1999/06/30 by Rennan Barkana, Abraham Loeb · 7 citations
Physics and Astronomy · #Adaptive optics and wavefront sensing #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Dark matter #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy formation and evolution #Gravitational lens #Physics #Quasar #Redshift #Weak gravitational lensing #astro-ph
paper · pdf · doi:10.1086/308503
27 pages, 8 PostScript figures (of which two are new), revised version accepted for ApJ
arxiv created 1999/09/23 · openalex publication_date 2000/03/10 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Direct observations of the first generation of luminous objects will likely become feasible over the next decade. The advent of the Next Generation Space Telescope ( NGST ) will allow imaging of numerous galaxies and mini-quasars at redshifts z ≳ 5. We apply semianalytic models of structure formation to estimate the rate of multiple imaging of these sources by intervening gravitational lenses. Popular cold dark matter (CDM) models for galaxy formation yield a lensing optical depth of ∼1% for sources at z ∼ 10. The expected slope of the luminosity function of the early sources implies an additional magnification bias of ∼5, bringing the fraction of lensed sources at z = 10 to ∼5%. We estimate the angular size distribution of high-redshift disk galaxies and find that most of them are more extended than the resolution limit of NGST , ∼0 06. We also show that there is only a modest redshift evolution in the observed mean surface brightness of galaxies at z ≳ 2. The expected increase by 1-2 orders of magnitude in the number of resolved sources on the sky, due to observations with NGST , will dramatically improve upon the statistical significance of existing weak-lensing measurements. We show that despite this increase in the density of sources, confusion noise from z > 2 galaxies is expected to be small for NGST observations.