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 Metsähovi, 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${}_{>1\mathrm{TeV}}<$ 1.7$\times$10${}^{-12}$ ph cm${}^{-2}$ s${}^{-1}$) and in the 2-10 keV (X-ray) band (F${}_{2-10\mathrm{keV}}<$3.6$\times$10${}^{-11}$ erg cm${}^{-2}$ s${}^{-1}$), 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 (E$>$0.1 TeV) $\gamma$-rays, which, despite the low activity, show a significant positive correlation with no time lag. The HR${}_{\mathrm{keV}}$ and HR${}_{\mathrm{TeV}}$ 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 $43_{-6}^{+9}$ 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.

arXiv comment45 pages, 30 figures, 6 tables, accepted for publication in MNRAS

References in corpus (65)

• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• The Large Area Telescope on the Fermi Gamma-ray Space Telescope Mission
• The Leiden/Argentine/Bonn (LAB) Survey of Galactic HI: Final data release of the combined LDS and IAR surveys with improved stray-radiation corrections
• Correcting for the Effects of Interstellar Extinction
• The Swift X-ray Telescope
• The Swift Ultra-Violet/Optical Telescope
• Central Masses and Broad-Line Region Sizes of Active Galactic Nuclei. II. A Homogeneous Analysis of a Large Reverberation-Mapping Database
• Fermi Large Area Telescope Fourth Source Catalog
• On characterising the variability properties of X-ray light curves from active galaxies
• Active Galactic Nuclei as scaled-up Galactic black holes
• On Uncertainties in Cross-Correlation Lags and the Reality of Wavelength-Dependent Continuum Lags in Active Galactic Nuclei
• The Swift/BAT Hard X-ray Transient Monitor
• BL Lac Objects in the Synchrotron Proton Blazar Model
• Blazars in the Fermi Era: The OVRO 40-m Telescope Monitoring Program
• The major upgrade of the MAGIC telescopes, Part II: A performance study using observations of the Crab Nebula
• Non-linear X-ray variability in X-ray binaries and active galaxies
• Multi-Epoch VLBA Observations of EGRET-Detected Quasars and BL Lac Objects: Superluminal Motion of Gamma-Ray Bright Blazars
• Kinematics of Parsec-Scale Jets of Gamma-Ray Blazars at 43~GHz within the VLBA-BU-BLAZAR Program
• Fermi-LAT Observations of Markarian 421: the Missing Piece of its Spectral Energy Distribution
• The flux-dependent amplitude of broadband noise variability in X-ray binaries and active galaxies
• The blazar TXS 0506+056 associated with a high-energy neutrino: insights into extragalactic jets and cosmic ray acceleration
• Design and Operation of FACT -- The First G-APD Cherenkov Telescope
• Multiwavelength Observations of Markarian 421 in March 2001: an Unprecedented View on the X-ray/TeV Correlated Variability
• Multiwaveband Polarimetric Observations of 15 Active Galactic Nuclei at High Frequencies: Correlated Polarization Behavior
• An Updated Ultraviolet Calibration for the Swift/UVOT
• Observations of Mkn 421 with the MAGIC Telescope
• Time-correlation between the radio and gamma-ray activity in blazars and the production site of the gamma-ray emission
• TeV and Multi-wavelength Observations of Mrk 421 in 2006-2008
• The radio/gamma-ray connection in Active Galactic Nuclei in the era of the Fermi Large Area Telescope
• Host galaxy subtraction of TeV candidate BL Lacertae objects
• Multiwavelength Study of Quiescent States of Mrk 421 with Unprecedented Hard X-Ray Coverage Provided by NuSTAR in 2013
• The Jets of TeV Blazars at Higher Resolution: 43 GHz and Polarimetric VLBA Observations from 2005-2009
• Unprecedented study of the broadband emission of Mrk 421 during flaring activity in March 2010
• The 2009 multiwavelength campaign on Mrk 421: Variability and correlation studies
• Measurement of the Crab Nebula spectrum over three decades in energy with the MAGIC telescopes
• The June 2008 flare of Markarian 421 from optical to TeV energies
• Variability in Blazars: Clues from PKS 2155-304
• Superorbital variability of X-ray and radio emission of Cyg X-1 - II. Dependence of the orbital modulation and spectral hardness on the superorbital phase
• A cut-off in the TeV gamma-ray spectrum of the SNR Cassiopeia A
• Efficient Nonthermal Particle Acceleration by the Kink Instability in Relativistic Jets
• Observation of Markarian 421 in TeV gamma rays over a 14-year time span
• 4.5 years multi-wavelength observations of Mrk 421 during the ARGO-YBJ and Fermi common operation time
• Locating the gamma-ray emission site in Fermi/LAT blazars from correlation analysis between 37 GHz radio and gamma-ray light curves
• Daily monitoring of TeV gamma-ray emission from Mrk 421, Mrk 501, and the Crab Nebula with HAWC
• Kink Instabilities In Relativistic Jets Can Drive Quasi-Periodic Radiation Signatures
• A combined radio and GeV gamma-ray view of the 2012 and 2013 flares of Mrk 421
• Time-dependent neutrino emission from Mrk 421 during flares and predictions for IceCube
• The Calibration of the Swift/UVOT Optical Observations: A Recipe for Photometry
• Dissecting the long-term emission behaviour of the BL Lac object Mrk 421
• Long-term lightcurves from combined unified very high energy $\gamma$-ray data
• The Great Markarian 421 Flare of February 2010: Multiwavelength variability and correlation studies
• The Halo Occupation Distribution of Active Galactic Nuclei
• X-Ray Variability of AGN and Relationship to Galactic Black Hole Binary Systems
• A decade of multi-wavelength observations of the TeV blazar 1ES 1215+303: Extreme shift of the synchrotron peak frequency and long-term optical-gamma-ray flux increase
• Polarization Signatures of Kink Instabilities in the Blazar Emission Region from Relativistic Magnetohydrodynamic Simulations
• Time series analysis of gamma-ray blazars and implications for the central black-hole mass
• On the origin of the hard X-Ray excess of high-synchrotron-peaked BL Lac object Mrk 421
• Very Long Baseline polarimetry and the gamma-ray connection in Markarian 421 during the broadband campaign in 2011
• Bimodal radio variability in OVRO-40m-monitored blazars
• Systematic Physical Characterization of the Gamma-Ray Spectra of 2FHL Blazars
• Flux Distribution of Gamma-Ray Emission in Blazars: The Example of Mrk 501
• Particle Acceleration And Emission Processes In Mrk 421
• Simultaneous observations of the blazar PKS2155-304 from Ultra-Violet to TeV energies
• Zenith angle dependence of the cosmic ray rate as measured with Imaging air-Cherenkov Telescopes
• A flat-spectrum flare in S4 0444+63 revealed by a new implementation of multi-wavelength single-dish observations

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• On the narrow spectral feature at $\sim$3 TeV in the MAGIC spectrum of Mrk 501
• Two-injection scenario for the hard X-ray excess observed in Mrk 421
• Imprint of "Local Opacity" Effect in Gamma-Ray Spectrum of Blazar Jet
• Time-Dependent Modeling of the Sub-Hour Spectral Evolution During the 2013 Outburst of Mrk 421
• VHE $\gamma$-ray observations of bright BL Lacs with the Large-Sized Telescope prototype (LST-1) of the CTAO
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• Characterizing Long-term Optical Variability Properties of $\gamma$-ray Bright Blazars
• Relentless multi-wavelength variability of Mrk 421 and Mrk 501
• Shortterm optical variability of 4C 29.45
• The Major Gamma-ray Imaging Cherenkov Telescopes (MAGIC)