The Sloan Lens ACS Survey. V. The Full ACS Strong‐Lens Sample

TLDR

The foreground galaxies are primarily early‑type, spanning redshifts 0.05–0.5 and velocity dispersions 160–400 km s⁻¹, while the background emission‑line galaxies lie at 0.2–1.2. The study presents definitive data for 131 strong gravitational lens candidates observed with HST/ACS by the SLACS Survey. Targets were selected via higher‑redshift emission lines and lower‑redshift continuum in a single SDSS spectrum; for 63 clear lenses, singular isothermal ellipsoid and light‑traces‑mass models were fitted to ACS imaging, with mass measurements complemented by ACS photometry and SDSS spectroscopy. The survey confirms 70 clear lensing systems and 19 probable ones, offering a unique resource that demonstrates the SLACS sample is statistically consistent with a random draw from SDSS massive early‑type galaxies.

Abstract

We present the definitive data for the full sample of 131 strong gravitational lens candidates observed with the Advanced Camera for Surveys (ACS) aboard the Hubble Space Telescope by the Sloan Lens ACS (SLACS) Survey. All targets were selected for higher-redshift emission lines and lower-redshift continuum in a single Sloan Digital Sky Survey (SDSS) spectrum. The foreground galaxies are primarily of early-type morphology, with redshifts from approximately 0.05 to 0.5 and velocity dispersions from 160 km/s to 400 km/s; the faint background emission-line galaxies have redshifts ranging from about 0.2 to 1.2. We confirm 70 systems showing clear evidence of multiple imaging of the background galaxy by the foreground galaxy, as well as an additional 19 systems with probable multiple imaging. For 63 clear lensing systems, we present singular isothermal ellipsoid and light-traces-mass gravitational lens models fitted to the ACS imaging data. These strong-lensing mass measurements are supplemented by magnitudes and effective radii measured from ACS surface-brightness photometry and redshifts and velocity dispersions measured from SDSS spectroscopy. These data constitute a unique resource for the quantitative study of the inter-relations between mass, light, and kinematics in massive early-type galaxies. We show that the SLACS lens sample is statistically consistent with being drawn at random from a parent sample of SDSS galaxies with comparable spectroscopic parameters and effective radii, suggesting that the results of SLACS analyses can be generalized to the massive early-type population.