Multiwavelength variability and correlation studies of Mrk 421 during historically low X-ray and $\gamma$-ray activity in 2015$-$2016
Abstract
We report a characterization of the multi-band flux variability and correlations of the nearby (z=0.031) blazar Markarian 421 (Mrk 421) using data from Mets\"{a}hovi, Swift, Fermi-LAT, MAGIC, FACT and other collaborations and instruments from November 2014 till June 2016. Mrk 421 did not show any prominent flaring activity, but exhibited periods of historically low activity above 1 TeV (F 1.710 ph cm s) and in the 2-10 keV (X-ray) band (F3.610 erg cm s), during which the Swift-BAT data suggests an additional spectral component beyond the regular synchrotron emission. The highest flux variability occurs in X-rays and very-high-energy (E0.1 TeV) -rays, which, despite the low activity, show a significant positive correlation with no time lag. The HR and HR 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 days centered at time lag zero, and a positive correlation between the optical/GeV and the radio emission over a range of about 60 days centered at a time lag of days.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.
Keywords
Cite
@article{arxiv.2012.01348,
title = {Multiwavelength variability and correlation studies of Mrk 421 during historically low X-ray and $\gamma$-ray activity in 2015$-$2016},
author = {MAGIC Collaboration and V. A. Acciari and S. Ansoldi and L. A. Antonelli and K. Asano and A. Babić and B. Banerjee and A. Baquero and U. Barres de Almeida and J. A. Barrio and J. Becerra González and W. Bednarek and L. Bellizzi and E. Bernardini and M. Bernardos and A. Berti and J. Besenrieder and W. Bhattacharyya and C. Bigongiari and O. Blanch and G. Bonnoli and Ž. Bošnjak and G. Busetto and R. Carosi and G. Ceribella and M. Cerruti and Y. Chai and A. Chilingarian and S. Cikota and S. M. Colak and E. Colombo and J. L. Contreras and J. Cortina and S. Covino and G. D'Amico and V. D'Elia and P. Da Vela and F. Dazzi and A. De Angelis and B. De Lotto and M. Delfino and J. Delgado and C. Delgado Mendez and D. Depaoli and T. Di Girolamo and F. Di Pierro and L. Di Venere and E. Do Souto Espiñeira and D. Dominis Prester and A. Donini and M. Doro and V. Fallah Ramazani and A. Fattorini and G. Ferrara and L. Foffano and M. V. Fonseca and L. Font and C. Fruck and S. Fukami and R. J. García López and M. Garczarczyk and S. Gasparyan and M. Gaug and N. Giglietto and F. Giordano and P. Gliwny and N. Godinović and J. G. Green and D. Green and D. Hadasch and A. Hahn and L. Heckmann and J. Herrera and J. Hoang and D. Hrupec and M. Hütten and T. Inada and S. Inoue and K. Ishio and Y. Iwamura and J. Jormanainen and L. Jouvin and Y. Kajiwara and M. Karjalainen and D. Kerszberg and Y. Kobayashi and H. Kubo and J. Kushida and A. Lamastra and D. Lelas and F. Leone and E. Lindfors and S. Lombardi and F. Longo and M. López and R. López-Coto and A. López-Oramas and S. Loporchio and B. Machado de Oliveira Fraga and C. Maggio and P. Majumdar and M. Makariev and M. Mallamaci and G. Maneva and M. Manganaro and L. Maraschi and M. Mariotti and M. Martínez and D. Mazin and S. Mender and S. Mićanović and D. Miceli and T. Miener and M. Minev and J. M. Miranda and R. Mirzoyan and E. Molina and A. Moralejo and D. Morcuende and V. Moreno and E. Moretti and P. Munar-Adrover and V. Neustroev and C. Nigro and K. Nilsson and D. Ninci and K. Nishijima and K. Noda and S. Nozaki and Y. Ohtani and T. Oka and J. Otero-Santos and M. Palatiello and D. Paneque and R. Paoletti and J. M. Paredes and L. Pavletić and P. Peñil and C. Perennes and M. Persic and P. G. Prada Moroni and E. Prandini and C. Priyadarshi and I. Puljak and W. Rhode and M. Ribó and J. Rico and C. Righi and A. Rugliancich and L. Saha and N. Sahakyan and T. Saito and S. Sakurai and K. Satalecka and B. Schleicher and K. Schmidt and T. Schweizer and J. Sitarek and I. Šnidarić and D. Sobczynska and A. Spolon and A. Stamerra and D. Strom and M. Strzys and Y. Suda and T. Surić and M. Takahashi and F. Tavecchio and P. Temnikov and T. Terzić and M. Teshima and N. Torres-Albà and L. Tosti and S. Truzzi and J. van Scherpenberg and G. Vanzo and M. Vazquez Acosta and S. Ventura and V. Verguilov and C. F. Vigorito and V. Vitale and I. Vovk and M. Will and D. Zarić and FACT collaboration and : and A. Arbet-Engels and D. Baack and M. Balbo and M. Beck and N. Biederbeck and A. Biland and T. Bretz and K. Bruegge and J. Buss and D. Dorner and D. Elsaesser and D. Hildebrand and R. Iotov and M. Klinger and K. Mannheim and D. Neise and A. Neronov and M. Noethe and A. Paravac and W. Rhode and B. Schleicher and V. Sliusar and F. Theissen and R. Walter and MWL Collaborators and : and J. Valverde and D. Horan and M. Giroletti and M. Perri and F. Verrecchia and C. Leto and A. C. Sadun and J. W. Moody and M. Joner and A. P. Marscher and S. G. Jorstad and A. Lähteenmäki and M. Tornikoski and V. Ramakrishnan and E. Järvelä and R. J. C. Vera and S. Righini and A. Y. Lien},
journal= {arXiv preprint arXiv:2012.01348},
year = {2021}
}
Comments
45 pages, 30 figures, 6 tables, accepted for publication in MNRAS