J/A+A/694/A176ivo://CDS.VizieR/J/A+A/694/A176doi:10.26093/cds/vizier.36940176CDSUlgiati A.Paiano S.Pintore F.Russell T.D..Sbarufatti B.Pinto C.,Ambrosi E.D'Ai A.Cusumano G.Del Santo M.2025-05-21T20:01:36Z2025-02-12T10:48:04ZCDS support team

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

cds-question@unistra.frgamma-ray-astronomyactive-galactic-nucleix-ray-sourcesradio-sourcesIn this paper, we searched for multi-wavelength (X-ray, optical and radio) counterparts to the unassociated gamma-ray sources (UGS) of the Fermi 4FGL-DR4 catalog. The main goal is to identify new blazars and/or new active galactic nuclei (AGNs) emitting at GeV energies [like (Narrow Line) Seyfert-1 and radio galaxies]. We focus on sky regions observed by the Swift satellite that overlap with the reported positions of the UGSs. Since our primary interest lies in extra-galactic sources, we focus on UGSs located outside the Galactic plane (|b|>10{deg}). Due to the large number of sources (about 1800 UGS), we developed a pipeline to automatised the search for counterparts and significantly reduce the computational time for the analysis. Our association process begins by identifying potential X-ray counterparts for each UGS; if one is found, we further look for corresponding radio and optical counterparts in the X-ray counterpart error box, thus minimizing ambiguities. Out of the 1284 UGSs in the 4FGL-DR4 catalog, 714 were observed at east once by Swift/XRT. We detected, with a significance of >=3{sigma}, at least one X-ray source within the Fermi error box for 274 of these gamma-ray emitters. Among these, 193 UGSs have a single potential X-ray counterpart (referred to as UGS1), while 81 have multiple potential X-ray counterparts within the Fermi error box (referred to as UGS2). Of the UGS2, 54 have two X-ray counterparts, 11 have three, and the remaining 16 have more than three. Each UGS1 has an optical counterpart, and 113 also could be associated to a radio counterpart. We performed a comparison of the possible counterpart properties with those of the gamma-ray emitters identified by Fermi, with the aim to assess the goodness of our associations.2025A&A...694A.176Uhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/694/A176CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toIX/67 : Incremental Fermi LAT 4th source cat. (4FGL-DR3) (Fermi-LAT col., 2022)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/694/A176https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/694/A176http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/694/A176https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/694/A176https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/694/A176http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/694/A176GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/694/A176/table1 (Information about the Swift/XRT detections within the 3{sigma} Fermi error box of UGS1 sample (UGS with a single potential X-ray counterpart))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/694/A176/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/694/A176/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/694/A176/table1?GETtext/xml+votable180.050000true1.011131.03880.005555555555555556Cone search capability for table J/A+A/694/A176/table2 (Information about the Swift/XRT detections within the 3{sigma} Fermi error box of UGS2 sample (UGS with more than one potential X-ray)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/694/A176/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/694/A176/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/694/A176/table2?GETtext/xml+votable180.050000true4.2859-46.10210.005555555555555556Cone search capability for table J/A+A/694/A176/table5 (MWL counterparts of UGS1 sample)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/694/A176/table5?