Observation and Confirmation of Six Strong Lensing Systems in The Dark Energy Survey Science Verification Data

TL;DR

This paper reports the discovery and confirmation of six strong gravitational lensing systems in DES data, including three new systems, providing valuable insights into mass distribution in galaxy groups and clusters.

Contribution

First identification and spectroscopic confirmation of six strong lensing systems in DES SV data, including three new discoveries, with detailed mass and Einstein radius estimates.

Findings

Confirmed six strong lensing systems, three newly discovered.

Estimated Einstein radii range from 5.0 to 8.6 arcseconds.

Enclosed masses range from 7.5 x 10^{12} to 6.4 x 10^{13} solar masses.

Abstract

We report the observation and confirmation of the first group- and cluster-scale strong gravitational lensing systems found in Dark Energy Survey (DES) data. Through visual inspection of data from the Science Verification (SV) season, we identified 53 candidate systems. We then obtained spectroscopic follow-up of 21 candidates using the Gemini Multi-Object Spectrograph (GMOS) at the Gemini South telescope and the Inamori-Magellan Areal Camera and Spectrograph (IMACS) at the Magellan/Baade telescope. With this follow-up, we confirmed six candidates as gravitational lenses: Three of the systems are newly discovered, and the remaining three were previously known. Of the 21 observed candidates, the remaining 15 were either not detected in spectroscopic observations, were observed and did not exhibit continuum emission (or spectral features), or were ruled out as lensing systems. The confirmed sample consists of one group-scale and five galaxy cluster-scale lenses. The lensed sources range in redshift z ~ 0.80-3.2, and in i-band surface brightness i_{SB} ~ 23-25 mag/sq.-arcsec. (2" aperture). For each of the six systems, we estimate the Einstein radius and the enclosed mass, which have ranges ~ 5.0 - 8.6" and ~ 7.5 x 10^{12} - 6.4 x 10^{13} solar masses, respectively.