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

P. Jakobsson·J. Hjorth·I. Burud·G. Letawe·C. Lidman·F. Courbin
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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 16 +/- 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_m, Omega_Lambda) = (0.3, 0.7) cosmology, the time delay yields a Hubble parameter of H_0 = 60^{+9}_{-7} (random, 1 sigma) +/- 2 (systematic) km/s/Mpc for a singular isothermal ellipsoid model and H_0 = 63^{+9}_{-7} (random, 1 sigma) +/- 1 (systematic) km/s/Mpc 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 H_0 = 64^{+9}_{-7} (random, 1 sigma) +/- 14 (systematic) km/s/Mpc.

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P. Jakobsson, J. Hjorth, I. Burud, G. Letawe, C. Lidman, F. Courbin. 2004-09-17. An optical time delay for the double gravitational lens system FBQ 0951+2635. https://doi.org/10.1051/0004-6361%3A20041432

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