SDSS J131339.98+515128.3: A new gravitationally lensed quasar selected based on near-infrared excess

TL;DR

This paper reports the discovery of a new gravitationally lensed quasar identified through near-infrared excess, demonstrating an effective method for finding such systems in large surveys.

Contribution

The study introduces a novel near-infrared excess selection technique for identifying gravitationally lensed quasars in large astronomical datasets.

Findings

Discovered a new gravitationally lensed quasar at redshift 1.875

Confirmed the lensing galaxy at redshift 0.194

Validated near-IR excess as an efficient selection method

Abstract

We report the discovery of a new gravitationally lensed quasar, SDSS J131339.98+515128.3, at a redshift of 1.875 with an image separation of 1.24". The lensing galaxy is clearly detected in visible-light follow-up observations. We also identify three absorption-line doublets in the spectra of the lensed quasar images, from which we measure the lens redshift to be 0.194. Like several other known lenses, the lensed quasar images have different continuum slopes. This difference is probably the result of reddening and microlensing in the lensing galaxy. The lensed quasar was selected by correlating Sloan Digital Sky Survey (SDSS) spectroscopic quasars with Two Micron All Sky Survey (2MASS) sources and choosing quasars that show near-infrared (IR) excess. The near-IR excess can originate, for example, from the contribution of the lensing galaxy at near-IR wavelengths. We show that the near-IR excess technique is indeed an efficient method to identify lensed systems from a large sample of quasars.