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

DOI: 
10.1051/0004-6361/202141004
Publication date: 
24/11/2021
Main author: 
MAGIC Collaboration
IAA authors: 
Agudo, I.;Casadio, C.
Authors: 
MAGIC Collaboration;Acciari, V. A.;Ansoldi, S.;Antonelli, L. A.;Arbet Engels, A.;Artero, M.;Asano, K.;Babić, A.;Baquero, A.;Barres de Almeida, U.;Barrio, J. A.;Batković, I.;Becerra González, J.;Bednarek, W.;Bellizzi, L.;Bernardini, E.;Bernardos, M.;Berti, A.;Besenrieder, J.;Bhattacharyya, W.;Bigongiari, C.;Blanch, O.;Bošnjak, Ž.;Busetto, G.;Carosi, R.;Ceribella, G.;Cerruti, M.;Chai, Y.;Chilingarian, A.;Cikota, S.;Colak, S. M.;Colombo, E.;Contreras, J. L.;Cortina, J.;Covino, S.;D'Amico, G.;D'Elia, V.;da Vela, P.;Dazzi, F.;de Angelis, A.;de Lotto, B.;Delfino, M.;Delgado, J.;Delgado Mendez, C.;Depaoli, D.;di Pierro, F.;di Venere, L.;Do Souto Espiñeira, E.;Dominis Prester, D.;Donini, A.;Doro, M.;Fallah Ramazani, V.;Fattorini, A.;Ferrara, G.;Fonseca, M. V.;Font, L.;Fruck, C.;Fukami, S.;García López, R. J.;Garczarczyk, M.;Gasparyan, S.;Gaug, M.;Giglietto, N.;Giordano, F.;Gliwny, P.;Godinović, N.;Green, J. G.;Green, D.;Hadasch, D.;Hahn, A.;Heckmann, L.;Herrera, J.;Hoang, J.;Hrupec, D.;Hütten, M.;Inada, T.;Inoue, S.;Ishio, K.;Iwamura, Y.;Jiménez, I.;Jormanainen, J.;Jouvin, L.;Kajiwara, Y.;Karjalainen, M.;Kerszberg, D.;Kobayashi, Y.;Kubo, H.;Kushida, J.;Lamastra, A.;Lelas, D.;Leone, F.;Lindfors, E.;Lombardi, S.;Longo, F.;López-Coto, R.;López-Moya, M.;López-Oramas, A.;Loporchio, S.;Machado de Oliveira Fraga, B.;Maggio, C.;Majumdar, P.;Makariev, M.;Mallamaci, M.;Maneva, G.;Manganaro, M.;Maraschi, L.;Mariotti, M.;Martínez, M.;Mazin, D.;Menchiari, S.;Mender, S.;Mićanović, S.;Miceli, D.;Miener, T.;Minev, M.;Miranda, J. M.;Mirzoyan, R.;Molina, E.;Moralejo, A.;Morcuende, D.;Moreno, V.;Moretti, E.;Neustroev, V.;Nigro, C.;Nilsson, K.;Nishijima, K.;Noda, K.;Nozaki, S.;Ohtani, Y.;Oka, T.;Otero-Santos, J.;Paiano, S.;Palatiello, M.;Paneque, D.;Paoletti, R.;Paredes, J. M.;Pavletić, L.;Peñil, P.;Perennes, C.;Persic, M.;Prada Moroni, P. G.;Prandini, E.;Priyadarshi, C.;Puljak, I.;Ribó, M.;Rico, J.;Righi, C.;Rugliancich, A.;Saha, L.;Sahakyan, N.;Saito, T.;Sakurai, S.;Satalecka, K.;Saturni, F. G.;Schmidt, K.;Schweizer, T.;Sitarek, J.;Šnidarić, I.;Sobczynska, D.;Spolon, A.;Stamerra, A.;Strom, D.;Strzys, M.;Suda, Y.;Surić, T.;Takahashi, M.;Tavecchio, F.;Temnikov, P.;Terzić, T.;Teshima, M.;Tosti, L.;Truzzi, S.;Tutone, A.;Ubach, S.;van Scherpenberg, J.;Vanzo, G.;Vazquez Acosta, M.;Ventura, S.;Verguilov, V.;Vigorito, C. F.;Vitale, V.;Vovk, I.;Will, M.;Wunderlich, C.;Zarić, D.;Fact Collaboration;Baack, D.;Balbo, M.;Biederbeck, N.;Biland, A.;Bretz, T.;Buss, J.;Dorner, D.;Eisenberger, L.;Elsaesser, D.;Hildebrand, D.;Iotov, R.;Mannheim, K.;Neise, D.;Noethe, M.;Paravac, A.;Rhode, W.;Schleicher, B.;Sliusar, V.;Walter, R.;D'Ammando, F.;Horan, D.;Lien, A. Y.;Baloković, M.;Madejski, G. M.;Perri, M.;Verrecchia, F.;Leto, C.;Lähteenmäki, A.;Tornikoski, M.;Ramakrishnan, V.;Järvelä, E.;Vera, R. J. C.;Chamani, W.;Villata, M.;Raiteri, C. M.;Gupta, A. C.;Pandey, A.;Fuentes, A.;Agudo, I.;Casadio, C.;Semkov, E.;Ibryamov, S.;Marchini, A.;Bachev, R.;Strigachev, A.;Ovcharov, E.;Bozhilov, V.;Valcheva, A.;Zaharieva, E.;Damljanovic, G.;Vince, O.;Larionov, V. M.;Borman, G. A.;Grishina, T. S.;Hagen-Thorn, V. A.;Kopatskaya, E. N.;Larionova, E. G.;Larionova, L. V.;Morozova, D. A.;Nikiforova, A. A.;Savchenko, S. S.;Troitskiy, I. S.;Troitskaya, Y. V.;Vasilyev, A. A.;Merkulova, O. A.;Chen, W. P.;Samal, M.;Lin, H. C.;Moody, J. W.;Sadun, A. C.;Jorstad, S. G.;Marscher, A. P.;Weaver, Z. R.;Feige, M.;Kania, J.;Kopp, M.;Kunkel, L.;Reinhart, D.;Scherbantin, A.;Schneider, L.;Lorey, C.;Acosta-Pulido, J. A.;Carnerero, M. I.;Carosati, D.;Kurtanidze, S. O.;Kurtanidze, O. M.;Nikolashvili, M. G.;Chigladze, R. A.;Ivanidze, R. Z.;Kimeridze, G. N.;Sigua, L. A.;Joner, M. D.;Spencer, M.;Giroletti, M.;Marchili, N.;Righini, S.;Rizzi, N.;Bonnoli, G.
Journal: 
Astronomy and Astrophysics
Publication type: 
Article
Volume: 
655
Pages: 
A89
Abstract: 
<BR /> 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. <BR /> 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. <BR /> Results: The very-high-energy (VHE; E &gt; 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'<SUB>min</SUB>=2×10<SUP>4</SUP> to γ'<SUB>max</SUB>=6×10<SUP>5</SUP>. <P />Light curves and spectral energy distributions data are only available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr/">cdsarc.u-strasbg.fr</A> (ftp://130.79.128.5) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/655/A89">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/655/A89</A>
Database: 
ADS
URL: 
https://ui.adsabs.harvard.edu/#abs/2021A&A...655A..89M/abstract
ADS Bibcode: 
2021A&A...655A..89M
Keywords: 
galaxies: active;BL Lacertae objects: individual: Mrk 421;radiation mechanisms: non-thermal;Astrophysics - High Energy Astrophysical Phenomena