Gravitational lensing frequencies: Galaxy cross-sections and selection effects

Masataka Fukugita, Edwin L. Turner

Research output: Contribution to journalArticle

190 Scopus citations

Abstract

In order to allow more realistic predictions of multiple image galaxy-quasar lensing frequencies, we consider in detail four issues: the best currently available data on the galaxy velocity dispersion distribution, the effects of finite core radii potential ellipticity on lensing cross-sections, the predicted distribution of lens image separations compared to observational angular resolutions, and the preferential inclusion ('amplification bias') of lens systems in flux limited samples. We find (1) that the singular isothermal sphere (SIS) lensing parameter F = 0.047 ± 0.019 with almost 90 per cent contributed by E and SO galaxies, (2) that observed E and SO core radii are remarkably small giving a factor of ≲ 2 reduction in total lensing cross-sections, (3) that 50 per cent of galaxy-quasar lenses have image separations bigger than ∼ 1.3 arcsec (25 per cent, > 2 arcsec) and should be relatively easily detected, and (4) that amplification bias factors are large (few to tens) and must be carefully taken into account. Including all of the above considerations, we conclude that flat Universe models excessively dominated by the cosmological constant are not favoured by the small observed galaxy-quasar lensing rate. Models with a dimensionless cosmological constant λ0 =0.9 may be marginally consistent with the available data; all λ0 =0 models give a good fit.

Original languageEnglish (US)
Pages (from-to)99-106
Number of pages8
JournalMonthly Notices of the Royal Astronomical Society
Volume253
Issue number1
DOIs
StatePublished - Nov 1 1991

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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