Discovery of Four kpc-Scale Binary AGNs

TL;DR

This paper reports the discovery of four binary active galactic nuclei (AGNs) separated by several kiloparsecs, identified through spectral features and confirmed by imaging and spectroscopy, highlighting an efficient detection method.

Contribution

The study presents the first confirmed kpc-scale binary AGNs identified via double-peaked emission lines, supported by deep imaging and spectroscopic evidence, demonstrating an effective detection approach.

Findings

Four kpc-scale binary AGNs discovered.

Deep imaging reveals tidal features and double stellar components.

Spectroscopy confirms dual Seyfert 2 nuclei with velocity offsets.

Abstract

We report the discovery of four kpc-scale binary AGNs. These objects were originally selected from the Sloan Digital Sky Survey based on double-peaked [O III] 4959,5007 emission lines in their fiber spectra. The double peaks could result from pairing active supermassive black holes (SMBHs) in a galaxy merger, or could be due to bulk motions of narrow-line region gas around a single SMBH. Deep near-infrared (NIR) images and optical slit spectra obtained from the Magellan 6.5 m and the APO 3.5 m telescopes strongly support the binary SMBH scenario for the four objects. In each system, the NIR images reveal tidal features and double stellar components with a projected separation of several kpc, while optical slit spectra show two Seyfert 2 nuclei spatially coincident with the stellar components, with line-of-sight velocity offsets of a few hundred km/s. These objects were drawn from a sample of only 43 objects, demonstrating the efficiency of this technique to find kpc-scale binary AGNs.