High-resolution imaging of two radio quasars at the end of the reionization epoch

Journal article (2023)

Authors

Krisztina Perger Konkoly Observatory Hungarian Academy of Sciences
Yingkang Zhang Chinese Academy of Sciences
Sándor Frey Eötvös University, Konkoly Observatory Hungarian Academy of Sciences
Tao An Chinese Academy of Sciences
Krisztina Éva Gabányi Eötvös University, Konkoly Observatory Hungarian Academy of Sciences
L. Gurvits Astrodynamics & Space Missions - Aerospace Engineering , Joint Institute for VLBI ERIC
Chorng Yuan Hwang National Central University Taiwan
Ekaterina Koptelova National Central University Taiwan
Zsolt Paragi Joint Institute for VLBI ERIC
Ailing Wang Chinese Academy of Sciences
Research Group
Astrodynamics & Space Missions (Aerospace Engineering) (TU Delft)
Copyright: © 2023 Krisztina Perger, Yingkang Zhang, Sándor Frey, Tao An, Krisztina E. Gabányi, L. Gurvits, Chorng Yuan Hwang, Ekaterina Koptelova, Zsolt Paragi, Ailing Wang
DOI
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https://doi.org/10.22323/1.428.0024
More Info
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Published Date

2023

Language

English

Faculty

Aerospace Engineering

Department

Space Engineering

Research Group

Astrodynamics & Space Missions

Abstract

There are approximately 250 quasars discovered at redshift z ≥ 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.