An Optical Time-Delay for the Lensed BAL Quasar HE2149-2745

I. Burud; F. Courbin; P. Magain; C. Lidman; D. Hutsemekers; J. -P. Kneib; J. Hjorth; J. Brewer; E. Pompei; L. Germany; J. Pritchard; A. O. Jaunsen; G. Letawe; G. Meylan

doi:10.1051/0004-6361:20011731

arXiv · astro-ph/0112225

An Optical Time-Delay for the Lensed BAL Quasar HE2149-2745

I. Burud·F. Courbin·P. Magain·C. Lidman·D. Hutsemekers·J. -P. Kneib·J. Hjorth·J. Brewer·E. Pompei·L. Germany·J. Pritchard·A. O. Jaunsen·G. Letawe·G. Meylan

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Abstract

We present optical V and i-band light curves of the gravitationally lensed BAL quasar HE2149-2745. The data, obtained with the 1.5m Danish Telescope (ESO-La Silla) between October 1998 and December 2000, are the first from a long-term project aimed at monitoring selected lensed quasars in the Southern Hemisphere. A time delay of 103+/-12 days is determined from the light curves. In addition, VLT/FORS1 spectra of HE2149-2745 are deconvolved in order to obtain the spectrum of the faint lensing galaxy, free of any contamination by the bright nearby two quasar images. By cross-correlating the spectrum with galaxy-templates we obtain a tentative redshift estimate of z=0.495+/-0.01. Adopting this redshift, a Omega=0.3, Lambda=0.7 cosmology, and a chosen analytical lens model, our time-delay measurement yields a Hubble constant of H_0=66+/-8 km/s/Mpc with an estimated systematic error of +/-3 km/s/Mpc. Using non-parametric models yields H_0=65+/-8 km/s/Mpc and confirms that the lens exhibits a very dense/concentrated mass profile.

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I. Burud, F. Courbin, P. Magain, C. Lidman, D. Hutsemekers, J. -P. Kneib, J. Hjorth, J. Brewer, E. Pompei, L. Germany, J. Pritchard, A. O. Jaunsen, G. Letawe, G. Meylan. 2001-12-10. An Optical Time-Delay for the Lensed BAL Quasar HE2149-2745. https://doi.org/10.1051/0004-6361%3A20011731

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