Gravitational lenses with more than four images. I. Classification of caustics

Charles R. Keeton, Shude Mao, Hans J. Witt

Research output: Contribution to journalArticle

23 Scopus citations


We study the problem of gravitational lensing by an isothermal elliptical density galaxy in the presence of a tidal perturbation. When the perturbation is fairly strong and oriented near the galaxy's minor axis, the lens can produce image configurations with six or even eight highly magnified images lying approximately on a circle. We classify the caustic structures in the model and identify the range of models that can produce such lenses. Sextuple and octuple lenses are likely to be rare because they require special lens configurations, but a full calculation of the likelihood will have to include both the existence of lenses with multiple-lens galaxies and the strong magnification bias that affects sextuple and octuple lenses. At optical wavelengths, these lenses would probably appear as partial or complete Einstein rings, but at radio wavelengths, the individual images could probably be resolved.

Original languageEnglish (US)
Pages (from-to)697-707
Number of pages11
JournalAstrophysical Journal
Issue number2 PART 1
StatePublished - Jul 10 2000

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Distance scale
  • Gravitational lensing

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