VLBI observation of the newly discovered z=5.18 quasar SDSS J0131-0321

TL;DR

This paper reports VLBI observations of the high-redshift, radio-loud quasar SDSS J0131-0321 at z=5.18, revealing a compact radio core with high brightness temperature and flux variability, suggesting blazar characteristics.

Contribution

First VLBI imaging of the z=5.18 quasar SDSS J0131-0321, demonstrating its compactness, high brightness temperature, and blazar nature at such high redshift.

Findings

Detected a single compact radio component with T_B~10^{11} K.

Observed significant flux density variation over time.

Indications of blazar activity at high redshift.

Abstract

Few high-redshift, radio-loud quasars are known to date. The extremely luminous, radio-bright quasar, SDSS J013127.34-032100.1 was recently discovered at a redshift of $z=5.18$. We observed the source with high resolution very long baseline interferometry (VLBI) at 1.7 GHz with the European VLBI Network (EVN) and found a single compact radio component. We estimated a lower limit to the brightness temperature of the detected radio component, T_B~10^{11} K. Additionaly, when compared to archival radio data, the source showed significant flux density variation. These two findings are indicative of the blazar nature of the source.