1. The complex variability of blazars: time-scales and periodicity analysis in S4 0954+65
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A. A. Nikiforova, Efthalia Traianou, Sergey S. Savchenko, J. Escudero, L. V. Larionova, T. S. Andreeva, V. Bozhilov, W. J. Hou, An-Li Tsai, Carolina Casadio, Anne Lähteenmäki, Ioannis Myserlis, Merja Tornikoski, A. Fuentes, J. A. Acosta-Pulido, I. Agudo, S. O. Kurtanidze, A. A. Arkharov, F. D'Ammando, M. I. Carnerero, M. Hart, D. Ivanov, Goran Damljanović, Evgeni Semkov, M. Stojanovic, J. Otero-Santos, Y. V. Troitskaya, I. Rahimov, Wen Ping Chen, E. N. Kopatskaya, D. Shakhovskoy, Alok C. Gupta, Rumen Bachev, D. Carosati, A. Strigachev, Antoniya Valcheva, Elena G. Larionova, M. Nakamura, M. G. Nikolashvili, Alan P. Marscher, G. A. Borman, Valeri M. Larionov, N. Marchili, Z. R. Weaver, T. Pursimo, Marcello Giroletti, Marco Berton, C. Konstantopoulou, Simona Righini, O. M. Kurtanidze, I. Björklund, T. Sakamoto, C. M. Raiteri, M. Villata, T. S. Grishina, Evgeni Ovcharov, M. Minev, J. Y. Kim, E. Zaharieva, Vladimir A. Hagen-Thorn, S. G. Jorstad, Clemens Thum, D. A. Morozova, O. Vince, A. A. Vasilyev, G. Markovic, Givi N. Kimeridze, Lorand A. Sigua, Erika Benítez, David Hiriart, I. S. Troitskiy, National Aeronautics and Space Administration (US), Ministry of Education, Science and Technological Development (Serbia), Bulgarian National Science Fund, Shota Rustaveli National Science Foundation, Ministerio de Ciencia, Innovación y Universidades (España), Ministerio de Economía y Competitividad (España), National Institute for Astrophysics, St. Petersburg State University, Boston University, Instituto de Astrofísica de Canarias, CSIC, Russian Academy of Sciences, RAS - Pulkovo Astronomical Observatory, Bulgarian Academy of Sciences, Universidad Nacional Autónoma de México, Metsähovi Radio Observatory, Department of Electronics and Nanoengineering, Sofia University St. Kliment Ohridski, EPT Observatories, Institute of Electronic Structure and Laser, National Central University, University of Belgrade, Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna, Aryabhatta Research Institute of Observational Sciences, Korea Astronomy and Space Science Institute, Georgian National Academy of Sciences, Nordic Optical Telescope, Max Planck Institute for Radio Astronomy, Aoyama Gakuin University, IRAM, Aalto-yliopisto, and Aalto University
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individual: S4 0954+65 [BL Lacertae objects] ,active [Galaxies] ,BL Lacertae objects: individual: S4 0954+65 ,Astrophysics::High Energy Astrophysical Phenomena ,FOS: Physical sciences ,Library science ,7. Clean energy ,01 natural sciences ,IRAM 30m telescope ,Observatory ,0103 physical sciences ,Bulgarian ,010303 astronomy & astrophysics ,High Energy Astrophysical Phenomena (astro-ph.HE) ,Physics ,general [BL Lacertae objects] ,010308 nuclear & particles physics ,Astronomy and Astrophysics ,Galaxies: active ,BL Lacertae objects: general ,Astrophysics - Astrophysics of Galaxies ,language.human_language ,Joint research ,Galaxies: jets ,13. Climate action ,Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,language ,jets [Galaxies] ,Christian ministry ,Astrophysics - High Energy Astrophysical Phenomena ,Administration (government) - Abstract
Full list of authors: Raiteri, C. M.; Villata, M.; Larionov, V. M.; Jorstad, S. G.; Marscher, A. P.; Weaver, Z. R.; Acosta-Pulido, J. A.; Agudo, I.; Andreeva, T.; Arkharov, A.; Bachev, R.; Benítez, E.; Berton, M.; Björklund, I.; Borman, G. A.; Bozhilov, V.; Carnerero, M. I.; Carosati, D.; Casadio, C.; Chen, W. P. Damljanovic, G.; D'Ammando, F.; Escudero, J.; Fuentes, A.; Giroletti, M.; Grishina, T. S.; Gupta, A. C.; Hagen-Thorn, V. A.; Hart, M.; Hiriart, D.; Hou, W. -J.; Ivanov, D.; Kim, J. -Y.; Kimeridze, G. N.; Konstantopoulou, C.; Kopatskaya, E. N.; Kurtanidze, O. M.; Kurtanidze, S. O.; Lähteenmäki, A.; Larionova, E. G.; Larionova, L. V.; Marchili, N.; Markovic, G.; Minev, M.; Morozova, D. A.; Myserlis, I.; Nakamura, M.; Nikiforova, A. A.; Nikolashvili, M. G.; Otero-Santos, J.; Ovcharov, E.; Pursimo, T.; Rahimov, I.; Righini, S.; Sakamoto, T.; Savchenko, S. S.; Semkov, E. H.; Shakhovskoy, D.; Sigua, L. A.; Stojanovic, M.; Strigachev, A.; Thum, C.; Tornikoski, M.; Traianou, E.; Troitskaya, Y. V.; Troitskiy, I. S.; Tsai, A.; Valcheva, A.; Vasilyev, A. A.; Vince, O.; Zaharieva, E., Among active galactic nuclei, blazars show extreme variability properties. We here investigate the case of the BL Lac object S4 0954+65 with data acquired in 2019-2020 by the Transiting Exoplanet Survey Satellite (TESS) and by the Whole Earth Blazar Telescope (WEBT) Collaboration. The 2-min cadence optical light curves provided by TESS during three observing sectors of nearly 1 month each allow us to study the fast variability in great detail. We identify several characteristic short-term time-scales, ranging from a few hours to a few days. However, these are not persistent, as they differ in the various TESS sectors. The long-term photometric and polarimetric optical and radio monitoring undertaken by the WEBT brings significant additional information, revealing that (i) in the optical, long-term flux changes are almost achromatic, while the short-term ones are strongly chromatic; (ii) the radio flux variations at 37 GHz follow those in the optical with a delay of about 3 weeks; (iii) the range of variation of the polarization degree and angle is much larger in the optical than in the radio band, but the mean polarization angles are similar; (iv) the optical long-term variability is characterized by a quasi-periodicity of about 1 month. We explain the source behaviour in terms of a rotating inhomogeneous helical jet, whose pitch angle can change in time. © 2021 The Author(s)., This paper includes data collected by the TESS mission. Funding for the TESS mission is provided by the NASA Explorer Program. Partly based on observations made with the Nordic Optical Telescope, owned in collaboration by the University of Turku and Aarhus University, and operated jointly by Aarhus University, the University of Turku and the University of Oslo, representing Denmark, Finland and Norway, the University of Iceland and Stockholm University at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias. This article is partly based on observations made in the Observatorios de Canarias del IAC with the Liverpool telescope operated on the island of La Palma by the Liverpool John Moores University in the Observatorio del Roque de Los Muchachos. This article is partly based on observations made with the LCOGT Telescopes, one of whose nodes is located at the Observatorios de Canarias del IAC on the island of Tenerife in the Observatorio del Teide. This article is partly based on observations made with the IAC-80 operated on the island of Tenerife by the Instituto de Astrofisica de Canarias in the Spanish Observatorio del Teide. Many thanks are due to the IAC support astronomers and telescope operators for supporting the observations at the IAC-80 telescope. This publication makes use of data obtained at Metsähovi Radio Observatory, operated by Aalto University in Finland. This research has made use of NASA’s Astrophysics Data System and of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. The research at Boston University was supported by NASA grants 80NSSC20K1566 (Fermi Guest Investigator Program) and 80NSSC21K0243 (TESS Guest Investigator Program). This study was based (in part) on observations conducted using the 1.8 m Perkins Telescope Observatory (PTO) in Arizona (USA), which is owned and operated by Boston University. GD, MS, GM, and OV acknowledge the observing grant support from the Institute of Astronomy and Rozhen NAO BAS through the bilateral joint research project ‘Gaia Celestial Reference Frame (CRF) and fast variable astronomical objects’ (2020–2022, leader is G.Damljanovic), and support by the Ministry of Education, Science and Technological Development of the Republic of Serbia (contract No 451-03-68/2020-14/200002) This research was partially supported by the Bulgarian National Science Fund of the Ministry of Education and Science under grants DN 18-13/2017, KP-06-H28/3 (2018), KP-06-H38/4 (2019), and KP-06-KITAJ/2 (2020). SOK acknowledges financial support by Shota Rustaveli National Science Foundation of Georgia under contract PHDF-18-354 EB acknowledges support from DGAPA-PAPIIT GRANT IN113320. This work is partly based upon observations carried out at the Observatorio Astronómico Nacional on the Sierra San Pedro Mártir (OAN- SPM), Baja California, Mexico. We acknowledge support by Bulgarian National Science Fund under grant DN18-10/2017 and National RI Roadmap Project DO1-383/18.12.2020 of the Ministry of Education and Science of the Republic of Bulgaria. IA acknowledges financial support from the Spanish ‘Ministerio de Ciencia e Innovación’ (MCINN) through the ‘Center of Excellence Severo Ochoa’ award for the Instituto de Astrofísica de Andalucía-CSIC (SEV-2017-0709). Acquisition and reduction of the POLAMI data was supported in part by MICINN through grants AYA2016-80889-P and PID2019-107847RB-C44. The POLAMI observations were carried out at the IRAM 30m Telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain).
- Published
- 2021