Observation and Confirmation of Nine Strong Lensing Systems in Dark Energy Survey Year 1 Data

TL;DR

This paper reports the discovery and confirmation of nine new strong gravitational lensing systems from Dark Energy Survey Year 1 data, using candidate selection, spectroscopic follow-up, and analysis of lens properties.

Contribution

It presents the first confirmation of nine strong lensing systems in DES Year 1 data, demonstrating an effective candidate selection and spectroscopic confirmation methodology.

Findings

Confirmed nine new strong lensing systems

Spectroscopic analysis provided redshifts and mass estimates

Lens systems have separations of 2-9 arcsec and masses of 10^12-10^13 solar masses

Abstract

We describe the observation and confirmation of \nbconfirmtext\ new strong gravitational lenses discovered in Year 1 data from the Dark Energy Survey (DES). We created candidate lists based on a) galaxy group and cluster samples and b) photometrically selected galaxy samples. We selected 46 candidates through visual inspection and then used the Gemini Multi-Object Spectrograph (GMOS) at the Gemini South telescope to acquire spectroscopic follow-up of 21 of these candidates. Through analysis of this spectroscopic follow-up data, we confirmed nine new lensing systems and rejected 2 candidates, but the analysis was inconclusive on 10 candidates. For each of the confirmed systems, we report measured spectroscopic properties, estimated \einsteinradiussub, and estimated enclosed masses. The sources that we targeted have an i-band surface brightness range of iSB ~ 22 - 24 mag arcsec^2 and a spectroscopic redshift range of zspec ~0.8 - 2.6. The lens galaxies have a photometric redshift range of zlens ~ 0.3 - 0.7. The lensing systems range in image-lens separation 2 - 9 arcsec and in enclosed mass 10^12 - 10^13 Msol.