EDP Sciences
Free Access
Issue
A&A
Volume 431, Number 1, February III 2005
Page(s) 103 - 109
Section Extragalactic astronomy
DOI https://doi.org/10.1051/0004-6361:20041432


A&A 431, 103-109 (2005)
DOI: 10.1051/0004-6361:20041432

An optical time delay for the double gravitational lens system FBQ 0951+2635

P. Jakobsson1, 2, J. Hjorth1, I. Burud3, G. Letawe4, C. Lidman5 and F. Courbin6

1  Niels Bohr Institute, Astronomical Observatory, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark
    e-mail: pallja@astro.ku.dk
2  Science Institute, University of Iceland, Dunhaga 3, 107 Reykjavík, Iceland
3  Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
4  Institut d'Astrophysique et de Géophysique, ULg, Allée du 6 Août 17, B5C, 4000 Sart Tilman (Liège), Belgium
5  European Southern Observatory, Casilla 19, Santiago, Chile
6  Laboratoire d'Astrophysique, École Polytechnique Fédérale de Lausanne, Observatoire, 1290 Chavannes-des-bois, Switzerland

(Received 8 June 2004 / Accepted 13 October 2004)

Abstract
We present optical R-band light curves of the double gravitationally lensed quasar FBQ 0951+2635 from observations obtained at the Nordic Optical Telescope between March 1999 and June 2001. A time delay of $\Delta \tau = 16$  $\pm$ 2 days (1 $\sigma$) is determined from the light curves. New constraints on the lensing geometry are provided by the position and ellipticity of the lensing galaxy. For a $(\Omega_{{\rm m}}, \Omega_{\Lambda})= (0.3, 0.7)$ cosmology, the time delay yields a Hubble parameter of H0 = 60+9-7  (random, $1 \sigma$$\pm
2$  (systematic) km s -1 Mpc -1 for a singular isothermal ellipsoid model and H0 = 63+9-7 (random, $1 \sigma$$\pm
1$  (systematic) km s -1 Mpc -1 for a constant mass-to-light ratio model. In both models, the errors are mainly due to the time-delay uncertainties. Non-parametric models yield H0 = 64+9-7  (random, $1 \sigma$$\pm 14$ (systematic) km s -1 Mpc -1.


Key words: gravitational lensing -- galaxies: quasars: individual: FBQ 0951+2635 -- cosmology: cosmological parameters



© ESO 2005

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.