Gravitational lenses and lens candidates identified from the COSMOS field

TL;DR

This study conducted a manual search of the COSMOS field, identifying new gravitational lenses and candidates among nearly 285,423 galaxies, highlighting the potential and limitations of visual detection methods.

Contribution

It provides a comprehensive manual search for gravitational lenses in the COSMOS field, discovering new lenses and assessing the effectiveness of visual identification techniques.

Findings

Identified 2 certain and 1 probable new gravitational lenses.

Presented a list of 112 candidate lens systems.

Estimated that about 10^6 objects can be examined visually with reasonable effort.

Abstract

A complete manual search has been carried out of the list of 285423 objects, nearly all of them galaxies, identified in the 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. (2008). 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 10^6 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.