1995/07/20 by B. Fort, Y. Mellier, Fort, B. +8
Physics and Astronomy · #Astrophysics (astro-ph) #Cosmology and Gravitation Theories #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #Pulsars and Gravitational Waves Research #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9507076
Tex. Tar compressed poscript files of the papers and figures are also available by anonymous ftp at ftp://summer.obs-mip.fr/pub/OUTGOING or upon request at [email protected]
arxiv created 1995/07/20 · openalex publication_date 1995/07/20 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We present a first attempt to reveal the possible existence of large foreground mass condensations directly responsible for the gravitational magnification of four distant luminous radiosources and one optical QSO. The technique uses a weak lensing analysis of the distant galaxies in the field of each source. We find a coherent shear map with a large magnification bias on the line of sight to Q1622+0328. The local shear in the field of the bright radiosources is also often correlated with nearby groups or poor clusters of galaxies. For three of them, the groups are identified as gravitational deflectors that magnify the radiosources. This suggests that a substantial amount of invisible mass is condensed in groups and poor clusters It may explain the origin of a large angular correlation between the distribution of distant radiosources and the distribution of low redshift galaxies. We discuss the feasability and consequences of a future systematic survey to investigate the problem of magnification bias in the fields of luminous distant objects and to probe the mass distributions of galaxy groups at intermediate redshifts.