J/A+A/712/A67ivo://CDS.VizieR/J/A+A/712/A67CDSXu W.Frey S.Cui L.Gabanyi K.E.2026-08-04T08:10:04Z2026-08-04T09:09:45ZCDS support team

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

cds-question@unistra.fractive-galactic-nucleiradio-sourcesvery-long-baseline-interferometryUGC 2369S is a luminous infrared galaxy (LIRG) undergoing a late-stage merger in a triple system, where the heavily obscured northern core is suspected to host an active galactic nucleus (AGN). However, severe dust and gas obscuration makes definitive confirmation challenging. We aim to provide direct observational evidence for the buried AGN through high-resolution radio imaging, while investigating the AGN accretion and feedback properties within this merger-driven gas-rich environment. We analyzed archival European VLBI Network (1.6GHz) and Very Long Baseline Array (1.7 and 5GHz) data of UGC 2369S. Through high-resolution imaging and visibility-domain Gaussian modeling, we characterized the morphology and intensity of its milliarcsecond-scale radio emission. A compact radio component is detected in the northern core, exhibiting high brightness temperatures (Tb>10^7^K) and a flat radio spectrum (alpha=-0.45), which confirms the presence of an obscured AGN. The sub-Eddington accretion rate ({lambda}_Edd_~2.7x10^-4^) indicates that it falls within the radiatively inefficient accretion flow state. We provide direct imaging evidence for an AGN in the northern core of UGC 2369S, revealing a deeply buried, jet-emitting low-luminosity AGN enshrouded by a Compton-thick gas cocoon. This demonstrates that VLBI is a uniquely effective tool for disentangling nuclear accretion and feedback processes within the heavily obscured environments of multiple-merger systems.2026A&A...712A..67Xhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/712/A67CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/712/A67https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/712/A67http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/712/A67https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/712/A67https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/712/A67http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/712/A67GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/712/A67/list (List of VLBI FITS images shown in Fig. 1)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/712/A67/list?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/712/A67/list?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/712/A67/list?GETtext/xml+votable180.050000true43.5075814.970810.0055555555555555566/231https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/712/A67?format=asciiRadiodefaultJ/A+A/712/A67/listList of VLBI FITS images shown in Fig. 1recnoRecord 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;obsnullableFreqObserved frequencyGHzem.freqdoublesizeSize of FITS fileKibytephys.size;meta.fitsintFileNameName of FITS file, in subdirectory fitsmeta.id;meta.fitscharTitleTitle of the FITS filemeta.title;meta.fitschar