Discovery of a Quadruple Lens in CANDELS with a Record Lens Redshift z=1.53

TL;DR

This paper reports the discovery of the first strong galaxy lens at redshift greater than 1, revealing a highly magnified, low-mass starburst galaxy at high redshift with significant implications for understanding early universe star formation.

Contribution

It presents the first confirmed strong galaxy lens at z>1, combining spectroscopy and imaging to analyze a highly magnified, low-mass starburst galaxy at high redshift.

Findings

First strong galaxy lens at z>1 discovered.

Source galaxy is highly magnified with intense starburst activity.

Dark matter fraction within the Einstein radius is constrained to less than 60%.

Abstract

Using spectroscopy from the Large Binocular Telescope and imaging from the Hubble Space Telescope we discovered the first strong galaxy lens at z(lens)>1. The lens has a secure photometric redshift of z=1.53+/-0.09 and the source is spectroscopically confirmed at z=3.417. The Einstein radius (0.35"; 3.0 kpc) encloses 7.6 x 10^10 Msol, with an upper limit on the dark matter fraction of 60%. The highly magnified (40x) source galaxy has a very small stellar mass (~10^8 Msol) and shows an extremely strong [OIII]_5007A emission line (EW_0 ~ 1000A) bolstering the evidence that intense starbursts among very low-mass galaxies are common at high redshift.