EDP Sciences
Free access
Volume 379, Number 1, November III 2001
Page(s) 72 - 81
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20011225

A&A 379, 72-81 (2001)
DOI: 10.1051/0004-6361:20011225

Gravitational lensing potential reconstruction in quadruply imaged systems

V. F. Cardone1, S. Capozziello1, V. Re1 and E. Piedipalumbo2

1  Dipartimento di Fisica "E.R. Caianiello" , Università di Salerno and INFN, Sezione di Napoli, Gruppo Collegato di Salerno, Via S. Allende, 84081 Baronissi (Salerno), Italy
2  Dipartimento di Scienze Fisiche, Università di Napoli and INFN, Sezione di Napoli, Complesso Universitario di Monte S. Angelo, Via Cinthia, Edificio N, 80126 Napoli, Italy

(Receveid 15 February 2001 / Accepted 29 August 2001)

We develop a semi-analytical method to reconstruct the lensing potential in quadruply imaged gravitational lens systems. Assuming that the potential belongs to a broad class of boxy non-elliptical models, we show how it is possible to write down a system of equations which can be numerically solved to recover the potential parameters directly from image positions and using physical constraints. We also describe a code developed to search for solutions of the system previously found and test it on simulated cases. Finally, we apply the method to the quadruple lens PG 1115+080 which allows us to get also an estimate of the Hubble constant H0 from the measured time delay as $H_0 = 56_{-11}^{+12} {\rm km s^{-1} Mpc^{-1}}$.

Key words: gravitational lensing -- cosmology: distance scale -- galaxies: structure -- quasars: individual: PG 1115+080

Offprint request: V. F. Cardone, Vincenzo.Cardone@na.infn.it

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