Milliarcsecond-scale radio structure of the most distant BL Lac object candidate at redshift 6.57

Fuente: arXiv
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Hauptverfasser: Frey, S., Zhang, Y., Perger, K., An, T., Gabányi, K. É., Gurvits, L. I., Hwang, C. -Y., Koptelova, E., Paragi, Z., Fogasy, J.
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Veröffentlicht: 2023
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author Frey, S.
Zhang, Y.
Perger, K.
An, T.
Gabányi, K. É.
Gurvits, L. I.
Hwang, C. -Y.
Koptelova, E.
Paragi, Z.
Fogasy, J.
author_facet Frey, S.
Zhang, Y.
Perger, K.
An, T.
Gabányi, K. É.
Gurvits, L. I.
Hwang, C. -Y.
Koptelova, E.
Paragi, Z.
Fogasy, J.
contents The existence of accreting supermassive black holes up to billions of solar masses at early cosmological epochs (in the context of this work, redshifts z>=6) requires very fast growth rates which is challenging to explain. The presence of a relativistic jet can be a direct indication of activity and accretion status in active galactic nuclei (AGN), constraining the radiative properties of these extreme objects. However, known jetted AGN beyond z~6 are still very rare. The radio-emitting AGN J2331+1129 has recently been claimed as a candidate BL Lac object at redshift z=6.57, based on its synchrotron-dominated emission spectrum and the lack of ultraviolet/optical emission lines. It is a promising candidate for the highest-redshift blazar known to date. The aim of the observations described here was to support or refute the blazar classification of this peculiar source. We performed high-resolution radio interferometric imaging observations of J2331+1129 using the Very Long Baseline Array at 1.6 and 4.9 GHz in 2022 Feb. The images revealed a compact but slightly resolved, flat-spectrum core feature at both frequencies, indicating that the total radio emission is produced by a compact jet and originates from within a central 10-pc scale region. While these are consistent with the radio properties of a BL Lac object, the inferred brightness temperatures are at least an order of magnitude lower than expected from a Doppler-boosted radio jet, leaving the high-redshift BL Lac identification still an open question.
format Preprint
id arxiv_https___arxiv_org_abs_2312_15765
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Milliarcsecond-scale radio structure of the most distant BL Lac object candidate at redshift 6.57
Frey, S.
Zhang, Y.
Perger, K.
An, T.
Gabányi, K. É.
Gurvits, L. I.
Hwang, C. -Y.
Koptelova, E.
Paragi, Z.
Fogasy, J.
Astrophysics of Galaxies
High Energy Astrophysical Phenomena
The existence of accreting supermassive black holes up to billions of solar masses at early cosmological epochs (in the context of this work, redshifts z>=6) requires very fast growth rates which is challenging to explain. The presence of a relativistic jet can be a direct indication of activity and accretion status in active galactic nuclei (AGN), constraining the radiative properties of these extreme objects. However, known jetted AGN beyond z~6 are still very rare. The radio-emitting AGN J2331+1129 has recently been claimed as a candidate BL Lac object at redshift z=6.57, based on its synchrotron-dominated emission spectrum and the lack of ultraviolet/optical emission lines. It is a promising candidate for the highest-redshift blazar known to date. The aim of the observations described here was to support or refute the blazar classification of this peculiar source. We performed high-resolution radio interferometric imaging observations of J2331+1129 using the Very Long Baseline Array at 1.6 and 4.9 GHz in 2022 Feb. The images revealed a compact but slightly resolved, flat-spectrum core feature at both frequencies, indicating that the total radio emission is produced by a compact jet and originates from within a central 10-pc scale region. While these are consistent with the radio properties of a BL Lac object, the inferred brightness temperatures are at least an order of magnitude lower than expected from a Doppler-boosted radio jet, leaving the high-redshift BL Lac identification still an open question.
title Milliarcsecond-scale radio structure of the most distant BL Lac object candidate at redshift 6.57
topic Astrophysics of Galaxies
High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2312.15765