DOI

https://doi.org/10.48717/z2ze-bv69

Project

ES103

Title

Confirmation of close dual quasars at z=0.6-2.5

Abstract

Galaxies generally harbour super-massive black holes (SMBHs) in their nuclei, which form and evolve together with the galaxies. Central SMBHs are expected to interact following the merger of two galaxies, and can eventually coalesce to form a single, more massive SMBH and emit gravitational wave signals. Characterisation of SMBH pairs at different evolutionary stages are thus important for galaxy evolution and multi-messenger astrophysics. However, there is a dearth of direct observational constraints on the SMBH merger rate and its redshift evolution as the observed population of SMBH pairs to date is still small and limited to low redshifts (z < 0.5). This proposal aims to provide additional new constraints on the incidence of dual SMBHs, especially at higher redshifts, by uncovering a population of quasar pairs at both early and advanced stages of merging using a novel astrometric selection technique. We have identified five radio-bright candidate dual quasars with expected separations of 0.5-3 kpc at 0.6 < z < 2.5 using this new technique. The proposed VLBI observations will confirm the binary nature of these targets, and pave the way for discovering a larger population of high-redshift dual SMBHs in the near future.