A1 Refereed original research article in a scientific journal

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




AuthorsLi Xiao-Pan, Yang Hai-Yan, Cai Yan, Lähteenmäki Anne, Tornikoski Merja, Tammi Joni, Suutarinen Sofia, Yang Hai-Tao, Luo Yu-Hui, Wang Li-Sha

PublisherIOP Publishing Ltd

Publication year2023

JournalAstrophysical Journal

Journal name in sourceASTROPHYSICAL JOURNAL

Journal acronymASTROPHYS J

Article number157

Volume943

Number of pages9

ISSN0004-637X

eISSN1538-4357

DOIhttps://doi.org/10.3847/1538-4357/acae8c

Web address https://doi.org/10.3847/1538-4357/acae8c

Self-archived copy’s web addresshttps://research.utu.fi/converis/portal/detail/Publication/178966415


Abstract

The nearly 33 yr long-term radio light curve obtained with the Metsahovi Radio Observatory 14 m telescope at 37 GHz and the recent 12.7 yr gamma-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 similar to 3 sigma. 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 gamma-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.


Downloadable publication

This is an electronic reprint of the original article.
This reprint may differ from the original in pagination and typographic detail. Please cite the original version.





Last updated on 2024-26-11 at 21:06