Multiwavelength variability and correlation studies of Mrk 421 during historically low X-ray and γ-ray activity in 2015-2016

Acciari V. A.; Ansoldi S.; Antonelli L. A.; Asano K.; Babic A.; Banerjee B.; Baquero A.; Barres De Almeida U.; Barrio J. A.; Becerra Gonzalez J.; 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 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 Espineira 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.; Garcia Lopez R. J.; Garczarczyk M.; Gasparyan S.; Gaug M.; Giglietto N.; Giordano F.; Gliwny P.; Godinovic N.; Green J. G.; 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.; MacHado De Oliveira Fraga B.; 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 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.; Pavletic L.; Penil P.; Perennes C.; Persic M.; Prada Moroni P. G.; 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.; Vazquez Acosta M.; Ventura S.; Verguilov V.; Vigorito C. F.; 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.; 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.; Lahteenmaki A.; Tornikoski M.; Ramakrishnan V.; Jarvela E.; Vera R. J. C.; Righini S.; Lien A. Y.

Multiwavelength variability and correlation studies of Mrk 421 during historically low X-ray and γ-ray activity in 2015-2016

Acciari V. A.

•

Ansoldi S.

•

Antonelli L. A.

altro

Lien A. Y.

2021

journal article

Periodico

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

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, keV< 3.6× 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.