DOI

https://doi.org/10.48717/gj4z-jh75

Project

ES093

Title

The parsec-scale view of the most distant blazar at z = 6.1

Abstract

We propose EVN + e-MERLIN sensitive observations at L-, C- and K- bands (the latter - including KVN) of PSO J0309+27, the first and so far the only blazar at z > 6, discovered recently by our group. This source is the strongest radio-loud AGN currently known at z > 6. To characterize its radio SED and explore its VLBI-scales we conducted VLBA DDT observations in April 2020, which revealed a bright core-jet morphology from L- to X- bands extended to 500 parsecs in projection. Here, we request multi-band observations with the EVN + e MERLIN + KVN to investigate both intermediate and small scales of this blazar with high image fidelity by exploiting the high sensitivity on the short spacings due to the inclusion of the e-MERLIN and KVN antennas. The L- and C-band observations will allow us also to investigate flux density variability in this source. The proposed EVN + e-MERLIN observations will complement our rich multi-band campaign, and provide the crucial information for broadband characterisation of this unique high-z source. We note that technical feasibility of our project has been confirmed by trial QUASAR runs at L- and C-bands in March 2020.