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Published June 2020 | Accepted Version + Published
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Unraveling the Complex Behavior of Mrk 421 with Simultaneous X-Ray and VHE Observations during an Extreme Flaring Activity in 2013 April

Acciari, V. A. ORCID icon
Ansoldi, S. ORCID icon
Antonelli, L. A. ORCID icon
Arbet Engels, A. ORCID icon
Baack, D. ORCID icon
Babić, A. ORCID icon
Banerjee, B. ORCID icon
Barres de Almeida, U. ORCID icon
Barrio, J. A. ORCID icon
Becerra González, J. ORCID icon
Bednarek, W. ORCID icon
Bellizzi, L. K.
Bernardini, E. ORCID icon
Berti, A. ORCID icon
Besenrieder, J.
Bhattacharyya, W. ORCID icon
Bigongiari, C. ORCID icon
Biland, A. ORCID icon
Blanch, O. ORCID icon
Bonnoli, G. ORCID icon
Bošnjak, Ž. ORCID icon
Busetto, G. ORCID icon
Carosi, R. ORCID icon
Ceribella, G.
Cerruti, M. ORCID icon
Chai, Y. ORCID icon
Chilingarian, A. ORCID icon
Cikota, S.
Colak, S. M. ORCID icon
Colin, U.
Colombo, E. ORCID icon
Contreras, J. L. ORCID icon
Cortina, J. ORCID icon
Covino, S. ORCID icon
D'Elia, V. ORCID icon
Da Vela, P.
Dazzi, F. ORCID icon
De Angelis, A. ORCID icon
De Lotto, B. ORCID icon
Del Puppo, F.
Delfino, M. ORCID icon
Delgado, J. ORCID icon
Depaoli, D. ORCID icon
Di Pierro, F. ORCID icon
Di Venere, L. ORCID icon
Do Souto Espiñeira, E. ORCID icon
Dominis Prester, D. ORCID icon
Donini, A. ORCID icon
Dorner, D. ORCID icon
Doro, M. ORCID icon
Elsaesser, D. ORCID icon
Fallah Ramazani, V. ORCID icon
Fattorini, A.
Ferrara, G. ORCID icon
Foffano, L. ORCID icon
Fonseca, M. V. ORCID icon
Font, L. ORCID icon
Fruck, C. ORCID icon
Fukami, S.
García López, R. J. ORCID icon
Garczarczyk, M. ORCID icon
Gasparyan, S.
Gaug, M. ORCID icon
Giglietto, N. ORCID icon
Giordano, F. ORCID icon
Gliwny, P. ORCID icon
Godinović, N. ORCID icon
Green, D. ORCID icon
Hadasch, D. ORCID icon
Hahn, A. ORCID icon
Hassan, T. ORCID icon
Herrera, J. ORCID icon
Hoang, J. ORCID icon
Hrupec, D. ORCID icon
Hütten, M. ORCID icon
Inada, T.
Inoue, S. ORCID icon
Ishio, K.
Iwamura, Y.
Jouvin, L. ORCID icon
Kajiwara, Y.
Kerszberg, D. ORCID icon
Kobayashi, Y.
Kubo, H. ORCID icon
Kushida, J. ORCID icon
Lamastra, A. ORCID icon
Lelas, D. ORCID icon
Leone, F. ORCID icon
Lindfors, E. ORCID icon
Lombardi, S. ORCID icon
Longo, F. ORCID icon
López, M. ORCID icon
López-Coto, R. ORCID icon
López-Oramas, A. ORCID icon
Loporchio, S. ORCID icon
Machado de Oliveira Fraga, B. ORCID icon
Maggio, C. ORCID icon
Majumdar, P. ORCID icon
Makariev, M. ORCID icon
Mallamaci, M. ORCID icon
Maneva, G. ORCID icon
Manganaro, M. ORCID icon
Mannheim, K. ORCID icon
Maraschi, L.
Mariotti, M. ORCID icon
Martínez, M. ORCID icon
Mazin, D. ORCID icon
Mender, S. ORCID icon
Mićanović, S. ORCID icon
Miceli, D. ORCID icon
Miener, T.
Minev, M.
Miranda, J. M. ORCID icon
Mirzoyan, R. ORCID icon
Molina, E. ORCID icon
Moralejo, A. ORCID icon
Morcuende, D. ORCID icon
Moreno, V. ORCID icon
Moretti, E. ORCID icon
Munar-Adrover, P. ORCID icon
Neustroev, V. ORCID icon
Nigro, C. ORCID icon
Nilsson, K. ORCID icon
Ninci, D. ORCID icon
Nishijima, K. ORCID icon
Noda, K. ORCID icon
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Nozaki, S. ORCID icon
Ohtani, Y.
Oka, T. ORCID icon
Otero-Santos, J. ORCID icon
Palatiello, M. ORCID icon
Paneque, D. ORCID icon
Paoletti, R. ORCID icon
Paredes, J. M. ORCID icon
Pavletić, L. ORCID icon
Peñil, P.
Peresano, M. ORCID icon
Persic, M. ORCID icon
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Prandini, E. ORCID icon
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Rhode, W. ORCID icon
Ribó, M. ORCID icon
Rico, J. ORCID icon
Righi, C. ORCID icon
Rugliancich, A. ORCID icon
Saha, L. ORCID icon
Sahakyan, N. ORCID icon
Saito, T.
Sakurai, S.
Satalecka, K. ORCID icon
Schleicher, B.
Schmidt, K. ORCID icon
Schweizer, T. ORCID icon
Sitarek, J.
Šnidarić, I.
Sobczynska, D. ORCID icon
Spolon, A. ORCID icon
Stamerra, A. ORCID icon
Strom, D. ORCID icon
Strzys, M.
Suda, Y. ORCID icon
Surić, T.
Takahashi, M. ORCID icon
Tavecchio, F. ORCID icon
Temnikov, P. ORCID icon
Terzić, T. ORCID icon
Teshima, M.
Torres-Albà, N. ORCID icon
Tosti, L.
van Scherpenberg, J. ORCID icon
Vanzo, G. ORCID icon
Vazquez Acosta, M. ORCID icon
Ventura, S. ORCID icon
Verguilov, V. ORCID icon
Vigorito, C. F. ORCID icon
Vitale, V. ORCID icon
Vovk, I. ORCID icon
Will, M. ORCID icon
Zarić, D. ORCID icon
Petropoulou, M. ORCID icon
Finke, J. ORCID icon
D'Ammando, F. ORCID icon
Baloković, M. ORCID icon
Madejski, G.
Mori, K.
Puccetti, Simonetta
Leto, C.
Perri, M.
Verrecchia, F. ORCID icon
Villata, M. ORCID icon
Raiteri, C. M. ORCID icon
Agudo, I. ORCID icon
Bachev, R.
Berdyugin, A.
Blinov, D. A.
Chanishvili, R.
Chen, W. P.
Chigladze, R.
Damljanovic, G.
Eswaraiah, C.
Grishina, T. S.
Ibryamov, S.
Jordan, B.
Jorstad, S. G. ORCID icon
Joshi, M.
Kopatskaya, E. N.
Kurtanidze, O. M. ORCID icon
Kurtanidze, S. O.
Larionova, E. G.
Larionova, L. V.
Larionov, V. M.
Latev, G.
Lin, H. C.
Marscher, A. P. ORCID icon
Mokrushina, A. A.
Morozova, D. A.
Nikolashvili, M. G.
Semkov, E.
Smith, P. S.
Strigachev, A.
Troitskaya, Yu. V.
Troitsky, I. S.
Vince, O.
Barnes, J.
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Moody, J. W.
Sadun, A. C.
Hovatta, T. ORCID icon
Richards, J. L.
Max-Moerbeck, W. ORCID icon
Readhead, A. C. R. ORCID icon
Lähteenmäki, A.
Tornikoski, M. ORCID icon
Tammi, J.
Ramakrishnan, V.
Reinthal, R.
MAGIC Collaboration

