Open AccessLens modelling and estimate of H 0 in quadruply lensed systems
Author(s) -
Tortora C.,
Piedipalumbo E.,
Cardone V. F.
Publication year - 2004
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2004.08160.x
Subject(s) - physics , hubble's law , gravitational lens , quasar , lens (geology) , galaxy , separable space , constant (computer programming) , cosmology , astrophysics , optics , redshift , mathematical analysis , mathematics , computer science , programming language
We present a numerical method to estimate the lensing parameters and the Hubble constant H 0 from quadruply imaged gravitational lens systems. The lens galaxy is modelled using both separable deflection potentials and constant mass‐to‐light ratio profiles, while possible external perturbations have been taken into account by introducing an external shear. The model parameters are recovered by inverting the lens and the time‐delay ratio equations and imposing a set of physically motivated selection criteria. We investigate correlations among the model parameters and the Hubble constant. Finally, we apply the codes to the real lensed quasars PG 1115+080 and RX J0911+0551, and combine the results from these two systems to get H 0 = 56 ± 23 km s −1 Mpc −1 . In addition, we are able to fit to the single systems a general elliptical potential with a non‐fixed angular part, and then we model the two‐lens systems with the same potential and a shared H 0 : in this last case, we estimate H 0 = 49 +6 −11 km s −1 Mpc −1 .