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/694/A176/table5?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/694/A176/table5?GETtext/xml+votable180.050000true1.010531.03940.005555555555555556Cone search capability for table J/A+A/694/A176/table6 (MWL counterparts of UGS2 sample)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/694/A176/table6?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/694/A176/table6?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/694/A176/table6?GETtext/xml+votable180.050000true4.2862-46.10190.0055555555555555566/50 760 836 973 1045 1153 1185 1531 1538 1597 1684 1998 2142 2167 2280 2324 2681 2748 2886 3105 3113 4074 4376 4911 4922 5193 5317 5415 5421 5583 5606 5800 6073 6477 6667 6764 7027 7092 7137 7237 7448 7531 7743 7759 7940 7958 8010-8011 8042 8279 8556 8603 8733 9195 9198 9321 9379 9642 9731 9759 9773 9877 9914 10011 10468 11091 11156 11265 11268 11572 11964-11965 12164 12523 12668 12730 13097 13124 13368 13370 13452 13765 14856 14877 15043 15160 15183 15304 15604 16044 16137 16182 16226 16231-16232 16254 16284 16385 16541 16560 16648-16650 16686 16851 16880-16881 17223 17270 17734 18333 18343 18409 18626 18815 18934 18991 19084 19135 19193 19195 19431 19685 19696 20078 20188 20221 20381 20398 20417 20588 21385 21392 21394 21399 21401 21496 21800 21856 21903 22341 22482 22884 23427 23717 23728 23739 24726 24788-24789 25003 25095 25142 25262 25381 25403 25512 25525 25693 25971 25974 26237 26628 26767 26933 27074 27080 27155 27964 28172 29042-29043 29374 30013 30024 30028 30196 30202 31122 31460 31868 32379 32394 32420 32578 32742 32909 33059 33206 33305 33341 33482 33514 33596 33795 33801 33984 34053 34216 34386 34860 34871 34949 35029 35240 35343 35361 35374 35395 35482 35637 35739 35873 36128 36394 36445 36484-36485 36901 37003 37025 37629 38176 38178 38195 38488 38492 38837 39091 39114 39139 39157 39431 39439 39459 39591 39602 40164 40366 40808 41091 41105 41253 41340 42635 42989 43197 43229 43278 43350 43600 43657 43751 43856 43860 43863 44040 44129 44571 44634 44741 44751 44986 45077 45079 45375 45492 45707 45736 45754 45859 45874 45904 45974 45980 45998 46209 46239 46342 46424 46444 46480 46622 47245 47392 47460 47800 47857 47912 48194 48200 48269 48306 48707 48898https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/694/A176?format=asciiGamma-rayX-rayRadiodefaultJ/A+A/694/A176/table1Information about the Swift/XRT detections within the 3{sigma} Fermi error box of UGS1 sample (UGS with a single potential X-ray counterpart)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSimbadSimbad column added by the CDSmeta.ref.urlcharUGS4FGL namemeta.id;meta.maincharSiggammagamma-ray detection, in sigma unitstat.fit.goodnessfloatTexpSwift exposure timekstime.duration;obs.exposurefloatXRTSwift/XRT source namemeta.idcharRAJ2000Right Ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainePosPositional errorarcsecstat.error;posfloatSigXRTX-ray detection significance, in sigma unitstat.fit.goodnessfloatJ/A+A/694/A176/table2Information about the Swift/XRT detections within the 3{sigma} Fermi error box of UGS2 sample (UGS with more than one potential X-raySimbadSimbad column added by the CDSmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintUGS4FGL namemeta.id;meta.maincharSiggammagamma-ray detection, in sigma unitstat.fit.goodnessfloatTexpSwift exposure timekstime.duration;obs.exposurefloatXRTSwift/XRT source namemeta.idcharRAJ2000Right Ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainePosPositional errorarcsecstat.error;posfloatSigXRTX-ray detection significance, in sigma unitstat.fit.goodnessfloatJ/A+A/694/A176/table3Results of the X-ray spectral fitting for UGS1 samplerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintUGS4FGL namemeta.id;meta.maincharXRTSwift/XRT sourcemeta.idcharCrateCount rate0.001count.s**-1phot.count;em.X-rayfloate_CrateLower