Investigation of the correlation patterns and the Compton dominance variability of Mrk 421 in 2017

Journal
Date Issued
2021
Author(s)
MAGIC Collaboration
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Acciari, V. A.
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Ansoldi, S.
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Arbet Engels, A.
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Artero, M.
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Asano, K.
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Babić, A.
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Baquero, A.
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Barres de Almeida, U.
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Barrio, J. A.
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Majumdar, P.
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Makariev, M.
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Mallamaci, M.
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Maneva, G.
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Manganaro, M.
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Maraschi, L.
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Mariotti, M.
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Martínez, M.
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Mazin, D.
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Menchiari, S.
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Batković, I.
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Mender, S.
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Mićanović, S.
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Miceli, D.
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Miener, T.
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Minev, M.
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Miranda, J. M.
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Mirzoyan, R.
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Molina, E.
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Moralejo, A.
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Morcuende, D.
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Becerra González, J.
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Moreno, V.
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Moretti, E.
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Neustroev, V.
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Nigro, C.
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Nilsson, K.
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Nishijima, K.
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Noda, K.
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Nozaki, S.
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Ohtani, Y.
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Oka, T.
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Bednarek, W.
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Otero-Santos, J.
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Palatiello, M.
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Paneque, D.
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Paoletti, R.
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Paredes, J. M.
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Pavletić, L.
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Peñil, P.
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Perennes, C.
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Bellizzi, L.
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Prada Moroni, P. G.
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Priyadarshi, C.
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Puljak, I.
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Ribó, M.
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Rico, J.
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Rugliancich, A.
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Saha, L.
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Sahakyan, N.
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Bernardini, E.
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Saito, T.
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Sakurai, S.
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Satalecka, K.
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Schmidt, K.
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Schweizer, T.
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Sitarek, J.
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Šnidarić, I.
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Sobczynska, D.
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Spolon, A.
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Bernardos, M.
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Strom, D.
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Strzys, M.
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Suda, Y.
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Surić, T.
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Takahashi, M.
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Temnikov, P.
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Terzić, T.
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Teshima, M.
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Berti, A.
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Tosti, L.
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Truzzi, S.
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Ubach, S.
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van Scherpenberg, J.
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Vanzo, G.
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Vazquez Acosta, M.
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Ventura, S.
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Verguilov, V.
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Vigorito, C. F.
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Besenrieder, J.
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Vitale, V.
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Vovk, I.
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Will, M.
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Wunderlich, C.
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Zarić, D.
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FACT Collaboration
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Baack, D.
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Balbo, M.
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Biederbeck, N.
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Biland, A.
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Bhattacharyya, W.
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Bretz, T.
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Buss, J.
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Dorner, D.
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Eisenberger, L.
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Elsaesser, D.
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Hildebrand, D.
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Iotov, R.
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Mannheim, K.
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Neise, D.
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Noethe, M.
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Paravac, A.
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Rhode, W.
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Schleicher, B.
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Sliusar, V.
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Walter, R.
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Horan, D.
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Lien, A. Y.
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Baloković, M.
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Madejski, G. M.
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Blanch, O.
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Leto, C.
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Lähteenmäki, A.
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Tornikoski, M.
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Ramakrishnan, V.
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Järvelä, E.
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Vera, R. J. C.
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Chamani, W.
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Bošnjak, Ž.
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Gupta, A. C.
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Pandey, A.
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Fuentes, A.
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Agudo, I.
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Casadio, C.
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Semkov, E.
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Ibryamov, S.
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Marchini, A.
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Bachev, R.
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Busetto, G.
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Strigachev, A.
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Ovcharov, E.
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Bozhilov, V.
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Valcheva, A.
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Zaharieva, E.
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Damljanovic, G.
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Vince, O.
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Larionov, V. M.
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Borman, G. A.
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Grishina, T. S.
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Carosi, R.
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Hagen-Thorn, V. A.
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Kopatskaya, E. N.
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Larionova, E. G.
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Larionova, L. V.
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Morozova, D. A.
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Nikiforova, A. A.
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Savchenko, S. S.
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Troitskiy, I. S.
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Troitskaya, Y. V.
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Vasilyev, A. A.
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Ceribella, G.
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Merkulova, O. A.
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Chen, W. P.
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Samal, M.
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Lin, H. C.
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Moody, J. W.
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Sadun, A. C.
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Jorstad, S. G.
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Marscher, A. P.
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Weaver, Z. R.
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Feige, M.
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Cerruti, M.
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Kania, J.
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Kopp, M.
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Kunkel, L.
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Reinhart, D.
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Scherbantin, A.
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Schneider, L.
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Lorey, C.
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Acosta-Pulido, J. A.
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Carosati, D.
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Chai, Y.
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Kurtanidze, S. O.
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Kurtanidze, O. M.
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Nikolashvili, M. G.
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Chigladze, R. A.
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Ivanidze, R. Z.
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Kimeridze, G. N.
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Sigua, L. A.
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Joner, M. D.
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Spencer, M.
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Chilingarian, A.
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Rizzi, N.
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Cikota, S.
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Colak, S. M.
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Colombo, E.
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Contreras, J. L.
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Cortina, J.
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D'Amico, G.
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D'Elia, V.
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da Vela, P.
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de Angelis, A.
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de Lotto, B.
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Delfino, M.
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Delgado, J.
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Delgado Mendez, C.
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Depaoli, D.
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di Pierro, F.
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di Venere, L.
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Do Souto Espiñeira, E.
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Dominis Prester, D.
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Donini, A.
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Doro, M.
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Fallah Ramazani, V.
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Fattorini, A.
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Ferrara, G.
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Fonseca, M. V.
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Font, L.
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Fruck, C.
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Fukami, S.
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García López, R. J.
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Garczarczyk, M.
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Gasparyan, S.
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Gaug, M.
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Giglietto, N.
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Giordano, F.
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Gliwny, P.
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Godinović, N.
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Green, D.
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Hadasch, D.
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Hahn, A.
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Heckmann, L.
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Herrera, J.
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Hoang, J.
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Hrupec, D.
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Hütten, M.
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Inada, T.
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Inoue, S.
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Ishio, K.
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Iwamura, Y.
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Jiménez, I.
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Jormanainen, J.
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Jouvin, L.
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Kajiwara, Y.
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Karjalainen, M.
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Kerszberg, D.
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Kobayashi, Y.
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Kubo, H.
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Kushida, J.
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Lelas, D.
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Lindfors, E.
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Longo, F.
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López-Coto, R.
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López-Moya, M.
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López-Oramas, A.
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Loporchio, S.
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Machado de Oliveira Fraga, B.
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Maggio, C.
DOI
Abstract

