Automated survey for gravitational lenses

Journal Article · Fri Jan 01 04:00:00 EST 1988 · Astron. J.; (United States)

DOI:https://doi.org/10.1086/114608· OSTI ID:5293147

Webster, R L; Hewett, P C; Irwin, M J

A new optical technique for surveying large numbers of quasars for evidence of gravitational lensing is described. Using the Automated Plate Measuring Facility at Cambridge to scan broadband direct and objective-prism plates, hundreds of thousands of objects can be examined to find quasar candidates with multiple image structures. The technique is effective for separations greater than about two arcseconds, and allows the probability of detecting a lens of specified magnitude, component magnitude difference, and component separation to be precisely calculated. Tables are given that quantify the probability of detection of multiply imaged quasars. When combined with the large numbers of quasars surveyed, specific theoretical predictions of the frequency of lensing can be directly tested. The results of a survey of 2500 quasars with magnitudes in the range of 17-20 covering 130 sq deg of sky are described. Significant new limits can be put on the numbers of gravitationally lensed quasars with wide image separations. These limits enable some calculations of the distribution of mass in the universe to be undertaken. In particular, limits can be placed on the numbers of cosmic strings in the universe. 21 references.

• Research Organization: Toronto Univ. (Canada); Cambridge Univ. (England)
• OSTI ID: 5293147
• Journal Information: Astron. J.; (United States), Journal Name: Astron. J.; (United States) Vol. 95; ISSN ANJOA
• Country of Publication: United States
• Language: English

Related Subjects

640106* -- Astrophysics & Cosmology-- Cosmology
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AUTOMATION
COMPOSITE MODELS
COSMIC RADIO SOURCES
DISTRIBUTION
EXTENDED PARTICLE MODEL
GRAVITATIONAL LENSES
IMAGES
LENSES
MASS DISTRIBUTION
MATHEMATICAL MODELS
PARTICLE MODELS
QUARK MODEL
QUASARS
RED SHIFT
SPATIAL DISTRIBUTION
STRING MODELS
SURVEYS
UNIVERSE