MUSE adaptive-optics spectroscopy confirms dual active galactic nuclei and strongly lensed systems at sub-arcsec separation

¹ University of Trento, Via Sommarive 14, I-38123 Trento, Italy
² Università di Firenze, Dipartimento di Fisica e Astronomia, via G. Sansone 1, 50019 Sesto F.no, Firenze, Italy
³ INAF – Osservatorio Astrofisico di Arcetri, Via Largo E. Fermi 5, 50125 Firenze, Italy
⁴ Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa, Italy
⁵ Department of Physics, University of Arkansas, 226 Physics Building, 825 West Dickson Street, Fayetteville, AR 72701, USA
⁶ Institute of Theoretical Astrophysics, University of Oslo, P.O Box 1029 Blindern, 0315 Oslo, Norway
⁷ Department of Physics and Astronomy, University of California Los Angeles, 430 Portola Plaza, Los Angeles, CA 90095, USA
⁸ INAF – Padova Astronomical Observatory, Vicolo dell’ Osservatorio 5, 35122 Padova, Italy
⁹ INAF – Osservatorio Astronomico di Brera, via Brera 28, 20121 Milano, Italy
¹⁰ Physics and Astronomy Department “Augusto Righi”, Università di Bologna, Via Gobetti 93/2, 40129 Bologna, Italy
¹¹ Institut d’Astrophysique de Paris, 98bis Bd Arago, 75014 Paris, France

Received: 20 June 2023
Accepted: 4 July 2024

Abstract

The novel Gaia multi peak (GMP) technique has proven to be able to successfully select dual and lensed active galactic nuclei (AGN) candidates at sub-arcsecond separations. Both populations are important because dual AGN represent one of the central, still largely untested, predictions of ΛCDM cosmology, and compact lensed AGN allow us to probe the central regions of the lensing galaxies. In this work, we present high-spatial-resolution spectroscopy of 12 GMP-selected systems. We used the adaptive-optics assisted integral-field spectrograph MUSE at the VLT to resolve each system and investigate the nature of each component. All targets show the presence of two components confirming the GMP selection. We classify 4 targets as dual AGN, 3 as lensed quasar candidates, and 5 as a chance alignment of a star and an AGN. With separations ranging from 0.30″ to 0.86″, these dual and lensed systems are among the most compact systems discovered to date at z > 0.5. This is the largest sample of distant dual AGN with sub-arcsecond separations ever presented in a single paper.