From compact jets to extended lobes: radio morphologies of distant quasars at z > 4
Abstract
High-redshift quasars play an essential role in studying the growth and evolution of supermassive black holes and active galactic nuclei (AGN). Radio-loud quasars additionally enable us to investigate the interactions between the jets and their environment. We aimed to reveal the radio morphology of three radio quasars at redshifts z>4 that contain milliarcsecond (mas) scale compact radio features according to previous very long baseline interferometry (VLBI) observations, but show significant flux density at arcsecond scales, indicating the presence of extended radio structure that cannot be sampled by the highest-resolution observations. We analysed radio interferometric data obtained at various angular resolutions and multiple frequencies, including observations made by the international Low-Frequency Array and the enhanced Multi-Element Remotely-Linked Interferometer Network. We also re-imaged archival European VLBI Network observations of our targets. Two quasars (J0813+3508 and J1231+3816) exhibit complex radio structures with hotspots, extended to tens of kpc. They resemble Fanaroff--Riley II-type radio galaxies with extremely bent jet morphology. The third object (J1548+3335) shows a one-sided structure of ≲ 10 kpc size. There was no sign of relativistic boosting at its previous mas-scale resolution radio observations. Its radio power and (inferred) linear size derived from the lower-resolution observations are similar to the known high-power compact steep-spectrum sources. We found that the previously detected mas-scale compact radio features are related to the centres of the AGN or in one case to one of the hotspots in an extended lobe.
Related
- GA-NIFS: sRMS, a new method for disentangling resolved and unresolved emission in integral field spectroscopy. Application to distant quasars
- Compact Core, Extended Reach: A Bipolar kpc-Scale Elongation in a Little Red Dot at z ≈ 5.5
- X-ray point sources towards the giant radio lobes of Centaurus A
- One Precessing Jet Pair, Diverse Core-Collapse Supernova Remnant Morphologies
- Simulating the jittering-jets explosion mechanism: circum-jet rings account for observed core-collapse supernova remnant morphologies
BibTeX
@misc{gabanyi2026from,
title = {{From compact jets to extended lobes: radio morphologies of distant quasars at z > 4}},
author = {K. É. Gabányi and M. Kunert-Bajraszewska and A. Krauze and S. Frey and M. Krezinger and Z. Paragi and H. Cao and T. An and L. I. Gurvits and K. Perger and T. Sbarrato and K. Rozgonyi},
howpublished = {arXiv},
year = {2026},
month = aug,
doi = {10.48550/arxiv.2607.25378},
eprint = {2607.25378},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.25378},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - From compact jets to extended lobes: radio morphologies of distant quasars at z > 4
AU - K. É. Gabányi
AU - M. Kunert-Bajraszewska
AU - A. Krauze
AU - S. Frey
AU - M. Krezinger
AU - Z. Paragi
AU - H. Cao
AU - T. An
AU - L. I. Gurvits
AU - K. Perger
AU - T. Sbarrato
AU - K. Rozgonyi
PY - 2026
DA - 2026/08/31
PB - arXiv
DO - 10.48550/arxiv.2607.25378
UR - https://arxiv.org/abs/2607.25378
AB - High-redshift quasars play an essential role in studying the growth and evolution of supermassive black holes and active galactic nuclei (AGN). Radio-loud quasars additionally enable us to investigate the interactions between the jets and their environment. We aimed to reveal the radio morphology of three radio quasars at redshifts z>4 that contain milliarcsecond (mas) scale compact radio features according to previous very long baseline interferometry (VLBI) observations, but show significant flux density at arcsecond scales, indicating the presence of extended radio structure that cannot be sampled by the highest-resolution observations. We analysed radio interferometric data obtained at various angular resolutions and multiple frequencies, including observations made by the international Low-Frequency Array and the enhanced Multi-Element Remotely-Linked Interferometer Network. We also re-imaged archival European VLBI Network observations of our targets. Two quasars (J0813+3508 and J1231+3816) exhibit complex radio structures with hotspots, extended to tens of kpc. They resemble Fanaroff--Riley II-type radio galaxies with extremely bent jet morphology. The third object (J1548+3335) shows a one-sided structure of ≲ 10 kpc size. There was no sign of relativistic boosting at its previous mas-scale resolution radio observations. Its radio power and (inferred) linear size derived from the lower-resolution observations are similar to the known high-power compact steep-spectrum sources. We found that the previously detected mas-scale compact radio features are related to the centres of the AGN or in one case to one of the hotspots in an extended lobe.
ER -