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Investigating the multiwavelength behaviour of the flat spectrum radio quasar CTA 102 during 2013–2017

Ammando, F. D. and Kiehlmann, S. and Readhead, A. C. S. and Pearson, T. J. (2019) Investigating the multiwavelength behaviour of the flat spectrum radio quasar CTA 102 during 2013–2017. Monthly Notices of the Royal Astronomical Society, 490 (4). pp. 5300-5316. ISSN 0035-8711.

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We present a multiwavelength study of the flat-spectrum radio quasar CTA 102 during 2013–2017. We use radio-to-optical data obtained by the Whole Earth Blazar Telescope, 15 GHz data from the Owens Valley Radio Observatory, 91 and 103 GHz data from the Atacama Large Millimeter Array, near-infrared data from the Rapid Eye Monitor telescope, as well as data from the Swift (optical-UV and X-rays) and Fermi (γ-rays) satellites to study flux and spectral variability and the correlation between flux changes at different wavelengths. Unprecedented γ-ray flaring activity was observed during 2016 November–2017 February, with four major outbursts. A peak flux of (2158 ± 63) × 10⁻⁸ ph cm⁻² s⁻¹, corresponding to a luminosity of (2.2 ± 0.1) × 10⁵⁰ erg s⁻¹, was reached on 2016 December 28. These four γ-ray outbursts have corresponding events in the near-infrared, optical, and UV bands, with the peaks observed at the same time. A general agreement between X-ray and γ-ray activity is found. The γ-ray flux variations show a general, strong correlation with the optical ones with no time lag between the two bands and a comparable variability amplitude. This γ-ray/optical relationship is in agreement with the geometrical model that has successfully explained the low-energy flux and spectral behaviour, suggesting that the long-term flux variations are mainly due to changes in the Doppler factor produced by variations of the viewing angle of the emitting regions. The difference in behaviour between radio and higher energy emission would be ascribed to different viewing angles of the jet regions producing their emission.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Ammando, F. D.0000-0001-7618-7527
Kiehlmann, S.0000-0001-6314-9177
Readhead, A. C. S.0000-0001-9152-961X
Pearson, T. J.0000-0001-5213-6231
Additional Information:© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model ( Accepted 2019 October 1. Received 2019 October 1; in original form 2019 March 11. Published: 09 October 2019. The data collected by the WEBT collaboration are stored in the WEBT archive at the Osservatorio Astrofisico di Torino - INAF (; for questions regarding their availability, contact the WEBT President Massimo Villata ( We acknowledge financial contribution from the agreement ASI-INAF n. 2017-14-H.0 and from the contract PRIN-SKA-CTA-INAF 2016. This research was partially supported by the Bulgarian National Science Fund of the Ministry of Education and Science under grants DN 08-1/2016, DN 18-13/2017, and KP-06-H28/3 (2018). The Skinakas Observatory is a collaborative project of the University of Crete, the Foundation for Research and Technology – Hellas, and the Max-Planck-Institut für Extraterrestrische Physik. The Abastumani team acknowledges financial support by the Shota Rustaveli National Science Foundation under contract FR/217554/16. The St. Petersburg University team acknowledges support from Russian Science Foundation grant 17-12-01029. GD and OV gratefully acknowledge the observing grant support from the Institute of Astronomy and Rozhen National Astronomical Observatory, Bulgarian Academy of Sciences, via bilateral joint research project ‘Study of ICRF radio-sources and fast variable astronomical objects’ (head - G.Damljanovic). This work is a part of the Projects No. 176011 (‘Dynamics and Kinematics of Celestial Bodies and Systems’), No. 176004 (‘Stellar Physics’), and No. 176021 (‘Visible and Invisible Matter in Nearby Galaxies: Theory and Observations’) supported by the Ministry of Education, Science and Technological Development of the Republic of Serbia. JE is indebted to DGAPA (Universidad Nacional Autónoma de México) for financial support, PAPIIT project IN114917. The Submillimeter Array is a joint project between the Smithsonian Astrophysical Observatory and the Academia Sinica Institute of Astronomy and Astrophysics and is funded by the Smithsonian Institution and the Academia Sinica. Data from the Steward Observatory blazar monitoring project were used. This program is supported by NASA/Fermi Guest Investigator grants NNX12AO93G and NNX15AU81G. We acknowledge support by Bulgarian National Science Programme ‘Young Scientists and Postdoctoral Students 2019’, Bulgarian National Science Fund under grant DN18-10/2017 and National RI Roadmap Projects DO1-157/28.08.2018 and DO1-153/28.08.2018 of the Ministry of Education and Science of the Republic of Bulgaria. This publication makes use of data obtained at Metsähovi Radio Observatory, operated by Aalto University in Finland. The Astronomical Observatory of the Autonomous Region of the Aosta Valley (OAVdA) is managed by the Fondazione Clment Fillietroz-ONLUS, which is supported by the Regional Government of the Aosta Valley, the Town