Gravitational lensing model degeneracies: Is steepness all-important?

Prasenjit Saha, Liliya L.R. Williams

Research output: Contribution to journalArticlepeer-review

46 Scopus citations


In gravitational leasing, steeper mass profiles genetically produce longer time delays but smaller magnifications, without necessarily changing the image positions or magnification ratios between different images. This is well known. We find in this paper, however, that even if steepness is fixed, time delays can still have significant model dependence, which we attribute to shape-modeling degeneracies. This conclusion follows from numerical experiments with models of 35 galaxy lenses. We suggest that varying and twisting ellipticities, features that are explored by pixelated lens models but not, so far, by parametric models, has an important effect on time delays.

Original languageEnglish (US)
Pages (from-to)936-941
Number of pages6
JournalAstrophysical Journal
Issue number2 I
StatePublished - Dec 20 2006


  • Gravitational lensing


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