Version 1
: Received: 3 April 2024 / Approved: 4 April 2024 / Online: 4 April 2024 (10:08:42 CEST)
How to cite:
Sotnikova, Y.; Mikhailov, A.; Mufakharov, T.; An, T.; Kudryavtsev, D.; Mingaliev, M.; Udovitskiy, R.; Kudryashova, A.; Stolyarov, V.; Semenova, T. High–Redshift Quasars at z z≥3">≥ 3: Radio Variability and MPS/GPS Candidates. Preprints2024, 2024040363. https://doi.org/10.20944/preprints202404.0363.v1
Sotnikova, Y.; Mikhailov, A.; Mufakharov, T.; An, T.; Kudryavtsev, D.; Mingaliev, M.; Udovitskiy, R.; Kudryashova, A.; Stolyarov, V.; Semenova, T. High–Redshift Quasars at z ≥ 3: Radio Variability and MPS/GPS Candidates. Preprints 2024, 2024040363. https://doi.org/10.20944/preprints202404.0363.v1
Sotnikova, Y.; Mikhailov, A.; Mufakharov, T.; An, T.; Kudryavtsev, D.; Mingaliev, M.; Udovitskiy, R.; Kudryashova, A.; Stolyarov, V.; Semenova, T. High–Redshift Quasars at z z≥3">≥ 3: Radio Variability and MPS/GPS Candidates. Preprints2024, 2024040363. https://doi.org/10.20944/preprints202404.0363.v1
APA Style
Sotnikova, Y., Mikhailov, A., Mufakharov, T., An, T., Kudryavtsev, D., Mingaliev, M., Udovitskiy, R., Kudryashova, A., Stolyarov, V., & Semenova, T. (2024). High–Redshift Quasars at <em>z </em><span data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>z</mi><mo>≥</mo><mn>3</mn></math>">≥ 3: Radio Variability and MPS/GPS Candidates. Preprints. https://doi.org/10.20944/preprints202404.0363.v1
Chicago/Turabian Style
Sotnikova, Y., Vlad Stolyarov and Tamara Semenova. 2024 "High–Redshift Quasars at <em>z </em><span data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>z</mi><mo>≥</mo><mn>3</mn></math>">≥ 3: Radio Variability and MPS/GPS Candidates" Preprints. https://doi.org/10.20944/preprints202404.0363.v1
Abstract
We present a study of the radio variability of bright, $S_{1.4}\geq100$ mJy, high-redshift quasars at $z\geq3$ on timescales up to 30--40 years. The study involved simultaneous RATAN-600 measurements at frequencies of 2.3, 4.7, 8.2, 11.2, and 22.3 GHz in 2017--2020. In addition, data from the literature were used. We have found that the variability index $V_S$ of the quasars ranges from 0.02 to 0.96, with about half of the objects in the sample showing a variability index in the range of 0.25--0.50, which is comparable to that of the blazars at lower redshifts. The distribution of $V_S$ at 22.3 GHz is significantly different from that at 2.3--11.2 GHz, which may be attributed to the fact that a compact AGN core dominates at the source's rest frame frequencies greater than 45 GHz, leading to higher variability indices obtained at 22.3 GHz (the $V_S$ distribution peaks around 0.4) compared to the lower frequencies (the $V_S$ distribution peaks around 0.1--0.2). Several source groups with distinctive variability characteristics were found using cluster analysis of quasars. We propose 7 new candidates for gigahertz peaked-spectrum (GPS) sources and 5 new megahertz peaked-spectrum (MPS) sources based on their spectrum shape and variability features. Only 6 out of 23 sources previously reported as GPS demonstrate a low variability level typical of classical GPS sources ($V_{S} < 0.25$) at 4.7--22.3~GHz. When excluding the highly variable peaked-spectrum blazars, we expect no more than 20\% of the sources in the sample to be GPS candidates and no more than 10\% to be MPS candidates.
Keywords
galaxies; active; galaxies; high-redshift; quasars; general; radio continuum; galaxies
Subject
Physical Sciences, Astronomy and Astrophysics
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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