A portable modeler of lensed quasars

Prasenjit Saha, Liliya L.R. Williams

Research output: Contribution to journalArticlepeer-review

72 Scopus citations


We introduce and implement two novel ideas for modeling lensed quasars. The first is to require different lenses to agree about H 0. This means that some models for one lens can be ruled out by data on a different lens. We explain using two worked examples. One example models 1115+080 and 1608+656 (time-delay quadruple systems) and 1933+503 (a prospective time-delay system) all together, yielding time-delay predictions for the third lens and a 90% confidence estimate of H 0 -1 = 14.6 -1.7 +9.4 Gyr (H 0 = 67 -26 +9 km s -1 Mpc -1) assuming Ω M= 0.3 and ΩΛ = 0.7. The other example models the time-delay doubles 1520+530, 1600+434, 1830-211, and 2149-275, which gives H 0 -1 = 14.5 -1.5 +3.3 Gyr (H 0 = 67 -13 +8 km s -1 Mpc -1). Our second idea is to write the modeling software as a highly interactive Java applet, which can be used both for coarse-grained results inside a browser and for fine-grained results on a workstation. Several obstacles come up in trying to implement a numerically intensive method thus, but we overcome them.

Original languageEnglish (US)
Pages (from-to)2604-2616
Number of pages13
JournalAstronomical Journal
Issue number5 1781
StatePublished - May 2004


  • Gravitational lensing


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