Fermat's principle, caustics, and the classification of gravitational lens images

Journal Article · Sat Nov 01 04:00:00 EST 1986 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/164709· OSTI ID:6443179

Blandford, R; Narayan, R

A scalar description of gravitational lensing based on Fermat's principle is described. The lensing mass is assumed to be confined to a single plane between the source and the observer, and a time delay is associated with each position in the sky of a potential image. The extrema of this time surface then give the true positions of the images. A topological classification of image configurations is presented, and the results are generalized to cases of three and five-image lensing geometries. A computer-graphical approach to the study of lensing by model galaxies and clusters is described, and the design of a simple optical apparatus which could be used for fast modelling of image geometries is outlined. The connection between the Fermat approach and the classical theory of caustics and the more recent general theory of catastrophies is developed. The extension of the results to multiple scattering is considered. 42 references.

• Research Organization: California Institute of Technology, Pasadena
• OSTI ID: 6443179
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 310; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640105 -- Astrophysics & Cosmology-- Galaxies
657003* -- Theoretical & Mathematical Physics-- Relativity & Gravitation
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CLASSIFICATION
CONFIGURATION
COSMIC RADIO SOURCES
ELLIPTICAL CONFIGURATION
FERMAT PRINCIPLE
GALAXIES
GALAXY CLUSTERS
GRAVITATIONAL LENSES
LENSES
MASS
NONLUMINOUS MATTER
QUASARS