J/ApJ/858/68ivo://CDS.VizieR/J/ApJ/858/68doi:10.26093/cds/vizier.18580068CDSKapanadze B.Vercellone S.Romano P.Hughes P.Aller M.Aller H.,Kharshiladze O.Tabagari L.2025-11-03T20:13:33Z2019-05-06T08:22:31ZCDS support team

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

cds-question@unistra.frbl-lacertae-objectsultraviolet-photometryx-ray-sourcesWe present the results from a detailed spectral and timing study of Mrk 421 based on the rich archival Swift data obtained during 2009-2012. Best fits of the 0.3-10keV spectra were mostly obtained using the log-parabolic model showing the relatively low spectral curvature that is expected in the case of efficient stochastic acceleration of particles. The position of the synchrotron spectral energy density peak E_p_ of 173 spectra is found at energies higher than 2keV. The photon index at 1 keV exhibited a very broad range of values a=1.51-3.02, and very hard spectra with a<1.7 were observed during the strong X-ray flares, hinting at a possible hadronic jet component. The spectral parameters varied on diverse timescales and showed a correlation in some periods, which is expected in the case of first- and second-order Fermi acceleration. The 0.3-10keV flux showed strong X-ray flaring activity by a factor of 3-17 on timescales of a few days-weeks between the lowest historical state and that corresponding to a rate higher than 100ct/s. Moreover, 113 instances of intraday variability were revealed, exhibiting shortest flux-doubling/halving times of about 1.2hr, as well as brightenings by 7%-24% in 180-720 s and declines by 68%-22% in 180-900s. The X-ray and very high-energy fluxes generally showed a correlated variability, although one incidence of a more complicated variability was also detected, indicating that the multifrequency emission of Mrk 421 could not be generated in a single zone.2018ApJ...858...68Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/858/68CatalogResearchIsServedByTAP VizieR generic servicerelated-toVIII/76 : Leiden/Argentine/Bonn (LAB) Survey of Galactic HI (Kalberla+ 2005)J/ApJ/854/66 : Swift observations of Mrk 421. I. 2005-2008 (Kapanadze+, 2018)J/ApJ/848/103 : ~1.5yr Swift observations of Mrk 421 (Kapanadze+, 2017)J/ApJS/232/7 : 8yr R-band photopolarimetric data of Mrk 421 (Fraija+, 2017)J/ApJS/222/6 : 4.5yr obs. of Mrk421 with ARGO-YBJ + Fermi (Bartoli+, 2016)J/ApJ/831/102 : Swift and NuSTAR obs. of the BL Lac Mrk 421 (Kapanadze+, 2016)J/A+A/593/A91 : Mrk 421 multi-wavelength variability, 2007-2009 (Ahnen+, 2016)J/MNRAS/458/56 : TeV blazar X-ray spectral studies (Wierzcholska+, 2016)J/ApJS/218/23 : Fermi LAT third source catalog (3FGL) (Acero+, 2015)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/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/A+A/545/A117 : Monitoring of Mrk 421 at 15 and 24 GHz (Lico+, 2012)J/ApJS/194/29 : Observations of blazars at 15GHz (Richards+, 2011)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/858/68https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/858/68http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/858/68https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/858/68https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/858/68http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/858/68GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapX-rayUVdefaultJ/ApJ/858/68/table1Summary