limit count rate0.001count.s**-1stat.error;phot.countfloatE_CrateUpper limit count rate0.001count.s**-1stat.error;stat.maxfloatnHEquivalent hydrogen column density1e+20cm**-2phys.columnDensityfloatGAMMAPower-law indexmeta.code;spect.indexfloate_GAMMA? Lower limit power-law indexstat.errorfloatnullableE_GAMMA? Upper limit power-law indexstat.error;stat.maxfloatnullableNormNormalization factorph.keV**-1.cm**-2.s**-1stat.fit.paramfloate_NormLower limit normalization factorph.keV**-1.cm**-2.s**-1stat.errorfloatE_NormUpper limit normalization factorph.keV**-1.cm**-2.s**-1stat.error;stat.maxfloatFabsAbsorbed flux in the range 0.3-10keVmW.m**-2phot.flux;em.X-rayfloate_FabsLower limit absorbed flux in the range 0.3-10keVmW.m**-2stat.errorfloatE_FabsUpper limit absorbed flux in the range 0.3-10 keVmW.m**-2stat.error;stat.maxfloatchi2n? chi^2^_n_ valuestat.fit.chi2floatnullabledof? Relative degrees of freedomstat.fit.dofintnullableJ/A+A/694/A176/table4Results of the X-ray spectral fitting for UGS2 sampleE_GAMMA? Upper limit power-law indexstat.error;stat.maxfloatnullableNormNormalization factorph.keV**-1.cm**-2.s**-1stat.fit.paramfloate_NormLower limit normalization factorph.keV**-1.cm**-2.s**-1stat.errorfloatE_NormUpper limit normalization factorph.keV**-1.cm**-2.s**-1stat.error;stat.maxfloatFabsAbsorbed flux in the range 0.3-10keVmW.m**-2phot.flux;em.X-rayfloate_FabsLower limit absorbed flux in the range 0.3-10keVmW.m**-2stat.errorfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintUGS4FGL namemeta.id;meta.maincharXRTSwift/XRT sourcemeta.idcharCrateCount rate0.001count.s**-1phot.count;em.X-rayfloate_CrateLower limit count rate0.001count.s**-1stat.error;phot.countfloatE_CrateUpper limit count rate0.001count.s**-1stat.error;stat.maxfloatnHEquivalent hydrogen column density1e+20cm**-2phys.columnDensityfloatGAMMAPower-law indexmeta.code;spect.indexfloate_GAMMA? Lower limit power-law indexstat.errorfloatnullableE_FabsUpper limit absorbed flux in the range 0.3-10 keVmW.m**-2stat.error;stat.maxfloatchi2n? chi^2^_n_ valuestat.fit.chi2floatnullabledof? Relative degrees of freedomstat.fit.dofintnullableJ/A+A/694/A176/table5MWL counterparts of UGS1 samplerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintUGS4FGL namemeta.id;meta.maincharXRTSwift/XRT sourcemeta.idcharn_XRT[*] * for sources with proper motionmeta.notecharRadRadio sourcemeta.idcharOptOptical sourcemeta.idcharRAJ2000? Right Ascension of optical counterpart (J2000)degpos.eq.ra;meta.mainnullableDEJ2000? Declination of optical counterpart (J2000)degpos.eq.dec;meta.mainnullablegmag? g magnitude of the optical sourcemagphot.mag;em.opt.Bfloatnullablermag? r magnitude of the optical sourcemagphot.mag;em.opt.RfloatnullableFopt? Optical density fluxmW.m**-2.Hz**-1phot.flux.density;em.optdoublenullablel_Fradlimit flag on Fradmeta.code.errorcharFrad? Radio density fluxmJyphot.flux.density;em.radiofloatnullablel_RLimit flag n Rmeta.code.errorcharR? Radio-loudness parameterphot.flux;arith.ratiointnullableJ/A+A/694/A176/table6MWL counterparts of UGS2 samplerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintUGS4FGL namemeta.id;meta.maincharXRTSwift/XRT sourcemeta.idcharn_XRT[*] * for sources with proper motionmeta.notecharRadRadio sourcemeta.idcharOptOptical sourcemeta.idcharRAJ2000? Right Ascension of optical counterpart (J2000)degpos.eq.ra;meta.mainnullableDEJ2000? Declination of optical counterpart (J2000)degpos.eq.dec;meta.mainnullablegmag? g magnitude of the optical sourcemagphot.mag;em.opt.Bfloatnullablermag? r magnitude of the optical sourcemagphot.mag;em.opt.RfloatnullableFopt? Optical density fluxmW.m**-2.Hz**-1phot.flux.density;em.optdoublenullablel_Fradlimit flag on Fradmeta.code.errorcharFrad? Radio density fluxmJyphot.flux.density;em.radiofloatnullablel_RLimit flag n Rmeta.code.errorcharR? Radio-loudness parameterphot.flux;arith.ratiointnullable