Search for quasar pairs with Gaia astrometric data III. Confirmation of 16 dual quasars and 36 projected quasars

TL;DR

This study confirms 16 dual quasar systems and 36 projected quasar pairs using Gaia astrometric data and DESI spectroscopy, providing insights into galaxy mergers and gravitational lensing.

Contribution

It presents the third installment in a series, introducing new spectroscopic confirmations of quasar pairs and candidates, including a potential gravitational lens system.

Findings

Confirmed 16 dual quasars with redshifts 0.609-2.758.

Identified 36 projected quasars with redshifts 0.377-3.399.

Discovered a potential gravitational lens system.

Abstract

Dual quasars separated at kiloparsec scale are widely regarded as precursors to binary supermassive black holes and offer a key insight into the dynamical evolution of galaxy mergers. Our series of studies focus on searching for dual quasars by using a selection strategy of zero proper motion and zero parallax to isolate quasar candidates near known ones and by follow-up spectroscopy of the candidates. This paper, the third in the series, reports the spectroscopic confirmations of our quasar pair candidates primarily based on the data of the DESI DR1. We newly identified 16 dual quasars and 36 projected quasars. The redshifts of the 16 dual quasars range from 0.609 to 2.758, with a median of 1.46. One notable system, J0023+0417, exhibits nearly identical spectral features in the two members and shows evidence of a potential foreground galaxy, making it a high-confidence strong gravitational lensing system. The redshift of the 36 projected quasars are from 0.377 to 3.399, with a median of 1.663. Among them, four have projected distances below 30 kpc, offering valuable opportunities to probe the circumgalactic medium (CGM) of the foreground host galaxy through absorption lines.