Extreme photometric and polarimetric variability of blazar S4 0954+65 at its maximum optical and γ-ray brightness levels
C. M. RaiteriINAF, Osservatorio Astrofisico di Torino , via Osservatorio 20, I-10025 Pino Torinese , ItalyM. VillataINAF, Osservatorio Astrofisico di Torino , via Osservatorio 20, I-10025 Pino Torinese , ItalyM. I. CarnereroINAF, Osservatorio Astrofisico di Torino , via Osservatorio 20, I-10025 Pino Torinese , ItalyС. С. СавченкоPulkovo Observatory , St. Petersburg 196140 , RussiaS. O. KurtanidzeAbastumani Observatory , Mt. Kanobili, 0301 Abastumani , GeorgiaVasily Vasilievich VlasyukSpecial Astrophysical Observatory of Russian Academy of Sciences , Nyzhnij Arkhyz, Karachai-Circassia 369167 , RussiaAlessandro MarchiniAstronomical Observatory, University of Siena , I-53100 Siena , ItalyKatsura MatsumotoAstronomical Institute, Osaka Kyoiku University , Osaka 582-8582 , JapanC. LoreyM. D. JonerDepartment of Physics and Astronomy , N283 ESC, Brigham Young University, Provo, UT 84602 , USAK. GazeasSection of Astrophysics, Astronomy and Mechanics, Department of Physics, National and Kapodistrian University of Athens , GR-15784 Zografos, Athens , GreeceD. CarosatiEPT Observatories , Tijarafe, La Palma, E-38780, , SpainD. O. MirzaqulovUlugh Beg Astronomical Institute , Astronomy Street 33, Tashkent 100052 , UzbekistanJ. A. Acosta‐PulidoDepartamento de Astrofísica, Universidad de La Laguna (ULL) , E-38206 La Laguna, Tenerife , SpainI. AgudoInstituto de Astrofísica de Andalucía (CSIC) , Apartado 3004, E-18080 Granada , SpainR. BachevInstitute of Astronomy and National Astronomical Observatory, Bulgarian Academy of Sciences , 72 Tsarigradsko shosse Blvd., 1784 Sofia , BulgariaE. BenítezInstituto de Astronomía, Universidad Nacional Autónoma de México , AP 70-264, CDMX 04510 , MexicoГ. А. БорманCrimean Astrophysical Observatory RAS , P/O Nauchny 298409 , RussiaP. CalcideseOsservatorio Astronomico della Regione Autonoma Valle d’Aosta , I-11020 Nus , ItalyWen-Ping ChenInstitute of Astronomy, National Central University , Taoyuan 32001 , TaiwanG. DamljanovićAstronomical Observatory , Volgina 7, 11060 Belgrade , SerbiaSh. A. EhgamberdievNational University of Uzbekistan , Tashkent 100174 , UzbekistanDominik ElsässerHans-Haffner-Sternwarte (Hettstadt) , Naturwissenschaftliches Labor für Schüler, Friedrich-Koenig-Gymnasium, D-97082 Würzburg , GermanyM. FeigeA. FrascaINAF, Osservatorio Astrofisico di Catania , Via S. Sofia 78, I-95123 Catania , ItalyHaritma GaurAryabhatta Research Institute of Observational Sciences (ARIES) , Manora Peak, Nainital 263001 , IndiaT. S. GrishinaSaint Petersburg State University , 7/9 Universitetskaya nab., St. Petersburg 199034 , RussiaAlok C. GuptaAryabhatta Research Institute of Observational Sciences (ARIES) , Manora Peak, Nainital 263001 , IndiaD. HiriartInstituto de Astronomía, Universidad Nacional Autónoma de México , AP 106, Ensenada 22800, Baja California , MexicoM. HollandDepartment of Physics and Astronomy , N283 ESC, Brigham Young University, Provo, UT 84602 , USAB HorstS. IbryamovDepartment of Physics and Astronomy, Faculty of Natural Sciences, University of Shumen , 115, Universitetska Str., 9712 Shumen , BulgariaR. Z. IvanidzeAbastumani Observatory , Mt. Kanobili, 0301 Abastumani , GeorgiaJennifer JensenDepartment of Physics and Astronomy , N283 ESC, Brigham Young University, Provo, UT 84602 , USAV JitheshDepartment of Physics and Electronics, CHRIST (Deemed to be University) , Hosur Main Road, Bengaluru 560029 , IndiaM. D. JovanovićAstronomical Observatory , Volgina 7, 11060 Belgrade , SerbiaS. KiehlmannDepartment of Physics, University of Crete , Voutes University Campus, GR-70013 Heraklion , GreeceG. N. KimeridzeAbastumani Observatory , Mt. Kanobili, 0301 Abastumani , GeorgiaShubham KishoreAryabhatta Research Institute of Observational Sciences (ARIES) , Manora Peak, Nainital 263001 , IndiaE. N. KopatskayaSaint Petersburg State University , 7/9 Universitetskaya nab., St. Petersburg 199034 , RussiaO. M. KurtanidzeAbastumani Observatory , Mt. Kanobili, 0301 Abastumani , GeorgiaЕ. Г. ЛарионоваSaint Petersburg State University , 7/9 Universitetskaya nab., St. Petersburg 199034 , RussiaH. C. LinInstitute