Two radio cores in GPS J1543-0757: a new dual supermassive black hole system?

TL;DR

This paper reports the discovery of a dual supermassive black hole system in the radio galaxy J1543-0757, identified through multifrequency VLBI observations revealing two active nuclei separated by 46 milliarcseconds.

Contribution

It presents the first evidence of a dual SMBH system in J1543-0757 using high-resolution radio imaging, providing insights into close black hole pairs and gravitational wave sources.

Findings

Two compact, variable, flat-spectrum nuclei identified

Nuclei are stationary, jets show outward motion

Implications for gravitational wave source populations

Abstract

We report on the discovery of a dual supermassive black hole system in the radio galaxy J1543-0757, with a projected separation between the two black holes of 46 mas. The result is based on recent multifrequency observations using the Very Long Baseline Array and European VLBI Network, which reveal two compact, variable, flat-spectrum, active nuclei within the elliptical host galaxy of J1543-0757. Multiepoch observations from the VLBA also provide constraints on the spectral index and proper motions of all components. The flat spectra of both N and S at both frequencies strongly support that these radio components are associated with two separate, accreting supermassive black holes (SMBHs). The two nuclei appear stationary, while the jets emanating from the weaker of the two nuclei appear to move out and terminate in bright hot spots. The discovery of this system has implications for the number of close dual black holes that might be sources of gravitational radiation.