Aims: We present a detailed characterisation and theoretical interpretation of the broadband emission of the paradigmatic TeV blazar Mrk 421, with a special focus on the multi-band flux correlations.
Methods: The dataset has been collected through an extensive multi-wavelength campaign organised between 2016 December and 2017 June. The instruments involved are MAGIC, FACT, Fermi-LAT, Swift, GASP-WEBT, OVRO, Medicina, and Metsähovi. Additionally, four deep exposures (several hours long) with simultaneous MAGIC and NuSTAR observations allowed a precise measurement of the falling segments of the two spectral components.
Results: The very-high-energy (VHE; E > 100 GeV) gamma rays and X-rays are positively correlated at zero time lag, but the strength and characteristics of the correlation change substantially across the various energy bands probed. The VHE versus X-ray fluxes follow different patterns, partly due to substantial changes in the Compton dominance for a few days without a simultaneous increase in the X-ray flux (i.e., orphan gamma-ray activity). Studying the broadband spectral energy distribution (SED) during the days including NuSTAR observations, we show that these changes can be explained within a one-zone leptonic model with a blob that increases its size over time. The peak frequency of the synchrotron bump varies by two orders of magnitude throughout the campaign. Our multi-band correlation study also hints at an anti-correlation between UV-optical and X-ray at a significance higher than 3σ. A VHE flare observed on MJD 57788 (2017 February 4) shows gamma-ray variability on multi-hour timescales, with a factor ten increase in the TeV flux but only a moderate increase in the keV flux. The related broadband SED is better described by a two-zone leptonic scenario rather than by a one-zone scenario. We find that the flare can be produced by the appearance of a compact second blob populated by high energetic electrons spanning a narrow range of Lorentz factors, from γ'min=2×104 to γ'max=6×105.

Light curves and spectral energy distributions data are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/655/A89

Volume
655
Start page
A89
Uri
Url
Issn Identifier
0004-6361
Ads BibCode
2021A&A...655A..89M
Rights
open.access
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