Friday, 8 August, 1997 at 3pm

Andrew Blain - MRAO

"Gravitational lensing in the submillimetre waveband"

ABSTRACT: "The counts of dusty extragalactic sources are expected to rise steeply at faint flux densities in the submillimetre waveband. This leads to a remarkable excess of sources at redshifts greater than unity in faint submillimetre-selected samples, which should soon be detected using SCUBA. The probability that a galaxy is gravitationally lensed by galaxies along the line-of-sight increases with redshift, and when combined with a count that is biased to large redshifts, the submillimetre waveband is the ideal place in which to detect lensed galaxies. Perhaps 10% of a carefully-selected sample could be lensed by a factor of at least 2. The basis of this assertion, the prospects for observational verification of the predictions, and their potential utility for investigating cosmological parameters are discussed. Lensing by clusters of galaxies, and its implications for observations of the Sunyaev--Zel'dovich effect are also mentioned."