J/ApJS/222/6ivo://CDS.VizieR/J/ApJS/222/6doi:10.26093/cds/vizier.22220006CDSBartoli B.Bernardini P.Bi X.J.Cao Z.Catalanotti S.Chen S.Z.,Chen T.L.Cui S.W.Dai B.Z.D'Amone A.DanzengluobuDe Mitri I.,D'Ettorre Piazzoli B.Di Girolamo T.Di Sciascio G.Feng C.F.Feng Z.,Feng Z.Gou Q.B.Guo Y.Q.He H.H.Hu H.Hu H.Iacovacci M.Iuppa R.,Jia H.Y.LabacirenLi H.J.Liu C.Liu J.Liu M.Y.Lu H.Ma L.L.,Ma X.H.Mancarella G.Mari S.M.Marsella G.Mastroianni S.Montini P.,Ning C.C.Perrone L.Pistilli P.Salvini P.Santonico R.Shen P.R.,Sheng X.D.Shi F.Surdo A.Tan Y.H.Vallania P.Vernetto S.,Vigorito C.Wang H.Wu C.Y.Wu H.R.Xue L.Yang Q.Y.Yang X.C.,Yao Z.G.Yuan A.F.Zha M.Zhang H.M.Zhang L.Zhang X.Y.Zhang Y.,Zhao J.ZhaxicirenZhaxisangzhuZhou X.X.Zhu F.R.Zhu Q.Q.,(the ARGO-YBJ Collaboration)2017-06-22T14:28:43Z2016-02-16T13:49:08ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frbl-lacertae-objectsgamma-ray-astronomyradio-sourcesx-ray-sourcesultraviolet-astronomyWe report on the extensive multi-wavelength observations of the blazar Markarian 421 (Mrk 421) covering radio to {gamma}-rays, during the 4.5yr period of ARGO-YBJ and Fermi common operation time, from 2008 August to 2013 February. These long-term observations, extending over an energy range of 18 orders of magnitude, provide a unique chance to study the variable emission of Mrk 421. In particular, due to the ARGO-YBJ and Fermi data, the entire energy range from 100MeV to 10TeV is covered without any gap. In the observation period, Mrk 421 showed both low- and high-activity states at all wavebands. The correlations among flux variations in different wavebands were analyzed. The X-ray flux is clearly correlated with the TeV {gamma}-ray flux, while the GeV {gamma}-rays only show a partial correlation with the TeV {gamma}-rays. Radio and UV fluxes seem to be weakly or not correlated with the X-ray and {gamma}-ray fluxes. Seven large flares, including five X-ray flares and two GeV {gamma}-ray flares with variable durations (3-58d), and one X-ray outburst phase were identified and used to investigate the variation of the spectral energy distribution with respect to a relative quiescent phase. During the outburst phase and the seven flaring episodes, the peak energy in X-rays is observed to increase from sub-keV to a few keV. The TeV {gamma}-ray flux increases up to 0.9-7.2 times the flux of the Crab Nebula. The behavior of GeV {gamma}-rays is found to vary depending on the flare, a feature that leads us to classify flares into three groups according to the GeV flux variation. Finally, the one-zone synchrotron self-Compton model was adopted to describe the emission spectra. Two out of three groups can be satisfactorily described using injected electrons with a power-law spectral index around 2.2, as expected from relativistic diffuse shock acceleration, whereas the remaining group requires a harder injected spectrum. The underlying physical mechanisms responsible for different groups may be related to the acceleration process or to the environment properties.2016ApJS..222....6Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/222/6CatalogResearchIsServedByTAP VizieR generic servicerelated-toVIII/76 : Leiden/Argentine/Bonn (LAB) Survey of Galactic HI (Kalberla+ 2005)J/A+A/578/A22 : Mrk421 in March 2010 (Aleksic+, 2015)J/A+A/576/A126 : The 2009 multiwavelength campaign on Mrk421 (Aleksic+, 2015)J/AJ/149/32 : Integrated radio continuum spectra of galaxies (Marvil+, 2015)J/A+A/562/A64 : Fermi detection of BL Lac objects (Wu+, 2014)J/ApJS/212/15 : Polarized NVSS sources SEDs (Farnes+, 2014)J/AJ/147/143 : MOJAVE. XI. Spectral distributions (Hovatta+, 2014)J/other/RAA/14.1135 : Doppler factor for a Fermi blazar sample (Fan+, 2014)J/ApJS/207/16 : BL Lac candidates for TeV observations (Massaro+, 2013)J/A+A/559/A75 : 43GHz observation of the blazar Mrk 421 (Blasi+, 2013)J/ApJS/209/14 : The Swift/BAT hard X-ray transient monitor (Krimm+, 2013)J/ApJS/199/31 : Fermi LAT second source catalog (2FGL) (Nolan+, 2012)J/ApJS/199/8 : Interstellar column densities compilation (Gudennavar+, 2012)J/A+A/545/A117 : Monitoring of Mrk 421 at 15 and 24 GHz (Lico+, 2012)J/A+A/541/A160 : Planck + X/{gamma} observations of blazars (Giommi+, 2012)J/ApJ/761/125 : X and {gamma} spectral indexes of Fermi blazars (Fan+, 2012)J/ApJ/754/23 : Blazar submm to {gamma}-ray luminosities (Leon-Tavares+, 2012)J/ApJ/744/177 : VLBA 5GHz observations of Fermi/LAT AGNs (Linford+, 2012)J/ApJ/741/30 : Radio/{gamma}-ray correlation in AGN (Ackermann+, 2011)J/ApJS/194/29 : Observations of blazars at 15GHz (Richards+, 2011)J/ApJS/186/378 : Hard X-ray survey from Swift-BAT 2004-2006 (Tueller+, 2010)J/ApJ/722/520 : Gamma-ray light curves of Fermi blazars (Abdo+, 2010)J/ApJ/716/30 : SED of Fermi bright blazars (Abdo+, 2010)J/AJ/137/5022 : Variability of radio-bright BL Lac objects (Nieppola+, 2009)J/ApJ/673/96 : BAT X-ray Survey - III (Ajello+, 2008)J/AJ/133/1947 : 37GHz observations of BL Lac objects (Nieppola+, 2007)J/other/APh/26.282 : AGN neutrino source candidates (Achterberg+, 2006)J/A+A/410/813 : 2001 Flare of Mkn 421 in gamma-ray (Aharonian+ 2003)J/A+A/390/39 : HEGRA AIROBICC gamma radiation above 15 TeV (Aharonian+, 2002)J/ApJS/140/143 : HST FOS spectral atlas (Bechtold+, 2002)J/A+AS/109/267 : Radio to X-Ray distribution of BL Lac Objects (Giommi+, 1995)http://tevcat.uchicago.edu/ : TeVCat online cataloghttp://fermi.gsfc.nasa.gov/ssc : The Fermi Science Support Centerhttp://swift.gsfc.nasa.gov/ : Swift home pagehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJS/222/6https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJS/222/6http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJS/222/6https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJS/222/6https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJS/222/6http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJS/222/6GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapGamma-rayRadioX-rayUVdefaultJ/ApJS/222/6/table1Light curves shown in Figure 2recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJD[54686.5/56329.5] Modified Julian Date; JD-2400000.5dtime.epochdoubleDt[0/15] Delta Timedpos.eq.decdoubleFluxFlux in detector units (1)phot.flux.densitydoubleDFluxDelta Flux in detector units (1)stat.errordoublex_FluxUnits for Flux, DFlux (1)meta.unit;phot.fluxcharDetDetector used (1)instr.setup;instr.detcharJ/ApJS/222/6/table5Energy and flux of the spectral points shown in Figure 7 and Figure 8recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStateActivity State for Mrk 421 (1)meta.idcharE[0/5.5] Photon energyTeVem.energydoubleFluxFlux, E^2^*dN/dE, erg/cm2/smW.m**-2phot.flux.densitydoubleDFluxDelta Flux, {delta}E^2^*dN/dE, erg/cm2/smW.m**-2stat.errordouble95ul95% Flux upper limit, erg/cm2/smW.m**-2phot.flux.densitydoubleDetDetector used (same detectors as in table 1)instr.setup;instr.detchar