2002/05/28 by Tehani K. Finch, Lisa P. Carlivati, Joshua N. Winn +1 · 1 citation
Engineering · Physics and Astronomy · #Adaptive optics and wavefront sensing #Astronomical Observations and Instrumentation #Astrophysics #Focal length #Galaxy #Gravitational lens #Gravitational lensing formalism #Lens (geology) #Magnification #Optics #Physics #Simple lens #Stellar, planetary, and galactic studies #Strong gravitational lensing #Weak gravitational lensing #astro-ph
paper · pdf · doi:10.1086/342163
published as Astrophys.J. 577 (2002) 51-56 · 15pp 3 figs, accepted for publication in ApJ
arxiv created 2002/05/28 · openalex publication_date 2002/09/20 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We derive an analytic expression for the mean magnification due to strong gravitational lensing, using a simple lens model: a singular isothermal sphere embedded in an external shear field. We compute separate expressions for two-image and four-image lensing. For four-image lensing, the mean magnification takes a particularly simple form: ⟨μ 4 ⟩ = 3.6/ , where γ is the external shear. We compare our analytic results with a numerical evaluation of the full magnification distribution. The results can be used to understand the magnification bias that favors the discovery of four-image systems over two-image systems in flux-limited lens surveys.