Gravitational lenses and lens candidates identified from the COSMOS field

Abstract

A complete manual search has been carried out of the list of 285423 objects, nearly all of them galaxies, identified in the Cosmic Evolution Survey (COSMOS) field that are brighter than I = 25. Two certain and one highly probable new gravitational lenses are found, in addition to the lenses and candidate lens systems previously found by Faure et al. A further list of 112 candidate lens systems is presented. Few of these are likely to be true gravitational lens systems, most being star-forming rings or pairs of companion galaxies. It is possible to examine of order 10⁶ objects by eye in a reasonable time, although reliable detection of lenses by such methods is likely to be possible only with high-resolution data. The loss of completeness involved in a rapid search is estimated as up to a factor of 2, depending on the morphology of the lens candidate.