J/A+A/704/A143ivo://CDS.VizieR/J/A+A/704/A143CDSRoesch F.Kadler M.Ros E.Ricci L.Gurwell M.A.Hovatta T.,MacDonald N.R.Readhead A.C.S.2026-03-02T06:25:50Z2025-12-05T09:25:44ZCDS support team

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

cds-question@unistra.frquasarsradio-sourcesgamma-ray-astronomyThe flat-spectrum radio quasar (FSRQ) 4C +01.28 is a bright and highly variable radio and gamma-ray emitter. We aim to pinpoint the location of the gamma-ray emitting region within its jet in order to derive strong constraints on gamma-ray emission models for blazar jets. We use radio and gamma-ray monitoring data obtained with the Atacama Large Millimeter/submillimeter Array (ALMA), the Owens Valley Radio Observatory (OVRO), the Submillimeter Array (SMA) and the Large Area Telescope on board the Fermi Gamma-ray Space Telescope (Fermi/LAT) to study the cross-correlation between gamma-ray and multi-frequency radio light curves. Moreover, we employ Very Long Baseline Array (VLBA) observations at 43GHz over a period of around nine years to study the parsec-scale jet kinematics of 4C +01.28. To pinpoint the location of the gamma-ray emitting region, we use a model in which outbursts shown in the gamma-ray and radio light curves are produced when moving jet components pass through the gamma-ray emitting and the radio core regions. We find two bright and compact newly ejected jet components that are likely associated with a high activity period visible in the Fermi/LAT gamma-ray and different radio light curves. The kinematic analysis of the VLBA observations leads to a maximum apparent jet speed of beta_app_=19+/-10 and an upper limit on the viewing angle of phi<4deg. Furthermore, we determine the power law indices that are characterizing the jet geometry, brightness temperature distribution and core shift to be l=0.974+/-0.098, s=-3.31+/-0.31 and kr=1.09+/-0.17, respectively, which are all in agreement with a conical jet in equipartition. A cross-correlation analysis shows that the radio light curves follow the gamma-ray light curve. We pinpoint the location of the gamma-ray emitting region with respect to the jet base to the range of 2.6pc<dgamma<20pc. Our derived observational limits places the location of gamma-ray production in 4C +01.28 beyond the expected extent of the broad-line region (BLR) and therefore challenges blazar-emission models that rely on inverse Compton up-scattering of seed photons from the BLR.2025A&A...704A.143Rhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/704/A143CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJS/260/12 : Jet kinematics of blazars at 43GHz with 10yrs obs.https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/704/A143https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/704/A143http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/704/A143https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/704/A143https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/704/A143http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/704/A143GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/704/A143/list (List of fits images (Figs. 1, B1 and B2))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/704/A143/list?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/704/A143/list?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/704/A143/list?GETtext/xml+votable180.050000true164.623361.566340.005555555555555556Associated datahttps://cdsarc.cds.unistra.fr/assocdata/?obs_collection=J/A+A/704/A1436/270602.8492099152324443e-23 2.8492099152324443e-23https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/704/A143?format=asciiGamma-rayRadiodefaultJ/A+A/704/A143/tablec2MODELFIT parameters of the fitted Gaussian jet componentsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDateUTC observation date'Y:M:D'time.epoch;obsnullableIDIdentification of the components (1)meta.id;meta.maincharoRARight ascension relative to the phase centermaspos.eq.ra;arith.difffloatoDEDeclination relative to the phase centermaspos.eq.dec;arith.difffloatl_MajAxisUpper limit flag on MajAxismeta.code.error;phys.angSizecharMajAxisFWHM of the major axis of the components (2)masphys.angSizefloatl_MinAxisUpper limit flag on MinAxismeta.code.error;phys.angSizecharMinAxisFWHM of the minor axis of the components (2)masphys.angSizefloatPA[] Position angle of the components (north through east)degpos.posAngfloatSFlux density of the components at 43GHz (3)Jyphot.flux.density;em.mm.30-50GHzfloatl_TbLower limit flag on Tbmeta.code.errorcharTbBrightness temperature of the components (4)Kphys.temperatureJ/A+A/704/A143/listList of fits images (Figs. 1, B1 and B2)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Right Ascension of center (J2000)degpos.eq.ra;meta.mainDEJ2000Declination of center (J2000)degpos.eq.dec;meta.mainNxNumber of pixels along X-axismeta.numberintNyNumber of pixels along Y-axismeta.numberintObs.dateObservation datestime.epoch;obsnullableFreqObserved frequencyHzem.freqdoublesizeSize of FITS fileKibytephys.size;meta.fitsintFileNameName of FITS file, in subdirectory fitsmeta.id;meta.fitscharTitleTitle of the FITS filemeta.title;meta.fitscharAssocDataAssociated Data web pagemeta.ref.urlchar