Radio Jet Proper-motion Analysis of Nine Distant Quasars above Redshift 3.5

Up to now, jet kinematic studies of radio quasars have barely reached beyond the redshift range at $z>3.5$. This significantly limits our knowledge high-redshift jets, which can provide key information for understanding nature and growth black holes in early Universe. In this paper, we selected 9 radio-loud $z>3.5$ display milliarcsec-scale morphology. We provided evidence on source by presenting high-resolution very long baseline interferometry (VLBI) images sample 8.4~GHz frequency making spectral index maps. also consider Gaia optical positions that are available 7 out quasars, a better identification components within structures. find 6 sources be classified as core--jet blazars. The remaining 3 objects more likely young, jetted sources, compact symmetric objects. By including multi-epoch archival VLBI data, obtained component proper motions estimated geometric parameters (Doppler factor, Lorentz viewing angle). Our results show $z>3.5$, apparent transverse speeds do not exceed 20 times speed light ($c$). is consistent with earlier quasar measurements literature tendency derived from low-redshift blazars fast ($>40\,c$) only occur low redshifts. paper contribute cosmological evolution AGN.