Resolving the Powerful Radio-loud Quasar at z~6

We present high angular resolution imaging ($23.9\times 11.3$ mas, $138.6 \times 65.5$pc)oftheradio-loudquasarPSOJ352.4034$-$15.3373at$z=5.84$ with the Very Long Baseline Array (VLBA) at 1.54 GHz. This quasar has the highest radio-to-optical flux density ratio at such a redshift, making it the radio-loudest source known to date at $z\sim 6$. The VLBA observations presented here resolve this quasar into multiple components with an overall linear extent of 1.62 kpc ($0\text{.}{}^{\mathrm{\prime }\mathrm{\prime }}28$) and with a total flux density of $6.57\pm 0.38$ mJy, which is about half of the emission measured at a much lower angular resolution. The morphology of the source is comparable with either a radio core with a one-sided jet, or a compact or a medium-size Symmetric Object (CSO/MSO). If the source is a CSO/MSO, and assuming an advance speed of $0.2c$, then the estimated kinematic age is $\sim {10}^4$ yr.