Multiwavelength variability of the blazar AO 0235+164

ABSTRACT We present a study of the multiwavelength (MW) variability of the blazar AO 0235$+$164 based on the radio-to-$\gamma$-ray data covering a long time period from 1997 to 2023. The radio data are represented by the 1–22 GHz measurements from the SAO RAS RATAN-600 radio telescope, the 5 and 8 GHz data from the IAA RAS RT-32 telescopes, and the 37 GHz data from the RT-22 telescope of CrAO RAS. The optical measurements in the R-band were collected with the SAO RAS 1-m Zeiss-1000 and 0.5-m AS-500/2 telescopes. Additionally, we used the archive data at 230 GHz from the Submillimetre Array and the $\gamma$-ray data in the 0.1–100 GeV band from the Fermi-LAT point source 4FGL-DR2 catalogue. The variability properties during four epochs containing major flares and one epoch of relatively low activity were analysed using the fractional variability indices, discrete correlation functions, Lomb–Scargle periodograms, and structure functions. A significant correlation ($\ge \!2\sigma$) between the radio, optical, and $\gamma$-ray bands is found for all these periods with time delays from 0 to 1.7 yr. The relation between time delay and frequency is described by a linear law with a negative slope of $-10$ d GHz$^{-1}$. The discovered properties of MW variability for the low-activity period and for flaring states suggest that the mechanisms dominating the radio–$\gamma$-ray variations are not substantially different. The detected quasi-periodic oscillations of about 6 and 2 yr are tentative, as the time span of the observations includes fewer than four full cycles for the radio and optical data and only about three cycles for the Fermi-LAT data. These results should be interpreted with caution, given the limited number of observed cycles and the influence of red noise. We used cluster analysis to reliably separate the high and low-activity states and determined statistical differences in the main properties of AO 0235$+$164 non-thermal emission. The physical parameters of the radio jet were obtained using the Hedgehog model applied to the average radio spectrum of AO 0235$+$164 in the range 0.1–300 GHz. The effectiveness of replacing electrons with protons in the synchrotron radio emission of relativistic jets is shown for describing the nature of blazars and the generation of high-energy neutrinos.

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Journal
Monthly Notices of the Royal Astronomical Society
Published
2024-11-06
DOI
https://doi.org/10.1093/mnras/stae2491
Citations
6
Primary Topic
Astrophysics and Cosmic Phenomena
Type
article
Field-Weighted Citation Impact
3.96

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article

Multiwavelength variability of the blazar AO 0235+164

Vasily Vasilievich Vlasyuk, A. E. Volvach, A. V. Popkov, Abhik Ghosh et al.
6 citations
Monthly Notices of the Royal Astronomical Society
Astrophysics and Cosmic Phenomena
3.96
article

Multiwavelength variability of the blazar AO 0235+164

Vasily Vasilievich Vlasyuk, A. E. Volvach, A. V. Popkov, Abhik Ghosh, M. A. Kharinov, D. O. Kudryavtsev, М. Г. Мингалиев, А. С. Москвитин, Y. Y. Kovalev, А. К. Эркенов, Yu. V. Sotnikova, Y A Kovalev, Т. В. Муфахаров, Т. А. Семенова, L. N. Volvach, E. V. Emelianov, П. Г. Цыбулев, O. I. Spiridonova, Mark Gurwell, I. A. Rakhimov, S. Razzaque, М. Л. Хабибуллина, А. Г. Михайлов, Т. А. Фатхуллин, С. А. Трушкин, V. Stolyarov, Н. Н. Бурсов, A. A. Kudryashova, A. Arshinova, T. S. Andreeva, K. V. Iuzhanina
article en
6 citations

Abstract

ABSTRACT We present a study of the multiwavelength (MW) variability of the blazar AO 0235$+$164 based on the radio-to-$\gamma$-ray data covering a long time period from 1997 to 2023. The radio data are represented by the 1–22 GHz measurements from the SAO RAS RATAN-600 radio telescope, the 5 and 8 GHz data from the IAA RAS RT-32 telescopes, and the 37 GHz data from the RT-22 telescope of CrAO RAS. The optical measurements in the R-band were collected with the SAO RAS 1-m Zeiss-1000 and 0.5-m AS-500/2 telescopes. Additionally, we used the archive data at 230 GHz from the Submillimetre Array and the $\gamma$-ray data in the 0.1–100 GeV band from the Fermi-LAT point source 4FGL-DR2 catalogue. The variability properties during four epochs containing major flares and one epoch of relatively low activity were analysed using the fractional variability indices, discrete correlation functions, Lomb–Scargle periodograms, and structure functions. A significant correlation ($\ge \!2\sigma$) between the radio, optical, and $\gamma$-ray bands is found for all these periods with time delays from 0 to 1.7 yr. The relation between time delay and frequency is described by a linear law with a negative slope of $-10$ d GHz$^{-1}$. The discovered properties of MW variability for the low-activity period and for flaring states suggest that the mechanisms dominating the radio–$\gamma$-ray variations are not substantially different. The detected quasi-periodic oscillations of about 6 and 2 yr are tentative, as the time span of the observations includes fewer than four full cycles for the radio and optical data and only about three cycles for the Fermi-LAT data. These results should be interpreted with caution, given the limited number of observed cycles and the influence of red noise. We used cluster analysis to reliably separate the high and low-activity states and determined statistical differences in the main properties of AO 0235$+$164 non-thermal emission. The physical parameters of the radio jet were obtained using the Hedgehog model applied to the average radio spectrum of AO 0235$+$164 in the range 0.1–300 GHz. The effectiveness of replacing electrons with protons in the synchrotron radio emission of relativistic jets is shown for describing the nature of blazars and the generation of high-energy neutrinos.

Monthly Notices of the Royal Astronomical SocietyVol. 535(3)
Russian Academy of Sciences (RU), Moscow Institute of Physics and Technology (RU), St Petersburg University (RU), Kazan Federal University (RU), University of Johannesburg (ZA), University of Cambridge (GB), Special Astrophysical Observatory (RU), Astro Space Center (RU), Bridge University (SS), Institute for Nuclear Research (RU), FZU ‒ Institute of Physics of the Academy of Sciences of the Czech Republic (CZ), Center for Astrophysics Harvard & Smithsonian (US), Institute of Applied Astronomy (RU), Max Planck Institute for Radio Astronomy (DE), Crimean Astrophysical Observatory (UA)
Smithsonian Institution, National Aeronautics and Space Administration, California Institute of Technology, European Commission, National Research Foundation, Academia Sinica, Ministry of Science and Higher Education of the Russian Federation, Jet Propulsion Laboratory, Smithsonian Astrophysical Observatory, H2020 European Research Council
Openalex Percentile: Top 5%
Astrophysics and Cosmic Phenomena
3.96
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