Abstract

We report on a multiband variability and correlation study of the TeV blazar Mrk 421 during an exceptional flaring activity observed from 2013 April 11 to 19. The study uses, among others, data from GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope (WEBT), Swift, Nuclear Spectroscopic Telescope Array (NuSTAR), Fermi Large Area Telescope, Very Energetic Radiation Imaging Telescope Array System (VERITAS), and Major Atmospheric Gamma Imaging Cherenkov (MAGIC). The large blazar activity and the 43 hr of simultaneous NuSTAR and MAGIC/VERITAS observations permitted variability studies on 15 minute time bins over three X-ray bands (3–7 keV, 7–30 keV, and 30–80 keV) and three very-high-energy (VHE; >0.1 TeV) gamma-ray bands (0.2–0.4 TeV, 0.4–0.8 TeV, and >0.8 TeV). We detected substantial flux variations on multi-hour and sub-hour timescales in all of the X-ray and VHE gamma-ray bands. The characteristics of the sub-hour flux variations are essentially energy independent, while the multi-hour flux variations can have a strong dependence on the energy of the X-rays and the VHE gamma-rays. The three VHE bands and the three X-ray bands are positively correlated with no time lag, but the strength and characteristics of the correlation change substantially over time and across energy bands. Our findings favor multi-zone scenarios for explaining the achromatic/chromatic variability of the fast/slow components of the light curves, as well as the changes in the flux–flux correlation on day-long timescales. We interpret these results within a magnetic reconnection scenario, where the multi-hour flux variations are dominated by the combined emission from various plasmoids of different sizes and velocities, while the sub-hour flux variations are dominated by the emission from a single small plasmoid moving across the magnetic reconnection layer.

