DOI

https://doi.org/10.48717/m0b3-cc11

Project

EW040

Title

e-EVN: RSM06A, EW040A, EA071D, EA077B (BBHs)

Abstract

Sub-kpc dual-SMBHs are progenitors of eventually coalescing binary SMBHs. Recently a novel method named varstrometry has been introduced to search for high redshift dual-SMBHs, as the unsynchronized flux variability of dual AGNs will cause astrometric jitter detectable by Gaia without spatially resolving them. With previous e-MERLIN/EVN observations of 5 varstrometry selected radio dual-SMBHs candidates, we revealed clear Gaia-radio offsets in 3 candidates. This confirms the efficiency of varstrometry selection. We propose to observe 7 new candidates to further testify the efficiency of varstrometry selection of dual-SMBHs with weaker jitters thus more likely smaller projected separations (< 0.1 kpc), and to enlarge the valuable sample of sub-kpc dual-SMBHs candidates for statistical analyses. Such a larger sample may also enable the discovery of candidate double radio cores (if both quasars in a radio loud system are radio-loud), providing direct evidence of sub-kpc dual-SMBHs. The proposed observations are an essential step to provide candidates for future observations to completely distinguish alternatives (scenarios alternative to dual-SMBHs, or jet/core system instead of double cores). The total requested time is 32 hours.