A possible gravitational lens in the Hubble Deep Field South

Abstract

We model an apparent gravitational lens system HDFS 2232509-603243 in the Hubble Deep Field South. The system consists of a blue V=25 mag arc separated by 0.9 arcsec from a red V=22 mag elliptical galaxy. A mass distribution which follows the observed light distribution with a constant mass-to-light ratio can fit the arc component positions if external shear is added. A good fit is also obtained with simple parameterized models, and all the models predict a forth image fainter than the detection limit. The inferred mass-to-light ratio is roughly 15 in solar units if the lens is at redshift 0.6. The lens models predict a velocity dispersion of about 280 km/s which could be confirmed with spectroscopy.