The Discovery of a Five-Image Lensed Quasar at z = 3.34 using PanSTARRS1 and Gaia

TL;DR

This paper reports the discovery and detailed analysis of a gravitationally lensed quasar system at redshift 3.34, identified through Pan-STARRS and Gaia data, with follow-up spectroscopy and high-resolution imaging confirming its complex lensing structure.

Contribution

The study introduces a novel method combining Pan-STARRS, WISE, and Gaia data to discover high-redshift lensed quasars, and provides detailed mass modeling of the system.

Findings

Discovery of a four-image cusp lens with a fifth image.

Confirmation of quasar at redshift 3.34 through spectroscopy.

Mass modeling with two singular isothermal ellipsoids fits the lensing configuration.

Abstract

We report the discovery, spectroscopic confirmation, and mass modelling of the gravitationally lensed quasar system PS J0630-1201. The lens was discovered by matching a photometric quasar catalogue compiled from Pan-STARRS and WISE photometry to the Gaia DR1 catalogue, exploiting the high spatial resolution of the latter (FWHM $\sim $0.1") to identify the three brightest components of the lens. Follow-up spectroscopic observations with the WHT confirm the multiple objects are quasars at redshift $z_{q}=3.34$. Further follow-up with Keck AO high-resolution imaging reveals that the system is composed of two lensing galaxies and the quasar is lensed into a $\sim$2.8" separation four-image cusp configuration with a fifth image clearly visible, and a 1.0" arc due to the lensed quasar host galaxy. The system is well-modelled with two singular isothermal ellipsoids, reproducing the position of the fifth image. We discuss future prospects for measuring time delays between the images and constraining any offset between mass and light using the faintly detected Einstein arcs associated with the quasar host galaxy.