Municipality of Nus and the ‘Unit des Communes valdtaines Mont-milius’. The research at the OAVdA was partially funded by two ‘Research and Education’ grants from Fondazione CRT. RR acknowledges support from CONICYT project Basal AFB-170002. MM and TM acknowledge support through the Russian Government Program of Competitive Growth of Kazan Federal University. The Fermi LAT Collaboration acknowledges generous ongoing support from a number of agencies and institutes that have supported both the development and the operation of the LAT as well as scientific data analysis. These include the National Aeronautics and Space Administration and the Department of Energy in the United States, the Commissariat à l’Energie Atomique and the Centre National de la Recherche Scientifique / Institut National de Physique Nucléaire et de Physique des Particules in France, the Agenzia Spaziale Italiana and the Istituto Nazionale di Fisica Nucleare in Italy, the Ministry of Education, Culture, Sports, Science and Technology (MEXT), High Energy Accelerator Research Organization (KEK) and Japan Aerospace Exploration Agency (JAXA) in Japan, and the K. A. Wallenberg Foundation, the Swedish Research Council and the Swedish National Space Board in Sweden. Additional support for science analysis during the operations phase is gratefully acknowledged from the Istituto Nazionale di Astrofisica in Italy and the Centre National d’Études Spatiales in France. This work performed in part under DOE Contract DE-AC02-76SF00515. The OVRO 40-m monitoring program is supported in part by NASA grants NNX08AW31G, NNX11A043G, and NNX14AQ89G, and NSF grants AST-0808050 and AST-1109911. We thank the Swift team for making these observations possible, the duty scientists, and science planners. This research has made use 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. FD thanks S. Covino for his help with the REM data reduction. This research has made use of data obtained from the high-energy Astrophysics Science Archive Research Center (HEASARC) provided by NASA’s Goddard Space Flight Center. We regret to mention that K. Kuratov passed away while this paper was under review.
Group:Astronomy Department
Funding AgencyGrant Number
Agenzia Spaziale Italiana (ASI)2017-14-H.0
Istituto Nazionale di Astrofisica (INAF)UNSPECIFIED
Ministry of Education and Science (Bulgaria)DN 08-1/2016
Ministry of Education and Science (Bulgaria)DN 18-13/2017
Ministry of Education and Science (Bulgaria)KP-06-H28/3
Shota Rustaveli National Science FoundationFR/217554/16
Russian Science Foundation17-12-01029
Institute of AstronomyUNSPECIFIED
Rozhen National Astronomical ObservatoryUNSPECIFIED
Bulgarian Academy of SciencesUNSPECIFIED
Ministry of Education, Science and Technological Development (Serbia)176011
Ministry of Education, Science and Technological Development (Serbia)176004
Ministry of Education, Science and Technological Development (Serbia)176021
Universidad Nacional Autónoma de México (UNAM)IN114917
Smithsonian InstitutionUNSPECIFIED
Academia SinicaUNSPECIFIED
Bulgarian National Science FundDN18-10/2017
Ministry of Education and Science (Bulgaria)DO1-157/28.08.2018
Ministry of Education and Science (Bulgaria)DO1-153/28.08.2018
Kazan Federal UniversityUNSPECIFIED
Department of Energy (DOE)DE-AC02-76SF00515
Subject Keywords:radiation mechanisms: non-thermal – galaxies: individual: CTA 102 – galaxies: jets – galaxies: nuclei – gamma-rays: general
Issue or Number:4
Record Number:CaltechAUTHORS:20200110-132616951
Persistent URL:
Official Citation:F D’Ammando, C M Raiteri, M Villata, J A Acosta-Pulido, I Agudo, A A Arkharov, R Bachev, G V Baida, E Benítez, G A Borman, W Boschin, V Bozhilov, M S Butuzova, P Calcidese, M I Carnerero, D Carosati, C Casadio, N Castro-Segura, W-P Chen, G Damljanovic, A Di Paola, J Echevarría, N V Efimova, Sh A Ehgamberdiev, C Espinosa, A Fuentes, A Giunta, J L Gómez, T S Grishina, M A Gurwell, D Hiriart, H Jermak, B Jordan, S G Jorstad, M Joshi, G N Kimeridze, E N Kopatskaya, K Kuratov, O M Kurtanidze, S O Kurtanidze, A Lähteenmäki, V M Larionov, E G Larionova, L V Larionova, C Lázaro, C S Lin, M P Malmrose, A P Marscher, K Matsumoto, B McBreen, R Michel, B Mihov, M Minev, D O Mirzaqulov, S N Molina, J W Moody, D A Morozova, S V Nazarov, A A Nikiforova, M G Nikolashvili, J M Ohlert, N Okhmat, E Ovcharov, F Pinna, T A Polakis, C Protasio, T Pursimo, F J Redondo-Lorenzo, N Rizzi, G Rodriguez-Coira, K Sadakane, A C Sadun, M R Samal, S S Savchenko, E Semkov, L Sigua, B A Skiff, L Slavcheva-Mihova, P S Smith, I A Steele, A Strigachev, J Tammi, C Thum, M Tornikoski, Yu V Troitskaya, I S Troitsky, A A Vasilyev, O Vince, (the WEBT Collaboration), T Hovatta, S Kiehlmann, W Max-Moerbeck, A C S Readhead, R Reeves, T J Pearson, (the OVRO Team), T Mufakharov, Yu V Sotnikova, M G Mingaliev, Investigating the multiwavelength behaviour of the flat spectrum radio quasar CTA 102 during 2013–2017, Monthly Notices of the Royal Astronomical Society, Volume 490, Issue 4, December 2019, Pages 5300–5316,
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ID Code:100627
Deposited By: Tony Diaz
Deposited On:11 Jan 2020 00:47
Last Modified:11 Jan 2020 00:47

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