2-6 September 2024
CJD Bonn Castell
Europe/Berlin timezone
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Contribution

Faint compact radio quasars at redshifts z>5 observed with the European VLBI Network

Speakers

  • Mr. Máté KREZINGER

Primary authors

Co-authors

Content

High-redshift quasars provide unique information about the formation and evolution of the first galaxies and supermassive black holes (SMBHs) in the early ~1 billion years old Universe. Powerful relativistic jets, hosted by radio quasars, are thought to have an important role in building up SMBHs for such a short period of time. Thanks to dedicated high-resolution VLBI observations, our knowledge of the high-redshift (z > 5) radio quasars has greatly expanded. Despite the efforts, due to the limited amount of targets, the sample of VLBI-observed radio quasars is still too scarce to allow meaningful statistical conclusions. With our project, we aim to extend the list of VLBI-observed radio quasars while also investigate how the source structure and physical parameters are related to the radio loudness. We have selected a sample of 10 faint radio quasars at 5 < z < 6 with radio-loudness indices ranging from 0.9 to 76 for observations with the EVN at 1.7 GHz. In addition to the EVN observations, we collected single-dish and low-resolution radio interferometric data to study the spectral properties and variability of our sources. A high, 90% detection rate was achieved. Both radio-quiet and radio-loud sources were detected with single compact radio components. By extending our sample with other VLBI-detected z > 5 sources from the literature, we investigated relations between physical parameters such as radio loudness, brightness temperature and monochromatic radio power.