Survey of Gravitationally-lensed Objects in HSC Imaging (SuGOHI). IV. Lensed quasar search in the HSC survey

TL;DR

This paper reports the discovery and analysis of 46 gravitationally lensed quasar candidates in the HSC survey, including spectroscopic confirmation and lens modeling, advancing methods for identifying and studying lensed quasars.

Contribution

It introduces a new lens search method in HSC data, confirms six candidates spectroscopically, and models their lensing properties, providing new insights into lensed quasars and galaxy evolution.

Findings

Identification of 46 lens candidates, including 3 known.

Spectroscopic redshifts obtained for 4 lens systems.

Evidence suggesting one source is a quasar and another a Lyman-alpha emitter.

Abstract

Strong gravitationally lensed quasars provide powerful means to study galaxy evolution and cosmology. We use Chitah to hunt for new lens systems in the Hyper Suprime$-$Cam Subaru Strategic Program (HSC SSP) S16A. We present 46 lens candidates, of which 3 are previously known. Including 2 additional lenses found by YattaLens, we obtain X-shooter spectra of 6 promising candidates for lens confirmation and redshift measurements. We report new spectroscopic redshift measurements for both the lens and source galaxies in 4 lens systems. We apply the lens modeling software Glee to model our 6 X-shooter lenses uniformly. Through our analysis of the HSC images, we find that HSCJ022622$-$042522, HSCJ115252$+$004733, and HSCJ141136$-$010216 have point-like lensed images, and that the lens light distribution is well aligned with mass distribution within 6 deg. Thanks to the X-shooter spectra, we estimate fluxes on the Baldwin- Phillips-Terlevich (BPT) diagram, and find that HSCJ022622$-$042522 has a probable quasar source, based on the upper limit of the Nii flux intensity. We also measure the FWHM of Ly$\alpha$ emission of HSCJ141136$-$010216 to be $\sim$254 km/s, showing that it is a probable Lyman-$\alpha$ emitter.