Multiwavelength variability and correlation studies of Mrk 421 during historically low X-ray and γ-ray activity in 2015-2016
: Acciari VA, Ansoldi S, Antonelli LA, Asano K, Babic A, Banerjee B, 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, Bonnoli G, 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, Da Vela P, Dazzi F, De Angelis A, De Lotto B, Delfino M, Delgado J, Mendez CD, Depaoli D, Di Girolamo T, Di Pierro F, Di Venere L, Neira EDE, Prester DD, Donini A, Doro M, Ramazani VF, Fattorini A, Ferrara G, Foffano L, 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, 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 M, Lopez-Coto R, 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, Mender S, Micanovic S, Miceli D, Miener T, Minev M, Miranda JM, 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 JM, Pavletic L, Penil P, Perennes C, Persic M, Moroni PGP, Prandini E, Priyadarshi C, Puljak I, Rhode W, Ribo 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, Snidaric I, Sobczynska D, Spolon A, Stamerra A, Strom D, Strzys M, Suda Y, Suric T, Takahashi M, Tavecchio F, Temnikov P, Terzic T, Teshima M, Torres-Alba N, Tosti L, Truzzi S, van Scherpenberg J, Vanzo G, Acosta MV, Ventura S, Verguilov V, Vigorito CF, Vitale V, Vovk I, Will M, Zaric 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, Sliusar V, Theissen F, Walter R, Valverde J, Horan D, Giroletti M, Perri M, Verrecchia F, Leto C, Sadun AC, Moody JW, Joner M, Marscher AP, Jorstad SG, Lahteenmaki A, Tornikoski M, Ramakrishnan V, Jarvela E, Vera RJC, Righini S, Lien AY
Publisher: OXFORD UNIV PRESS
: 2021
: Monthly Notices of the Royal Astronomical Society
: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
: MON NOT R ASTRON SOC
: 504
: 1427
: 1451
: 25
: 0035-8711
: 1365-2966
DOI: https://doi.org/10.1093/mnras/staa3727
: https://research.utu.fi/converis/portal/detail/Publication/66401587
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 Metsahovi, 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 x 10(-12) ph cm(-2) s(-1)) and in the 2-10 keV (X-ray) band (F2-10 keV < 3.6 x 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) gamma-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(-6)(+9) 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.