of the XRT and UVOT observations in 2009 January - 2012 DecemberobsIDObservation identifiermeta.id;obs.param;obsintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintstartUTC date of observation start, YYYY-MM-DDstime.start;obsnullableendUTC date of observation end, YYYY-MM-DDstime.end;obsnullableExp[35/4363] Exposure timestime.duration;obs.exposureintXRT[1.8/115]? Observation-binned 0.3-10keV count ratect/sphot.count;em.X-rayfloatnullablee_XRT[0.04/1.3]? Uncertainty in XRTct/sstat.errorfloatnullableuvw1mag[10.6/12.5]? De-reddened Swift/UVOT uvw1 band magnitudemagphot.mag;em.UVfloatnullablee_uvw1mag[0.02/0.06]? Uncertainty in uvw1magmagstat.error;phot.magfloatnullableFuvw1[9/47.4]? De-reddened Swift/UVOT uvw1 band flux densitymJyphot.flux;em.UVfloatnullablee_Fuvw1[0.07/1.5]? Uncertainty in Fuvw1mJystat.errorfloatnullableuvm2mag[11/13]? De-reddened Swift/UVOT uvm2 band magnitudemagphot.mag;em.UVfloatnullablee_uvm2mag[0.03/0.05]? Uncertainty in uvm2magmagstat.error;phot.magfloatnullableFuvm2[5/29.4]? De-reddened Swift/UVOT uvm2 band flux densitymJyphot.flux;em.UVfloatnullablee_Fuvm2[0.01/0.7]? Uncertainty in Fuvm2mJystat.errorfloatnullableuvw2mag[10.6/12.5]? De-reddened Swift/UVOT uvw2 band magnitudemagphot.mag;em.UVfloatnullablee_uvw2mag[0.03/0.06]? Uncertainty in uvw2magmagstat.error;phot.magfloatnullableFuvw2[6.2/40.2]? De-reddened Swift/UVOT uvw2 band flux densitymJyphot.flux;em.UVfloatnullablee_Fuvw2[0.1/1]? Uncertainty in Fuvw2mJystat.errorfloatnullableJDStart date converted to Julian Date by CDSdtime.epochcharAllDisplay all data for this ObsIDmeta.ref.urlcharJ/ApJ/858/68/table2Results of the spectral analysis with the log-parabolic modelAllDisplay all data for this ObsIDmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintobsIDObservation identifiermeta.id;obslongORSOrbit/Segment code for model fit (G1)meta.id;obschara[1.5/3.1] Model parameter, photon index at the energy E1meta.code;stat.param;meta.modelledfloate_a[0.01/0.1] Uncertainty in astat.errorfloatb[0.08/0.7] Model parameter, curvature parameterstat.param;meta.modelledfloate_b[0.03/0.2] Uncertainty in bstat.errorfloatEp[0.002/15.2] Model parameter, position of the SED peakkeVstat.param;meta.modelled;stat.maxfloate_Ep[0.001/1.6] Uncertainty in EpkeVstat.errorfloat10K[0.01/9.2] Model parameter, normalization factor, x10stat.paramfloate_10K[0.001/0.02] Uncertainty in Kstat.errorfloatchi2[0.8/2.3] Reduced {chi}^2 parameterstat.paramfloatDOF[14/332] Fit degrees of freedomstat.fit.dofintlogFS[-10.4/-8.6] Log unabsorbed 0.3-2 keV Fluxlog(mW.m**-2)phot.flux;em.X-ray.softfloate_logFS[0.003/0.02] Uncertainty in logFSlog(mW.m**-2)stat.errorfloatlogFH[-11.3/-8.5] Log unabsorbed 2-10 keV Fluxlog(mW.m**-2)phot.flux;em.X-ray.hardfloate_logFH[0.007/0.2] Uncertainty in logFHlog(mW.m**-2)stat.errorfloatlogFT[-10.4/-8.3] Log unabsorbed 0.3-10 keV Fluxlog(mW.m**-2)phot.flux;em.X-rayfloate_logFT[0.004/0.03] Uncertainty in logFHlog(mW.m**-2)stat.errorfloatHR[0.04/1.5] Hardness ratio (G2)phot.flux;arith.ratiofloate_HR[0.003/0.07] Uncertainty in HRstat.errorfloatJ/ApJ/858/68/table5The results of the XRT spectral