DULAG: A DUal and Lensed AGN candidate catalog with the Gaia multipeak method

¹ Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, China
² University of Chinese Academy of Sciences, Beijing 100049, China
³ University of Trento, Via Sommarive 14, 38123 Trento, Italy
⁴ Università di Firenze, Dipartimento di Fisica e Astronomia, via G. Sansone 1, 50019 Sesto F.no, Firenze, Italy
⁵ INAF – Osservatorio Astrofisico di Arcetri, largo E. Fermi 5, 50125 Firenze, Italy

^★ Corresponding authors; shilongliao@shao.ac.cn, filippo.mannucci@inaf.it, zxqi@shao.ac.cn

Received: 18 September 2024
Accepted: 6 November 2024

Abstract

Context. A series of studies have demonstrated that the Gaia multipeak (GMP) method is a very efficient technique for selecting active galactic nucleus (AGN) pair candidates. The number of candidates is determined by the size of the input AGN catalog, and is usually limited to spectroscopically confirmed objects.

Aims. The objective of this work is to compile a larger and highly reliable catalog of GMP AGN pair candidates extracted from the six million objects of the Gaia AGN catalog, the majority of which lack spectroscopic information.

Methods. In order to ascertain the differences between GMP AGN pair candidates and normal AGNs in terms of their properties, we conducted an investigation using samples of GMP AGNs. These differences were employed to establish optimal selection criteria, which ultimately led to the identification of a highly reliable candidate catalog.

Results. We find significant differences between normal AGNs and GMP AGN pair candidates in terms of their astrometry and multi-band color distribution. We compiled the DUal and Lensed AGN candidate catalog with the GMP method (DULAG), which comprises 5286 sources, and is accompanied by a highly reliable Golden sample of 1867 sources. A total of 37 sources in the Golden sample have been identified as dual AGN or lensed AGN. For the majority of sources in the Golden sample, we provide reference redshifts and find three close AGN pair candidates among them.