J/A+A/658/A5ivo://CDS.VizieR/J/A+A/658/A5doi:10.26093/cds/vizier.36580005CDSTimmerman R.Van Weeren R.J.Callingham J.R.Cotton W.D.Perley R.A.,Morabito L.K.Gizani N.A.B.Bridle A.H.O'Dea C.P.Baum S.A.,Tremblay G.R.Kharb P.Kassim N.E.Roettgering H.J.A.Botteon A.,Sweijen F.Tasse C.Brueggen M.Moldon J.Shimwell T.Brunetti G.2022-08-25T11:20:54Z2022-01-25T08:39:39ZCDS support team

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

cds-question@unistra.fractive-galactic-nucleiradio-galaxiesradio-continuum-emissionThe prominent radio source Hercules A features complex structures in its radio lobes. Despite being one of the most comprehensively studied sources in the radio sky, the origin of the ring structures in the Hercules A radio lobes remains an open question. We present the first sub-arcsecond angular resolution images at low frequencies (<300MHZ) of Hercules A, made with the International LOFAR Telescope. With the addition of data from the Karl G. Jansky Very Large Array, we map the structure of the lobes from 144MHz to 7GHz. We explore the origin of the rings within the lobes of Hercules A, and test whether their properties are best described by a shock model where shock waves are produced by the jet propagating in the radio lobe, or an inner-lobe model in which the rings are formed by decelerated jetted plasma. From spectral index mapping, our large frequency coverage reveals that the curvature of the different ring spectra increases with distance away from the central active galactic nucleus. We demonstrate that the spectral shape of the rings is consistent with synchrotron aging, which speaks in favor of an inner-lobe model, where the rings are formed from the deposition of material from past periods of intermittent core activity.2022A&A...658A...5Thttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/658/A5CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/658/A2 : LOFAR Long-Baseline Calibrator Survey. II. (Jackson+, 2022)J/A+A/658/A4 : LOFAR imaging of Arp299 at 150MHz (Ramirez-Olivencia, 2022)J/A+A/658/A6 : 3C293 high and low resolution maps (Kukreti+, 2022)J/A+A/658/A8 : Resolved jet of 3C 273 at 150 MHz (Harwood+, 2022)J/A+A/658/A10 : 3C295 LOFAR, MERLIN and VLA images (Bonnassieux+, 2022)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/658/A5https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/658/A5http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/658/A5https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/658/A5https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/658/A5http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/658/A5GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/658/A5/list (List of fits images)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/658/A5/list?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/658/A5/list?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/658/A5/list?GETtext/xml+votable180.050000true252.783954.992590.005555555555555556Associated datahttps://cdsarc.cds.unistra.fr/assocdata/?obs_collection=J/A+A/658/A56/31509https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/658/A5?format=asciiRadiodefaultJ/A+A/658/A5/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 datestime.epoch;obsnullableFreqObserved frequencyGHzem.freqfloatsizeSize 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