Radio and γ-Ray Variability in Blazar S5 0716+714: A Year-like Quasi-periodic Oscillation in the Radio Light Curve

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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2023-02-01
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en
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Astrophysical Journal, Volume 943, issue 2
Abstract
The nearly 33 yr long-term radio light curve obtained with the Metsähovi Radio Observatory 14 m telescope at 37 GHz and the recent 12.7 yr γ-ray light curve of the blazar S5 0716+714 at 0.1-300 GeV from the Fermi Large Area Telescope (Fermi-LAT) were analyzed by using the Lomb-Scargle periodogram and the weighted wavelet Z-transform techniques. In the radio light curve, we discovered a possible quasi-periodic oscillation (QPO) signal of about 352 ± 23 days at a confidence level of ∼3σ. We recalculated the periodicity and its significance in a chosen time range that has higher variability and denser sampling, and then found that the significance had increased to a confidence level of 99.996% (∼4.1σ). This QPO component was further confirmed by fitting a linear autoregressive integrated moving average model to the selected radio light curve. A possible QPO of 960 ± 80 days at a 99.35% level (∼2.7σ) was found in the γ-ray light curve, which generally agrees with the earlier QPO claims of S5 0716+714. This paper discusses possible mechanisms for this potential year-like QPO. One possibility is a pure geometrical scenario with blobs moving helically inside the jet. Another is a supermassive binary black hole involving a gravitational wave-driven regime. In the latter scenario, we derived a milliparsec separation in the binary system that undergoes coalescence within a century due to the emission of low-frequency gravitational waves.
Description
Funding Information: We sincerely thank the anonymous referee for constructive comments and suggestions that greatly improved this manuscript. This publication makes use of data obtained from Fermi Science Support Center (FSSC), and Metsähovi Radio Observatory, operated by the Aalto University in Finland. The light-curve simulation and significance estimation were performed on the key laboratory of high-density computing, Zhaotong University. This work is supported by the National Natural Science Foundation of China (grant No. 11903028) and the “Yunnan Revitalization Talent Support Program” of Yunnan province, China. Funding Information: We sincerely thank the anonymous referee for constructive comments and suggestions that greatly improved this manuscript. This publication makes use of data obtained from Fermi Science Support Center (FSSC), and Metsähovi Radio Observatory, operated by the Aalto University in Finland. The light-curve simulation and significance estimation were performed on the key laboratory of high-density computing, Zhaotong University. This work is supported by the National Natural Science Foundation of China (grant No. 11903028) and the “Yunnan Revitalization Talent Support Program” of Yunnan province, China. Publisher Copyright: © 2023. The Author(s). Published by the American Astronomical Society.
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Li , X P , Yang , H Y , Cai , Y , Lähteenmäki , A , Tornikoski , M , Tammi , J , Suutarinen , S , Yang , H T , Luo , Y H & Wang , L S 2023 , ' Radio and γ-Ray Variability in Blazar S5 0716+714: A Year-like Quasi-periodic Oscillation in the Radio Light Curve ' , Astrophysical Journal , vol. 943 , no. 2 , 157 . https://doi.org/10.3847/1538-4357/acae8c