J/A+A/704/A284ivo://CDS.VizieR/J/A+A/704/A284CDSWolnik K.Jamrozy M.2026-03-02T06:25:50Z2025-12-16T11:40:23ZCDS support team

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

cds-question@unistra.frradio-galaxiesinterferometryradio-continuum-emissionThe general population of radio galaxies, there exist several classes of peculiar objects. Among them, there are giant radio galaxies (GRGs with linear sizes greater than 0.7Mpc and double-double radio galaxies (DDRGs) showing signs of recurrent jet-formation activity. Observations and models developed in recent decades suggest that recurrent activity, among other factors, may stimulate the growth of the GRGs. However, the connection between the two classes of objects is still poorly understood and few of the known giant DDRGs were thoroughly studied. Our goal is to perform a detailed study of selected giant DDRGs - J1021+1216, J1528+0544, and J2345-0449. The collection of radio maps along with the basic parameters of the sources, such as independent measurements of flux density in the inner and outer lobes, measurements of linear sizes and axial ratio of the lobes, will facilitate further in-depth modeling of the objects performed in the second part of our study. In this study, we perform multifrequency radio observations of the selected sources with Karl G. Jansky Very Large Array and the upgraded Giant Metrewave Radio Telescope. Analysis of the radio-lobe morphology and the structure of the spectral index maps provides preliminary information about the sources' environment and activity. Outer doubles with asymmetric backflows and minor misalignments were observed in J1021+1216, J1528+0544, and J2345-0449. In J2345-0449, there appear low surface brightness wings close to the core. In all three sources, the shorter lobe is the brighter one, suggesting the existence of large scale inhomogeneties in the ambient medium. A trace of emission with low values of spectral index appears in the J1528+0544 outer double maps, possibly marking the orientation of the jet in the initial phase of activity. Asymmetries of the inner lobes in J1021+1216 and J2345-0449 can be explained by relativistic Doppler effect, while the J1528+0544 inner double structure requires a contamination of the radio cocoon. The shown examples of asymmetric backflows and wings in the outer doubles of the studied sources show the existence of inhomogeneities of the external medium around the host galaxies on the scale of the radio-lobe size, suggesting a complex evolution of the radio cocoons. The initial jets seem to clear the ambient medium for the subsequent phases of activity. Spectral aging analysis and dynamical modeling, made in the second part of this study, are necessary to confirm the results.2025A&A...704A.284Whttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/704/A284CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/704/A284https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/704/A284http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/704/A284https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/704/A284https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/704/A284http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/704/A284GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/704/A284/list (List of fits images)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/704/A284/list?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/704/A284/list?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/704/A284/list?GETtext/xml+votable180.050000true155.3524612.279380.0055555555555555566/17385 27594 31467https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/704/A284?format=asciiRadiodefaultJ/A+A/704/A284/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 frequencyHzem.freqdoublesizeSize of FITS fileKibytephys.size;meta.fitsintFileNameName of FITS file, in subdirectory fitsmeta.id;meta.fitscharTitleTitle of the FITS filemeta.title;meta.fitschar