analysis with a simple power-law modelrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintobsIDObservation identifiermeta.id;obsintORSOrbit/Segment code for model fit (G1)meta.id;obscharGamma[1.7/3] Photon index in PL modelmeta.code;spect.index;meta.modelledfloate_Gamma[0.01/0.05] Uncertainty in Gammastat.errorfloatK[0.01/0.6] Normalizationstat.fit.paramfloate_K[0.001/0.007] Uncertainty in Kstat.errorfloatchi2[0.8/1.2] Reduced {chi}^2^ parameterstat.paramfloatDOF[40/335] Fit degrees of freedomstat.fit.dofintlogFS[-10.4/-8.8] Log unabsorbed 0.3-2keV Fluxlog(mW.m**-2)phot.flux;em.X-ray.softfloate_logFS[0.004/0.02] Uncertainty in logFSlog(mW.m**-2)stat.errorfloatlogFH[-11.2/-8.7] Log unabsorbed 2-10keV Fluxlog(mW.m**-2)phot.flux;em.X-ray.hardfloate_logFH[0.006/0.04] Uncertainty in logFHlog(mW.m**-2)stat.errorfloatlogFT[-10.3/-8.4] Log unabsorbed 0.3-10keV Fluxlog(mW.m**-2)phot.flux;em.X-rayfloate_logFT[0.004/0.02] Uncertainty in logFHlog(mW.m**-2)stat.errorfloatHR[0.1/1.4] Hardness ratio (G2)phot.flux;arith.ratiofloate_HR[0.007/0.07] Uncertainty in HRstat.errorfloatAllDisplay all data for this ObsIDmeta.ref.urlcharJ/ApJ/858/68/table7Summary of the 0.3-10keV intraday-variabilities (IDVs) in 2009 February - 2012 AprilrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintobsIDObservation identifier (1)meta.id;obsintobsID2? Second observation identifier (1)meta.id;obsintnullableUTDate1UT Date of observation 1, YYYY-MM-DD (2)time.epoch;obsnullableUTDate2UT Date of observation 2, YYYY-MM-DD (2)time.epochnullableExp[0.07/24] Total length of the particular observation (2)htime.expofloatchi2[2.5/7858]? Reduced {chi}^2^ parameterstat.paramdoublenullableDOF[1/31]? Fit degrees of freedomstat.fit.dofintnullableORSOrbit segment (G1) (2)meta.id;obscharFvar[2/63.4]? Fractional variability amplitude%src.var.amplitudefloatnullablee_Fvar[0.2/2.7]? Uncertainty in Fvar%stat.errorfloatnullableParam-Min[1.5/2.9]? LP/PL model Param minimum (3)stat.param;meta.modelled;stat.minfloatnullablee_Param-Min[0.01/0.05]? Uncertainty in e_Param-Min (3)stat.errorfloatnullableParam-Max[1.6/3]? LP/PL model Param maximum (3)stat.param;meta.modelled;stat.maxfloatnullablee_Param-Max[0.01/0.05]? Uncertainty in e_Param-Max (3)stat.errorfloatnullableParam? Param designation (3)meta.notecharb-min[0.08/0.6]? Min curvature parameter in LP modelstat.param;meta.modelled;stat.minfloatnullablee_b-min[0.03/0.2]? Uncertainty in b-minstat.errorfloatnullableb-max[0.1/0.7]? Max curvature parameter in LP modelstat.param;meta.modelled;stat.maxfloatnullablee_b-max[0.03/0.2]? Uncertainty in b-maxstat.errorfloatnullableEp-min[0.002/7]? Minimum position of the SED peak in LP modelkeVpos;stat.max;stat.minfloatnullablee_Ep-min[0.001/0.7]? Uncertainty in Ep-minkeVstat.errorfloatnullableEp-max[0.03/15.2]? Max position of the SED peak in LP modelkeVstat.paramfloatnullablee_Ep-max[0.01/1.6]? Uncertainty in Ep-maxkeVstat.errorfloatnullableHR-min[0.1/1.4]? Minimum hardness ratiophot.flux;stat.minfloatnullablee_HR-min[0.004/0.04]? Uncertainty in HR-minstat.errorfloatnullableHR-max[0.1/1.5]? Maximum hardness ratiophot.flux;stat.maxfloatnullablee_HR-max[0.009/0.06]? Uncertainty in HR-maxstat.errorfloatnullableAllDisplay all data for this ObsIDmeta.ref.urlchar