Investigation of the correlation patterns and the Compton dominance variability of Mrk 421 in 2017
: Acciari VA, Ansoldi S, Antonelli LA, Engels AA, Artero M, Asano K, Baquero A, de Almeida UB, Barrio JA, Gonzalez JB, Bednarek W, Bellizzi L, Bernardini E, Bernardos M, Berti A, Besenrieder J, Bhattacharyya W, Bigongiari C, Blanch O, Bosnjak Z, Busetto G, Carosi R, Ceribella G, Cerruti M, Chai Y, Chilingarian A, Cikota S, Colak SM, Colombo E, Contreras JL, Cortina J, Covino S, D'Amico G, D'Elia V, DaVela P, Dazzi F, De Angelis A, De Lotto B, Delfino M, Delgado J, Mendez CD, Depaoli D, Di Pierro F, DiVenere L, Espineira ED, Prester DD, Donini A, Doro M, Ramazani VF, Fattorini A, Ferrara G, Fonseca MV, Font L, Fruck C, Fukami S, Lopez RJG, Garczarczyk M, Gasparyan S, Gaug M, Giglietto N, Giordano F, Gliwny P, Green JG, Green D, Hadasch D, Hahn A, Heckmann L, Herrera J, Hoang J, Hrupec D, Hutten M, Inada T, Inoue S, Ishio K, Iwamura Y, Jimenez 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, Lopez-Coto R, Lopez-Moya M, Lopez-Oramas A, Loporchio S, Fraga BMD, Maggio C, Majumdar P, Makariev M, Mallamaci M, Maneva G, Manganaro M, Maraschi L, Mariotti M, Martinez M, Mazin D, Menchiari S, Mender S, Miceli D, Miener T, Minev M, Miranda JM, 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 JM, Penil P, Perennes C, Persic M, Moroni PGP, Prandini E, Priyadarshi C, Puljak I, Ribo M, Rico J, Righi C, Rugliancich A, Saha L, Sahakyan N, Saito T, Sakurai S, Satalecka K, Saturni FG, Schmidt K, Schweizer T, Sitarek J, Snidaric I, Sobczynska D, Spolon A, Stamerra A, Strom D, Strzys M, Suda Y, Takahashi M, Tavecchio F, Temnikov P, Teshima M, Tosti L, Truzzi S, Tutone A, Ubach S, van Scherpenberg J, Vanzo G, Acosta MV, Ventura S, Verguilov V, Vigorito CF, Vitale V, Vovk I, Will M, Wunderlich C, Zaric D, 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 AY, Balokovic M, Madejski GM, Perri M, Verrecchia F, Leto C, Lahteenmaki A, Tornikoski M, Ramakrishnan V, Jarvela E, Vera RJC, Villata M, Raiteri CM, Gupta AC, 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 VM, Borman GA, Grishina TS, Hagen-Thorn VA, Kopatskaya EN, Larionova EG, Larionova LV, Morozova DA, Nikiforova AA, Savchenko SS, Troitskiy IS, Troitskaya YV, Vasilyev AA, Merkulova OA, Chen WP, Samal M, Lin HC, Moody JW, Sadun AC, Jorstad SG, Marscher AP, Weaver ZR, Feige M, Kania J, Kopp M, Kunkel L, Reinhart D, Scherbantin A, Schneider L, Lorey C, Acosta-Pulido JA, Carnerero MI, Carosati D, Kurtanidze SO, Kurtanidze OM, Nikolashvili MG, Chanishvili RG, Chigladze RA, Ivanidze RZ, Kimeridze GN, Sigua LA, Joner MD, Spencer M, Giroletti M, Marchili N, Righini S, Rizzi N, Bonnoli G
Publisher: EDP SCIENCES S A
: 2021
: Astronomy and Astrophysics
: ASTRON ASTROPHYS
: ARTN A89
: 655
: 36
: 0004-6361
: 1432-0746
DOI: https://doi.org/10.1051/0004-6361/202141004
: https://www.aanda.org/articles/aa/full_html/2021/11/aa41004-21/aa41004-21.html
: https://research.utu.fi/converis/portal/detail/Publication/68451837
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 Metsahovi. 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 3 sigma. 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 gamma(min)' = 2 x 10(4) to gamma(max)' = 6 x 10(5).