Additional Information

© 2020 The American Astronomical Society. Received 2019 December 5; revised 2020 January 18; accepted 2020 January 23; published 2020 June 10. The MAGIC collaboration would like to thank the Instituto de Astrofísica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The financial support of the German BMBF and MPG, the Italian INFN and INAF, the Swiss National Fund SNF, the ERDF under the Spanish MINECO (FPA2017-87859-P, FPA2017-85668-P, FPA2017-82729-C6-2-R, FPA2017-82729-C6-6-R, FPA2017-82729-C6-5-R, AYA2015-71042-P, AYA2016-76012-C3-1-P, ESP2017-87055-C2-2-P, and FPA201790566REDC), the Indian Department of Atomic Energy, the Japanese JSPS and MEXT, the Bulgarian Ministry of Education and Science, National RI Roadmap Project DO1-153/28.08.2018 and the Academy of Finland grant No. 320045 is gratefully acknowledged. This work was also supported by the Spanish Centro de Excelencia "Severo Ochoa" SEV-2016-0588 and SEV-2015-0548, and Unidad de Excelencia "María de Maeztu" MDM-2014-0369, by the Croatian Science Foundation (HrZZ) Project IP-2016-06-9782 and the University of Rijeka Project 13.12.1.3.02, by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3, the Polish National Research Centre grant UMO-2016/22/M/ST9/00382, and by the Brazilian MCTIC, CNPq and FAPERJ. 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 made use of data from the NuSTAR mission, a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory, and funded by the National Aeronautics and Space Administration. We thank the NuSTAR Operations, Software, and Calibration teams for support with the execution and analysis of these observations. This research has made use of the NuSTAR Data Analysis Software (NuSTARDAS) jointly developed by the ASI Science Data Center (ASDC; Italy) and the California Institute of Technology (USA). This research has made use of the XRT Data Analysis Software (XRTDAS) developed under the responsibility of the ASI Science Data Center (ASDC), Italy. D.P. and A.B. are grateful to Amy Furniss and Wystan Benbow for providing the VERITAS VHE gamma-ray fluxes and for useful discussions about them. M.P. acknowledges support from the Lyman Jr. Spitzer Postdoctoral Fellowship and NASA Fermi grant No. 80NSSC18K1745, and J.F. is partially supported by NASA under contract S-15633Y. M.B. acknowledges support from NASA Headquarters under the NASA Earth and Space Science Fellowship Program (grant NNX14AQ07H) and the black hole Initiative at Harvard University, which is funded in part by the Gordon and Betty Moore Foundation (grant GBMF8273) and in part by the John Templeton Foundation. This research was partially supported by the Bulgarian National Science Fund of the Ministry of Education and Science under grants DN 18-13/2017, DN 18-10/2017, KP-06-H28/3 (2018), and KP-06-PN38/1 (2019), as well as for the Spanish MIMECO (AYA2016-80889-P, RYC-2013-14511) and the IAA-CSIC "Severo Ochoa" program SEV-2017-0709. The St. Petersburg University team acknowledges support from Russian Science Foundation grant 17-12-01029. The Abastumani team acknowledges financial support of the project FR/638/6-320/12 by the Shota Rustaveli National Science Foundation under contract 31/77. T.G. acknowledges support from Istanbul University (Project numbers 49429 and 48285), Bilim Akademisi (BAGEP program), and TUBITAK (project numbers 13AT100-431, 13AT100-466, and 13AT60-430). The Boston University effort was supported in part by NASA grants NNX12AO90G and NNX14AQ58G. Data from the Steward Observatory spectropolarimetric monitoring project were used in this paper. This program is supported by Fermi Guest Investigator grants NNX08AW56G, NNX09AU10G, NNX12AO93G, and NNX15AU81G. The OVRO 40 m monitoring program is supported in part by NASA grants NNX08AW31G and NNX11A043G and NSF grants AST-0808050 and AST-1109911. The Metsähovi team acknowledges the support from the Academy of Finland to our observing projects (numbers 212656, 210338, 121148, and others). W.M. acknowledges support from CONICYT project Basal AFB-170002.

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Created:
August 22, 2023
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October 20, 2023