The STRong lensing Insights into the Dark Energy Survey (STRIDES) 2016 follow-up campaign. II. New quasar lenses from double component fitting

TL;DR

This study reports the discovery and confirmation of two new gravitationally lensed quasars from the Dark Energy Survey, using double component fitting and follow-up observations, with implications for understanding lens environments.

Contribution

It introduces a new method combining double component fitting, morphological, and color analysis to identify and confirm gravitational lens candidates in the DES.

Findings

Confirmed two new gravitationally lensed quasars.

Identified 13 systems with multiple quasar images, including binaries and NIQs.

Lens modeling shows minimal environmental contribution needed for image configuration.

Abstract

We report upon the follow up of 34 candidate lensed quasars found in the Dark Energy Survey using NTT-EFOSC, Magellan-IMACS, KECK-ESI and SOAR-SAMI. These candidates were selected by a combination of double component fitting, morphological assessment and color analysis. Most systems followed up are indeed composed of at least one quasar image and 13 with two or more quasar images: two lenses, four projected binaries and seven Nearly Identical Quasar Pairs (NIQs). The two systems confirmed as genuine gravitationally lensed quasars are one quadruple at $z_s=1.713$ and one double at $z_s=1.515$. Lens modeling of these two systems reveals that both systems require very little contribution from the environment to reproduce the image configuration. Nevertheless, small flux anomalies can be observed in one of the images of the quad. Further observations of 9 inconclusive systems (including 7 NIQs) will allow to confirm (or not) their gravitational lens nature.