Multiwavelength variability and correlation studies of Mrk 421 during historically low X-ray and γ-ray activity in 2015–2016. Issue 1 (8th December 2020)

• Record Type: Journal Article
• Authors: Acciari, V A; Ansoldi, S; Antonelli, L A; Asano, K; Babić, A; Banerjee, B; Baquero, A; de Almeida, U Barres; Barrio, J A; Becerra González, J; Bednarek, W; Bellizzi, L; Bernardini, E; Bernardos, M; Berti, A; Besenrieder, J; Bhattacharyya, W; Bigongiari, C; Blanch, O; Bonnoli, G; 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 Girolamo, T; Di Pierro, F; Di Venere, L; Do Souto Espiñeira, E; Dominis Prester, D; Donini, A; Doro, M; Fallah Ramazani, V; Fattorini, A; Ferrara, G; Foffano, L; 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; 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, M; López-Coto, R; 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; 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; Munar-Adrover, P; Neustroev, V; Nigro, C; Nilsson, K; Ninci, D; Nishijima, K; Noda, K; Nozaki, S; Ohtani, Y; Oka, T; Otero-Santos, J; 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; Rhode, W; Ribó, M; Rico, J; Righi, C; Rugliancich, A; Saha, L; Sahakyan, N; Saito, T; Sakurai, S; Satalecka, K; Schleicher, B; 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; Torres-Albà, N; Tosti, L; Truzzi, S; van Scherpenberg, J; Vanzo, G; Vazquez Acosta, M; Ventura, S; Verguilov, V; Vigorito, C F; Vitale, V; Vovk, I; Will, M; Zarić, D; Arbet-Engels, A; Baack, D; Balbo, M; Beck, M; Biederbeck, N; Biland, A; Bretz, T; Bruegge, K; Buss, J; Dorner, D; Elsaesser, D; Hildebrand, D; Iotov, R; Klinger, M; Mannheim, K; Neise, D; Neronov, A; Noethe, M; Paravac, A; Rhode, W; Schleicher, B; Sliusar, V; Theissen, F; Walter, R; Valverde, J; Horan, D; Giroletti, M; Perri, M; Verrecchia, F; Leto, C; Sadun, A C; Moody, J W; Joner, M; Marscher, A P; Jorstad, S G; Lähteenmäki, A; Tornikoski, M; Ramakrishnan, V; Järvelä, E; Vera, R J C; Righini, S; Lien, A Y;
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 504:Issue 1(2021)
• Page Start: 1427
• Page End: 1451
• Publication Date: 2020-12-08
• Subjects: radiation mechanisms: non-thermal -- methods: data analysis -- methods: observational -- galaxies: active -- BL Lacertae objects: individual: Mrk 421; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/staa3727
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We report a characterization of the multiband flux variability and correlations of the nearby ( z = 0.031) blazar Markarian 421 (Mrk 421) using data from Metsähovi, Swift, Fermi -LAT, MAGIC, FACT, and other collaborations and instruments from 2014 November till 2016 June. Mrk 421 did not show any prominent flaring activity, but exhibited periods of historically low activity above 1 TeV ( F >1 TeV < 1.7 × 10 −12 ph cm −2 s −1 ) and in the 2–10 keV (X-ray) band ( F $_{2-10\, \mathrm{keV}}\lt 3.6\times 10^{-11}$ erg cm −2 s −1 ), during which the Swift -BAT data suggest an additional spectral component beyond the regular synchrotron emission. The highest flux variability occurs in X-rays and very high-energy ( E > 0.1 TeV) γ-rays, which, despite the low activity, show a significant positive correlation with no time lag. The HRkeV and HRTeV show the harder-when-brighter trend observed in many blazars, but the trend flattens at the highest fluxes, which suggests a change in the processes dominating the blazar variability. Enlarging our data set with data from years 2007 to 2014, we measured a positive correlation between the optical and the GeV emission over a range of about 60 d centred at time lag zero, and a positive correlation between the optical/GeV and the radio emission over a range of about 60 d centred at a time lag of $43^{+9}_{-6}$ d. This observation is consistent with the radio-bright zone being located about 0.2 parsec downstream from the optical/GeV emission regions of the jet. The flux distributions are better described with a lognormal function in most of the energy bands probed, indicating that the variability in Mrk 421 is likely produced by a multiplicative process.