SDSS Giant Arcs Survey ("SGAS")

Strong gravitational lensing models for 37 galaxy clusters from the Sloan Digital Sky Survey Giant Arcs Survey (SGAS) are made available as an HLSP, observed by HST GO13003 Cycle 20 large program (PI: Gladders). The lens models are constructed based on multi-band HST WFC3 imaging. The team supplemented these imaging data with ground-based imaging and spectroscopy from Magellan, Gemini, Apache Point Observatory, and the Multiple Mirror Telescope, in order to detect and spectroscopically confirm new multiply imaged lensed background sources behind the clusters. In the paper that accompanies this data release, Sharon et al. (2020), the team report the list of lensing constraints, and spectroscopic or photometric redshifts of sources in these fields, including cluster galaxies and background sources. The strong lensing mass models are constructed based on all available lensing evidence.

The HLSP include lens model outputs (kappa, gamma) for the best-optimized model and a range of maps drawn from sets in the MCMC that sample the parameter space, from which one can derive lens model properties such as cluster masses, magnification, deflection, and their uncertainties. The models were produced using the parametric lens modeling LENSTOOL (Jullo et al. 2007). The team refers the user to Sharon et al. (2020) for detailed information on the construction of the lens models, assessment of the quality of each model, and caveats. The team cautions the user that the derived lens models span a wide range of quality, which depends on the availability of constraints and the limitations due to lensing geometry. Users should consult the paper before making use of any model product.