COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses

IV. Models of prospective time-delay lenses

¹ Astronomy Unit, Queen Mary and Westfield College, University of London, London E1 4NS, UK
² Institüt für Theoretische Physik, Universität Zürich, Winterthurerstr. 190, 8057 Zürich, Switzerland
³ Laboratoire d'Astrophysique, École Polytechnique Fédérale de Lausanne (EPFL), Observatoire, 1290 Sauverny, Switzerland e-mail: frederic.courbin@epfl.ch
⁴ School of Physics and Astronomy, Cardiff University, 5 The Parade, Cardiff, CF24 3YB, UK

Received: 24 February 2005
Accepted: 16 January 2006

Abstract

Aims.To predict time delays for a sample of gravitationally lensed quasars and to evaluate the accuracy that can be realistically achieved on the value of H₀.

Methods.We consider 14 lensed quasars that are candidates for time-delay monitoring and model them in detail using pixelized lens models. For each system, we provide a mass map, arrival-time surface and the distribution of predicted time-delays in a concordance cosmology, assuming  Gyr ( in local units). Based on the predicted time-delays and on the observational circumstances, we rate each lens as “excellent” or “good” or “unpromising” for time-delay monitoring. Finally, we analyze simulated time delays for the 11 lens rated excellent or good, and show that H₀ can be recovered to a precision of 5%.

Results.In combination with COSMOGRAIL Paper I on the temporal sampling of lensed quasar light curves, the present work will help to optimize the strategy of the monitoring campaigns of lensed quasars.