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" from a red V=22 mag elliptical galaxy. A mass distribution that 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 fourth image that is fainter than the detection limit. The inferred mass-to-light ratio is ~15 in solar units if the lens is at z=0.6. The lens models predict a velocity dispersion of ~280 km s^-1 that could be confirmed with spectroscopy.