Unravelling the complex behavior of Mrk 421 with simultaneous X-ray and VHE observations during an extreme flaring activity in April 2013

Tutkimustuotos: Lehtiartikkelivertaisarvioitu



  • University of Turku
  • Instituto de Astrofísica de Canarias
  • University of La Laguna
  • Università di Udine, and INFN Trieste
  • Japanese MAGIC Consortium
  • INAF National Institute for Astrophysics
  • ETH Zurich
  • Technische Universität Dortmund
  • Croatian MAGIC Consortium
  • Saha Institute of Nuclear Physics
  • Centro Brasileiro de Pesquisas Físicas
  • Universidad Complutense de Madrid
  • University of Łódź
  • Università di Siena, and INFN Pisa
  • Deutsches Elektronen-Synchrotron
  • Università di Padova and INFN
  • Istituto Nazionale di Fisica Nucleare
  • Max-Planck-Institut für Physik
  • Barcelona Institute of Science and Technology (BIST)
  • Università di Pisa
  • INFN Pisa
  • Universitat de Barcelona
  • International Center for Relativistic Astrophysics Network (ICRANet)
  • University of Würzburg
  • Finnish MAGIC Consortium
  • Universitat Autonoma de Barcelona
  • University of Trieste
  • Bulgarian Academy of Sciences
  • University of Bologna
  • INAF, Osservatorio Astronomico di Trieste
  • Princeton University
  • US Naval Research Laboratory
  • INAF Istituto di Radioastronomia
  • Harvard-Smithsonian Center for Astrophysics
  • Harvard University
  • Stanford University
  • Columbia University
  • Italian Space Agency
  • ASI Science Data Center
  • INAF, Osservatorio Astronomico di Roma
  • INAF, Osservatorio Astrofisico di Torino
  • Instituto de Astrofisica de Andalucia (Spain)
  • St. Petersburg State University
  • University of Crete
  • Foundation for Research and Technology—Hellas, IESL, Voutes
  • Abastumani Observatory
  • National Central University
  • Astronomical Observatory
  • Boston University
  • Kazan Federal University
  • Guangzhou University
  • Pulkovo Observatory
  • University of Arizona
  • Salt Lake Community College
  • Istanbul University
  • Brigham Young University
  • University of Colorado Denver
  • Purdue University
  • Universidad de Chile
  • California Institute of Technology


We report on a multi-band variability and correlation study of the TeV blazar Mrk 421 during an exceptional flaring activity observed from 2013 April 11 to 2013 April 19. The study uses, among others, data from GASP-WEBT, Swift, NuSTAR, Fermi-LAT, VERITAS, and MAGIC. The large blazar activity, and the 43 hours of simultaneous NuSTAR and MAGIC/VERITAS observations, permitted variability studies on 15 minute time bins, and over three X-ray bands (3-7 keV, 7-30 keV and 30-80 keV) and three very-high-energy (>0.1 TeV, hereafter VHE) gamma-ray bands (0.2-0.4 TeV, 0.4-0.8 TeV and >0.8 TeV). We detected substantial flux variations on multi-hour and sub-hour timescales in all the X-ray and VHE gamma-ray bands. The characteristics of the sub-hour flux variations are essentially energy-independent, while the multi-hour flux variations can have a strong dependence on the energy of the X-ray and the VHE gamma rays. The three VHE bands and the three X-ray bands are positively correlated with no time-lag, but the strength and the characteristics of the correlation changes substantially over time and across energy bands. Our findings favour multi-zone scenarios for explaining the achromatic/chromatic variability of the fast/slow components of the light curves, as well as the changes in the flux-flux correlation on day-long timescales. We interpret these results within a magnetic reconnection scenario, where the multi-hour flux variations are dominated by the combined emission from various plasmoids of different sizes and velocities, while the sub-hour flux variations are dominated by the emission from a single small plasmoid moving across the magnetic reconnection layer.


AlkuperäiskieliEi tiedossa
JulkaisuAstronomy & Astrophysics
TilaHyväksytty/In press - 1 tammikuuta 2020
OKM-julkaisutyyppiA1 Julkaistu artikkeli, soviteltu

ID: 40659661