \Delta\alpha/\alpha \rangle$ calculated using carefully selected 34  $\ion{Fe}{ii}$ pairs $\{\lambda 1608,X\}$ ( X = 2344, 2374, and 2586 Å) is $\langle \Delta\alpha/\alpha \rangle =
(-0.07\pm0.84)\times10^{-6}$ ($1\sigma$ C.L.). The precision of this estimate improves by a factor of 2 the previous one reported for the same system. The obtained result represents an absolute improvement with respect to what has been done in the measurements of $\Delta\alpha/\alpha\,$.

Key words: cosmology: observations -- quasars: absorption lines

SIMBAD Objects

© ESO 2006