Resolving the Powerful Radio-loud Quasar at z~6

TL;DR

This study uses high-resolution VLBA imaging to resolve the structure of the most radio-loud quasar known at z~6, revealing its morphology and estimating its age, thus providing insights into early supermassive black hole activity.

Contribution

First high-resolution VLBA imaging of a z~6 radio-loud quasar, resolving its structure and estimating its kinematic age.

Findings

Resolved the quasar into multiple components with 1.62 kpc extent.

Identified possible core-jet or CSO/MSO morphology.

Estimated the source's age to be around 10,000 years.

Abstract

We present high angular resolution imaging ($23.9 \times 11.3$ mas, $138.6 \times 65.5$ pc) of the radio-loud quasar PSO~J352.4034$-$15.3373 at $z=5.84$ 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 ($0\rlap{.}{''}28$) 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.