of Astronomy, National Central University , Taoyuan 32001 , TaiwanK. MannheimHans-Haffner-Sternwarte (Hettstadt) , Naturwissenschaftliches Labor für Schüler, Friedrich-Koenig-Gymnasium, D-97082 Würzburg , GermanyC. MarinelliDip. di Scienze Fisiche, della Terra e dell’Ambiente, Università di Siena , via Roma 56, I-53100 Siena , ItalyJ. Moreira ReyesDepartment of Physics, Astronomy and Geophysics, Connecticut College , New London, CT 06320 , USAD. A. MorozovaSaint Petersburg State University , 7/9 Universitetskaya nab., St. Petersburg 199034 , RussiaM. G. NikolashviliAbastumani Observatory , Mt. Kanobili, 0301 Abastumani , GeorgiaDavid ReinhartHans-Haffner-Sternwarte (Hettstadt) , Naturwissenschaftliches Labor für Schüler, Friedrich-Koenig-Gymnasium, D-97082 Würzburg , GermanyF. D. RomanovAAVSO observer , RussiaE. SemkovInstitute of Astronomy and National Astronomical Observatory, Bulgarian Academy of Sciences , 72 Tsarigradsko shosse Blvd., 1784 Sofia , BulgariaJ SeufertEkaterina V. ShishkinaSaint Petersburg State University , 7/9 Universitetskaya nab., St. Petersburg 199034 , RussiaL. A. SiguaAbastumani Observatory , Mt. Kanobili, 0301 Abastumani , GeorgiaRaphael SkalidisOwens Valley Radio Observatory, California Institute of Technology , MC 249-17, Pasadena, CA 91125 , USAO. I. SpiridonovaSpecial Astrophysical Observatory of Russian Academy of Sciences , Nyzhnij Arkhyz, Karachai-Circassia 369167 , RussiaM. StojanovićAstronomical Observatory , Volgina 7, 11060 Belgrade , SerbiaA. StrigachevInstitute of Astronomy and National Astronomical Observatory, Bulgarian Academy of Sciences , 72 Tsarigradsko shosse Blvd., 1784 Sofia , BulgariaYu. V. TroitskayaSaint Petersburg State University , 7/9 Universitetskaya nab., St. Petersburg 199034 , RussiaI. S. TroitskiySaint Petersburg State University , 7/9 Universitetskaya nab., St. Petersburg 199034 , RussiaAn-Li TsaiInstitute of Astronomy, National Central University , Taoyuan 32001 , TaiwanA. A. VasilyevSaint Petersburg State University , 7/9 Universitetskaya nab., St. Petersburg 199034 , RussiaO. VinceAstronomical Observatory , Volgina 7, 11060 Belgrade , SerbiaK VrontakiSection of Astrophysics, Astronomy and Mechanics, Department of Physics, National and Kapodistrian University of Athens , GR-15784 Zografos, Athens , GreeceKiran WaniAryabhatta Research Institute of Observational Sciences (ARIES) , Manora Peak, Nainital 263001 , IndiaDuncan J. WattsDepartment of Physics and Astronomy , N283 ESC, Brigham Young University, Provo, UT 84602 , USAА. В. ЖовтанCrimean Astrophysical Observatory RAS , P/O Nauchny 298409 , Russia
ABI
Аннотация
ABSTRACT In 2022 the BL Lac object S4 0954+65 underwent a major variability phase, reaching its historical maximum brightness in the optical and γ-ray bands. We present optical photometric and polarimetric data acquired by the Whole Earth Blazar Telescope (WEBT) Collaboration from 2022 April 6 to July 6. Many episodes of unprecedented fast variability were detected, implying an upper limit to the size of the emitting region as low as $10^{-4}$ parsec. The WEBT data show rapid variability in both the degree and angle of polarization. We analyse different models to explain the polarization behaviour in the framework of a twisting jet model, which assumes that the long-term trend of the flux is produced by variations in the emitting region viewing angle. All the models can reproduce the average trend of the polarization degree, and can account for its general anticorrelation with the flux, but the dispersion of the data requires the presence of intrinsic mechanisms, such as turbulence, shocks, or magnetic reconnection. The WEBT optical data are compared to γ-ray data from the Fermi satellite. These are analysed with both fixed and adaptive binning procedures. We show that the strong correlation between optical and γ-ray data without measurable delay assumes different slopes in faint and high brightness states, and this is compatible with a scenario where in faint states we mainly see the imprint of the geometrical effects, while in bright states the synchrotron self-Compton process dominates.
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Показатели — AkademScholar · Скоро