J/A+A/705/A85ivo://CDS.VizieR/J/A+A/705/A85CDSZeng A.-L.Zhao W.Yang J.Hu X.-Z.Deng F.Lei Y.Hong X.Liu X.,Chen L.Liao M.Yang X.Shang H.-T.2026-03-02T06:25:50Z2026-01-09T10:14:05ZCDS support team

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

cds-question@unistra.fractive-galactic-nucleimagnetic-fieldspolarimetryradio-continuum-emissionradio-sourcesvery-long-baseline-interferometryIntermittent jet activity of Active Galactic Nuclei (AGNs) is a common phenomenon, whereas significant jet reorientation during episodic jet activity in relatively young radio galaxies are rarely reported. The quasar 0954+556 at z=0.903 is an intriguing source exhibiting an unusual radio jet structure with significantly different jet directions at kiloparsec (kpc) scales and at parsec (pc) scales. At kpc scales, images from Very Large Array (VLA) exhibit a bright core, a linear jet extending ~24kpc to the northwest, and a discrete jet component ~16kpc to the northeast. At pc scales, images from Very Long Baseline Array (VLBA) show a two-component structure with a projected separation of ~360pc in north-south direction. The peculiar structure of 0954+556 might result from jet reorientation. Here, we aim to investigate the possible mechanism via multiscale and multifrequency deep radio images. We performed VLA and VLBA observations of 0954+556. Together with some existing data in the NRAO data archive, we made multiple VLA images at 1.4-22 GHz and VLBA images at 1.7-43 GHz for various image analysis of the jet structure. We have identified the location of the radio core at pc scales, detected the faint counter jets at both pc and kpc scales for the first time, and revealed a diffuse emission region connecting pc and kpc-scale forward jets. Our spectral index distribution and spectral aging analysis indicate that 0954+556 might undergo at least two episodes of jet activity during the current AGN phase. Moreover, pc-scale polarization maps display a well-resolved spine-sheath polarization structure. It seems that the jet direction of 0954+556 changed significantly during intermittent jet activity. This may imply the different jet orientations and spectral ages observed from kpc to pc scales. The research provides a strong case that AGN jet direction might change rapidly on timescale of million years.2026A&A...705A..85Zhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/705/A85CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/705/A85https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/705/A85http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/705/A85https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/705/A85https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/705/A85http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/705/A85GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/705/A85/list (List of images and calibrated data)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/705/A85/list?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/705/A85/list?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/705/A85/list?GETtext/xml+votable180.050000true149.40910416755.3827133330.0055555555555555566/7426https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/705/A85?format=asciiRadiodefaultJ/A+A/705/A85/listList of images and calibrated datarecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.mainObs.dateObservation date (YYYY-MM-DD) (1)'Y:M:D'time.epoch;obsnullableArrayTelescope/array (VLA or VLBA)meta.id;instrcharFileNameFile name (image or calibrated visibilities) in subdirectory fits (2)meta.id;meta.fitscharTitleShort description of the file contentsmeta.notechar