J/ApJ/913/146ivo://CDS.VizieR/J/ApJ/913/146doi:10.26093/cds/vizier.19130146CDSMishra H.D.Dai X.Chen P.Cheng J.Jayasinghe T.Tucker M.A.,Vallely P.J.Bersier D.Bose S.Do A.Dong S.Holoien T.W.-S.,Huber M.E.Kochanek C.S.Liang E.Payne A.V.Prieto J.Shappee B.J.,Stanek K.Z.Bhatiani S.Cox J.DeFrancesco C.Shen Z.Thompson T.A.,Wang J.2023-01-18T06:13:13Z2022-12-28T12:01:23ZCDS support team

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

cds-question@unistra.fractive-galactic-nucleivisible-astronomybroad-band-photometrygamma-ray-astronomybl-lacertae-objectsquasarsspectroscopyBlazars are active galactic nuclei with their relativistic jets pointing toward the observer, comprising two major subclasses, flat-spectrum radio quasars (FSRQs) and BL Lac objects. We present multiwavelength photometric and spectroscopic monitoring observations of the blazar B2 1420+32, focusing on its outbursts in 2018-2020. Multiepoch spectra show that the blazar exhibited large-scale spectral variability in both its continuum and line emission, accompanied by dramatic gamma-ray and optical variability by factors of up to 40 and 15, respectively, on week to month timescales. Over the last decade, the gamma-ray and optical fluxes increased by factors of 1500 and 100, respectively. B2 1420+32 was an FSRQ with broad emission lines in 1995. Following a series of flares starting in 2018, it transitioned between BL Lac and FSRQ states multiple times, with the emergence of a strong Fe pseudocontinuum. Two spectra also contain components that can be modeled as single-temperature blackbodies of 12000 and 5200K. Such a collection of "changing-look" features has never been observed previously in a blazar. We measure gamma-ray-optical and interband optical lags implying emission-region separations of less than 800 and 130 gravitational radii, respectively. Since most emission-line flux variations, except the Fe continuum, are within a factor of 2-3, the transitions between FSRQ and BL Lac classifications are mainly caused by the continuum variability. The large Fe continuum flux increase suggests the occurrence of dust sublimation releasing more Fe ions in the central engine and an energy transfer from the relativistic jet to subrelativistic emission components.2021ApJ...913..146Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/913/146CatalogResearchIsServedByTAP VizieR generic servicerelated-toII/366 : ASAS-SN catalog of variable stars (Jayasinghe+, 2018-2020)J/A+A/375/739 : Hard X-ray properties of blazars (Donato+, 2001)J/ApJ/613/682 : AGN masses and broad-line region sizes (Peterson+, 2004)J/ApJ/696/870 : Catalina Real-time Transient Survey (CRTS) (Drake+, 2009)J/ApJ/698/895 : Variations in QSOs optical flux (Kelly+, 2009)J/A+A/495/691 : Multifreq. catalog of blazars, Roma-BZCAT (Massaro+, 2009)J/ApJS/194/45 : QSO properties from SDSS-DR7 (Shen+, 2011)J/ApJ/788/48 : X-ray through NIR photometry of NGC 2617 (Shappee+, 2014)J/MNRAS/454/3864 : Orientation & QSO BH mass estimation (Brotherton+ 2015)J/ApJ/804/7 : SaMOSA: opt. spectroscopy of 7 Fermi blazars (Isler+, 2015)J/A+A/594/A116 : HI4PI spectra and column density maps (HI4PI team+, 2016)J/ApJ/840/97 : Opt. reverberation mapping of 5 AGNs (Fausnaugh+, 2017)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/913/146https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/913/146http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/913/146https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/913/146https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/913/146http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/913/146GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapGamma-rayOpticaldefaultJ/ApJ/913/146/table1B2 1420+32 optical lightcurvesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJD[53479.27/58967.95] Modified Julian Date (JD-2400000.5)dtime.epochdoubleTelTelescope (1)meta.id;instr.telcharFiltFilter (g, B or V)meta.id;instr.filtercharomag[14.16/19] Observed magnitude in Filtmagphot.magfloate_omag[0/0.4] Uncertainty in omagmagstat.error;phot.magfloatJ/ApJ/913/146/table2B2 1420+32 Fermi LAT lightcurvesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJD[54772.66/59090.83] Modified Julian Date (JD-2400000.5)dtime.epochdoubleBinBinning sizetime.intervalcharFlux[0.03/201] 0.1-500GeV Flux,1e-08ph.s**-1.cm**-2phot.flux.density;em.gamma.hardfloate_Flux[0.0/58.1] Uncertainty in Flux1e-08ph.s**-1.cm**-2stat.error;phot.fluxfloatJ/ApJ/913/146/table3B2 1420+32 spectra continuum analysisMJD[53472/58677.4] Modified Julian Datedtime.epochdoublerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeq[1/9] Running sequence number of spectrummeta.numberintTelTelescopemeta.id;instr.telcharRes[2.5/7] Resolution in {AA}0.1nmspect.resolutionfloatAmp[2.3/160] Power-law amplitude normalized to 3000{AA} with units of 10^-16^erg/s/cm^2^/{AA}1e-18W.m**-2.nm**-1src.var.amplitudefloate_Amp[0.0042/1.4] Lower uncertainty on Amp1e-18W.m**-2.nm**-1stat.errorfloatE_Amp[0.0042/1.3] Upper uncertainty on Amp1e-18W.m**-2.nm**-1stat.error;stat.maxfloatIndex[0.45/1.9] Power-law index 1spect.indexfloate_Index[0.008/0.11] Lower uncertainty on Indexstat.error;spect.indexfloatE_Index[0.008/0.1] Upper uncertainty on Indexstat.error;stat.maxfloatInd2[2.78/2.78]? Power-law index 2spect.indexfloatnullablee_Ind2[0.04/0.04]? Lower uncertainty on Ind2stat.errorfloatnullableE_Ind2[0.04/0.04]? Upper uncertainty on Ind2stat.error;stat.maxfloatnullablebbT[5200/12000]? Blackbody temperatureKphys.temperatureintnullablee_bbT[29/380]? Lower uncertainty on bbTKstat.errorintnullableE_bbT[29/320]? Upper uncertainty on bbTKstat.error;stat.maxintnullablebbF[4.8/6.2]? Blackbody flux in units of 10^-12^erg/s/cm^2^/{AA}1e-14W.m**-2.nm**-1phot.flux;meta.modelledfloatnullablee_bbF[0.12/0.35]? Lower uncertainty on bbF1e-14W.m**-2.nm**-1stat.errorfloatnullableE_bbF[0.12/0.35]? Upper uncertainty on bbF1e-14W.m**-2.nm**-1stat.error;stat.maxfloatnullableFileName of the spectrum file in subdirectory "fig4"meta.id;meta.filecharSpInteractive spectrum plotmeta.ref.urlchar