High-resolution Imaging of Two Radio Quasars at the End of the Reionization Epoch

Abstract

There are approximately 250 quasars discovered at redshift $z\ge 6$, of which only a handful were detected in radio bands, and even fewer were imaged with the highest resolution very long baseline interferometry (VLBI) technique. Here we report the results of our dual-frequency observations with the Very Long Baseline Array (VLBA) of two such recently discovered quasars, VIKING J231818.35$-$311346.3 at $z=6.44$ and FIRST J233153.20$+$112952.11 at $z=6.57$. Both extremely distant sources were imaged with VLBI for the first time. The radio properties of the former are consistent with those of quasars with young radio jets. The latter has an UV/optical spectrum characteristic of BL Lac objects, of which no others have been found beyond redshift 4 so far. Our VLBA observations revealed a flat-spectrum compact radio source.

5 pages, 2 figures; to appear in the proceedings of the 15th European VLBI Network Symposium and Users' Meeting (EVN2022), 11-15 July 2022, University College Cork, Ireland

References in corpus (7)

• Parsec-scale properties of the radio brightest jetted AGN at z > 6
• High-resolution double morphology of the most distant known radio quasar at z=6.12
• Radio Detection of VIK J2318$-$3113, the Most Distant Radio-Loud Quasar ($z$=6.44)
• Resolving the Radio Emission from the Quasar P172+18 at $z=6.82$
• VLBI observations of VIK J2318-3113, a quasar at z = 6.44
• Milli-arcsecond imaging of the radio emission from the quasar with the most massive black hole at reionization
• Constraining the Radio Properties of the $z$=6.44 QSO VIK J2318$-$3113