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Context. Previous studies based on the latest realisation of the International Celestial Reference Frame (ICRF3) have suggested a correlation between astrometric properties (such as the radio-optical offset) and redshift for active galactic nuclei (AGNs). Aims. We extend these investigations by using a large, all-sky sample of approximately 22 000 compact radio sources from the Radio Fundamental Catalogue (RFC) to examine this relationship in a systematic and statistically robust manner. Methods. We compiled redshifts for about 10 000 RFC sources over the range 0 1.3, where QSOs dominate. Similar behaviour is observed for several Gaia astrometric quantities, including astrometric uncertainties, proper motions, and G magnitudes. These behaviours can be largely explained by the dependence of Gaia astrometric performance on G magnitude and by the evolution of the G magnitude with redshift.
Zhang et al. (Fri,) studied this question.