The SL2S Galaxy-scale Lens Sample. III. Lens Models, Surface Photometry and Stellar Masses for the final sample

TL;DR

This paper presents detailed lens models, surface photometry, and stellar mass estimates for a sample of 56 galaxy-scale lenses from the SL2S project, using HST and ground-based imaging to improve understanding of galaxy mass distribution and evolution.

Contribution

It provides new high-precision lens models and stellar mass measurements for a large lens sample, enhancing the study of galaxy evolution.

Findings

HST imaging yields higher success in confirming lenses.

Ground-based imaging provides competitive Einstein radius measurements.

Sample spans redshifts 0.3 to 0.8, ideal for studying galaxy evolution.

Abstract

We present Hubble Space Telescope (HST) imaging data and CFHT Near IR ground-based images for the final sample of 56 candidate galaxy-scale lenses uncovered in the CFHT Legacy Survey as part of the Strong Lensing in the Legacy Survey (SL2S) project. The new images are used to perform lens modeling, measure surface photometry, and estimate stellar masses of the deflector early-type galaxies. Lens modeling is performed on the HST images (or CFHT when HST is not available) by fitting the spatially extended light distribution of the lensed features assuming a singular isothermal ellipsoid mass profile and by reconstructing the intrinsic source light distribution on a pixelized grid. Based on the analysis of systematic uncertainties and comparison with inference based on different methods we estimate that our Einstein Radii are accurate to \sim3%. HST imaging provides a much higher success rate in confirming gravitational lenses and measuring their Einstein radii than CFHT imaging does. Lens modeling with ground-based images however, when successful, yields Einstein radius measurements that are competitive with spaced-based images. Information from the lens models is used together with spectroscopic information from the companion paper IV to classify the systems, resulting in a final sample of 39 confirmed (grade-A) lenses and 17 promising candidates. The redshifts of the main deflector span a range 0.3<zd< 0.8, providing an excellent sample for the study of the cosmic evolution of the mass distribution of early-type galaxies over the second half of the history of the Universe.