Gravitational lensing by an ensemble of isothermal galaxies

Journal Article · Mon Jun 01 04:00:00 EDT 1987 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/165252· OSTI ID:5954629

Katz, N; Paczynski, B

Calculation of 28,000 models of gravitational lensing of a distant quasar by an ensemble of randomly placed galaxies, each having a singular isothermal mass distribuiton, is reported. The average surface mass density was 0.2 of the critical value in all models. It is found that the surface mass density averaged over the area of the smallest circle that encompasses the multiple images is 0.82, only slightly smaller than expected from a simple analytical model of Turner et al. (1984). The probability of getting multiple images is also as large as expected analytically. Gravitational lensing is dominated by the matter in the beam; i.e., by the beam convergence. The cases where the multiple imaging is due to asymmetry in mass distribution (i.e., due to shear) are very rare. Therefore, the observed gravitational-lens candidates for which no lensing object has been detected between the images cannot be a result of asymmetric mass distribution outside the images, at least in a model with randomly distributed galaxies. A surprisingly large number of large separations between the multiple images is found: up to 25 percent of multiple images have their angular separation 2 to 4 times larger than expected in a simple analytical model. 11 references.

• Research Organization: Princeton Univ. Observatory, NJ
• OSTI ID: 5954629
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 317; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640106* -- Astrophysics & Cosmology-- Cosmology
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COSMIC RADIO SOURCES
DENSITY
DISTRIBUTION
GALAXY CLUSTERS
GRAVITATIONAL LENSES
IMAGES
ISOTHERMAL PROCESSES
LENSES
MASS DISTRIBUTION
MATHEMATICAL MODELS
MORPHOLOGY
PHYSICAL PROPERTIES
QUASARS
SPATIAL DISTRIBUTION