3 years ago

Serendipitous discovery of quadruply-imaged quasars: two diamonds.

John R. Lucey, Timo Anguita, Paul L. Schechter, Russell J. Smith

Gravitationally lensed quasars are powerful and versatile astrophysical tools, but they are challengingly rare. In particular, only ~15 well-characterized quadruple systems are known to date. To refine the target catalogue for the forthcoming Taipan Galaxy Survey, the images of a large number of sources are being visually inspected in order to identify objects that are confused by a foreground star or galaxies that have a distinct multi-component structure.

An unexpected by-product of this work has been the serendipitous discovery of about a dozen galaxies that appear to be lensing quasars, i.e. pairs or quartets of foreground stellar objects in close proximity to the target source. Here we report two diamond-shaped systems. Follow-up spectroscopy with the IMACS instrument on the 6.5m Magellan Baade telescope confirms one of these as a z = 1.975 quasar quadruply lensed by a double galaxy at z = 0.293. Photometry from publicly available survey images supports the conclusion that the other system is a highly sheared quadruply-imaged quasar.

In starting with objects thought to be galaxies, our lens finding technique complements the conventional approach of first identifying sources with quasar-like colours and subsequently finding evidence of lensing.

Publisher URL: http://arxiv.org/abs/1711.02674

DOI: arXiv:1711.02674v1

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