Binary and dual AGN are important observational tools for studying the dynamical evolution of galaxies and SMBHs. However, they are notoriously difficult to unambiguously detect. A new method for identifying possible multi-AGN makes use of the exquisite astrometric precision of Gaia to detect astrometrically-variable quasars, in tandem with the high radio spatial resolution of the VLA and the VLBA. Colloquially called varstrometry, this process is used to identify and characterize a new population of multi-AGN.
We present new radio observations with the VLA 2-4 GHz and 8-12 GHz bands of 18 quasars (0.7<z<2.9) exhibiting significant astrometric variability, as well as the VLBA 4cm and 13cm bands of a subset of seven quasars. All targets were selected from the SDSS DRQ16, cross-matched with the Gaia DR3. These observations have provided constraints on both the radio morphologies (down to submilliarcsecond scales) and the origin of the astrometric variability. In conjunction with significant multi-wavelength observations, we have investigated observed radio-optical offsets as well as identified several gravitationally-lensed quasars within the sample. The radio-optical offsets observed have been investigated in the context of the International Celestial Reference Frame. We provide constraints on applying the varstrometry method to high-resolution radio interferometry, and comment on the need for further study.