2001/10/17 by A. W. Blain, Andrew W. Blain · 1 citation
Physics and Astronomy · #Astronomy #Astrophysics #Galaxies: Formation, Evolution, Phenomena #Galaxy #Gravitational lens #Line-of-sight #Magnification #Millimeter #Optics #Physics #Radio Astronomy Observations and Technology #Redshift #Star formation #Submillimeter Array #Superconducting and THz Device Technology #Surface brightness #astro-ph
paper · pdf · doi:10.1046/j.1365-8711.2002.05058.x
published as Mon.Not.Roy.Astron.Soc. 330 (2002) 219 · 6 pages, 2 figures, MNRAS in press
arxiv created 2001/10/17 · openalex publication_date 2002/02/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The surface density of populations of galaxies with steep/shallow source counts is increased/decreased by gravitational lensing magnification. These effects are usually called ‘magnification bias’ and ‘depletion’, respectively. However, if sources are demagnified by lensing, then the situation is reversed, and the detectable surface density of galaxies with a shallow source count, as expected at the faintest flux densities, is increased. In general, demagnified sources are difficult to detect and study: exquisite subarcsec angular resolution and surface brightness sensitivity are required, and emission from the lensing object must not dominate the image. These unusual conditions are expected to be satisfied for observations made of the dense swarm of demagnified images that could form very close to the line of sight through the centre of a rich cluster of galaxies using the forthcoming submillimetre-wave Atacama Large Millimeter Array (ALMA) interferometer. The demagnified images of most of the background galaxies lying within about 1 arcmin of a rich cluster of galaxies could be detected in a single 18-arcsec-diameter ALMA field centred on the cluster core, providing an effective increase in the ALMA field of view. This technique could allow a representative sample of faint, 10–100 μJy submillimetre galaxies to be detected several times more rapidly than in a blank field.