Thirty-fold: Extreme gravitational lensing of a quiescent galaxy at $z=1.6$

TL;DR

This paper reports the discovery of a highly gravitationally lensed quiescent galaxy at redshift 1.6, amplified by a factor of about 30, demonstrating the effectiveness of snapshot X-ray cluster surveys for studying faint distant galaxies.

Contribution

First identification and crude mass modeling of a strongly lensed quiescent galaxy at z=1.6, revealing extreme gravitational lensing effects.

Findings

Discovered a quiescent galaxy at z=1.6 with a lensing amplification of ~30.

Provided the first crude mass model of the lensing galaxy cluster.

Showed the potential of snapshot X-ray cluster surveys for lensing studies.

Abstract

We report the discovery of eMACSJ1341-QG-1, a quiescent galaxy at $z=1.594$ located behind the massive galaxy cluster eMACSJ1341.9$-$2442 ($z=0.835$). The system was identified as a gravitationally lensed triple image in Hubble Space Telescope images obtained as part of a snapshot survey of the most X-ray luminous galaxy clusters at $z>0.5$ and spectroscopically confirmed in ground-based follow-up observations with the ESO/X-Shooter spectrograph. From the constraints provided by the triple image, we derive a first, crude model of the mass distribution of the cluster lens, which predicts a gravitational amplification of a factor of $\sim$30 for the primary image and a factor of $\sim$6 for the remaining two images of the source, making eMACSJ1341-QG-1 by far the most strongly amplified quiescent galaxy discovered to date. Our discovery underlines the power of SNAPshot observations of massive, X-ray selected galaxy clusters for lensing-assisted studies of faint background populations.