Persephone's Torch: A 15th Magnitude Quadruply-Lensed Quasar From the Couch Discovered with SPHEREx and the LBT

TL;DR

Persephone's Torch is the brightest quadruply-lensed quasar discovered, confirmed via SPHEREx data and adaptive optics, with unique flux anomalies and short time delays, promising for microlensing research.

Contribution

This paper reports the discovery and spectroscopic confirmation of the brightest known quadruply-lensed quasar using SPHEREx data and adaptive optics imaging.

Findings

Confirmed the quasar nature and redshift of Persephone's Torch.

Resolved four images with adaptive optics, revealing flux anomalies.

Predicted a total magnification of approximately 56.

Abstract

Here we report the spectroscopic and geometric confirmation of an extremely bright ($i=14.77$) and compact (Einstein radius of $\sim0.45''$) quadruply-lensed quasar at $z=2.22$, J1330$-$0905, which we dub Persephone's Torch. The system had been previously selected as a candidate lensed quasar based on large-area survey data; here we confirm its quasar nature and redshift using public spectrophotometry from the SPHEREx mission, a.k.a. "from the couch". Adaptive optics imaging with LBT/LUCI resolves four images in a "circular kite" configuration. The system is the brightest gravitationally-lensed quasar system ever found. While an elliptical power-law mass distribution plus external shear accurately reproduces the locations of the images and lensing galaxy, and predicts a total magnification of $\sim56$, the brightnesses of the lensed images present highly anomalous flux ratios. Together with short time delays between images ($\leq 2$ days), this makes Persephone's Torch a promising candidate for future microlensing studies. Our discovery highlights the potential of SPHEREx full-sky infrared spectrophotometry to uncover extraordinarily bright objects that have otherwise been overlooked.