J/A+A/700/L12ivo://CDS.VizieR/J/A+A/700/L12doi:10.26093/cds/vizier/bc-nw/wbcCDSKovalev Y.Y.Pushkarev A.B.Gomez J.L.Homan D.C.Lister M.L.,Livingston J.D.Pashchenko I.N.Plavin A.V.Savolainen T.Troitsky S.V.2026-08-03T06:56:50Z2025-08-12T07:23:02ZCDS support team

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

cds-question@unistra.fractive-galactic-nucleiradio-galaxiesradio-continuum-emissionvery-long-baseline-interferometryThe acceleration process of massive particles as well as the production of very high-energy (VHE) photons and neutrinos remains a fundamental challenge in astrophysics. We investigate the parsec-scale jet structure and magnetic field of the blazar PKS 1424+240, which was selected on the basis of strong VHE gamma-ray emission and is identified with one of the highest peaks in the IceCube 9-year neutrino sky. We analyzed 15GHz VLBA observations of this BL Lac object by stacking 42 polarization-sensitive images collected in 2009-2025 to enhance the signal and reveal the persistent parsec-scale structure. Our observations uncover a rare scenario. The object is viewed inside the jet cone, very close to the axis of its relativistic jet, with a viewing angle of <0.6deg. This effectively maximizes Doppler boosting to values ~30 and enhances the electromagnetic and neutrino emission in the direction of the observer. Based on polarimetric observations, we unambiguously detect a net toroidal component in the magnetic field of the jet. This indicates a current-carrying jet that flows almost directly toward our line of sight. Blazars with very small jet viewing angles offer a solution to the Doppler factor crisis, i.e., to the longstanding mismatch between Doppler factors inferred from the low apparent jet speed in very long-baseline interferometry and those derived from VHE observations. We show that relativistic beaming plays the critical role in the gamma-ray and neutrino emission of blazars. This has direct implications for models of their multimessenger emission.2025A&A...700L..12Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/700/L12CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJS/234/12 : MOJAVE XV. VLBA obs. of AGN jets 1996-2016 (Lister+, 2018)J/MNRAS/520/6053 : MOJAVE XX. Linear polarization in AGN (Pushkarev+, 2023)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/700/L12https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/700/L12http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/700/L12https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/700/L12https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/700/L12http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/700/L12GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/700/L12/list (List of fits images)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/700/L12/list?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/700/L12/list?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/700/L12/list?GETtext/xml+votable180.050000true216.7516323.800010.0055555555555555566/8915https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/700/L12?format=asciiRadiodefaultJ/A+A/700/L12/listList of fits imagesrecnoRecord 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 datetime.epoch;obscharFreqObserved frequencyGHzem.freqdoublesizeSize of FITS fileKibytephys.size;meta.fitsintFileNameName of FITS file, in subdirectory fitsmeta.id;meta.fitscharTitleTitle of the FITS filemeta.title;meta.fitschar