An Optical Time-Delay for the Lensed BAL Quasar HE2149-2745
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.
Cite
@article{arxiv.astro-ph/0112225,
title = {An Optical Time-Delay for the Lensed BAL Quasar HE2149-2745},
author = {I. Burud and F. Courbin and P. Magain and C. Lidman and D. Hutsemekers and J. -P. Kneib and J. Hjorth and J. Brewer and E. Pompei and L. Germany and J. Pritchard and A. O. Jaunsen and G. Letawe and G. Meylan},
journal= {arXiv preprint arXiv:astro-ph/0112225},
year = {2008}
}
Comments
11 pages, accepted for publication in Astronomy & Astrophysics