J/A+A/684/A93ivo://CDS.VizieR/J/A+A/684/A93doi:10.26093/cds/vizier.36840093CDSLambert S.Secrest N.J.2024-11-29T20:02:09Z2024-04-09T10:02:31ZCDS support team

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

cds-question@unistra.frquasarsinterferometryastrometryThe stability of the International Celestial Reference Frame (ICRF), realized through geodetic very long baseline interferometry (VLBI) positions of thousands of extragalactic objects, is dependent on the individual positional stability of these objects. It has been recently shown that the prevalence of offsets between the VLBI positions of ICRF objects and their Gaia optical positions, which limit the optical-radio reference frame tie, is inversely correlated with optical photometric variability, suggesting that photometrically variable objects may be more positionally stable. In this work, we determine the relationship between VLBI position stability of ICRF objects and optical-radio position offsets as well as optical photometric variability. We created multi-epoch geodetic VLBI solutions for a sample of 520 ICRF sources that have sufficient data to determine the variability in their VLBI positions over time. We compared this position variability with the fractional photometric variability provided by the Gaia extragalactic source catalog, the Gaia-ICRF optical-radio position offsets, the uncertainty-normalized position offsets, and optical BP-RP color as well as with possible confounders such as optical magnitude, VLBI/Gaia position error, and redshift. We determined the relationship between VLBI position stability and gamma-ray detection by the Fermi Large Area Telescope (LAT), and we determined how the VLBI position and optical flux variabilities correlate with the spectral classification of our sample, considering flat spectrum radio quasars (FSRQs), quasi-stellar objects, BL Lacs, Seyfert, and gigahertz-peaked spectrum radio sources or compact-steep-spectrum radio sources. We found that VLBI astrometric variability is (i) negatively correlated with optical flux variability, (ii) positively correlated with optical-radio offsets, (iii) negatively correlated with optical color index BP-RP, and (iv) negatively correlated with gamma-ray detection. We also found that the most positionally stable sources are among the FSRQ and BL Lac classes. In other words, redder, photometrically variable sources have the most stable VLBI positions, the smallest optical-radio position offsets, and the highest rate of gamma-ray detection, and these sources tend to be spectrally classified as blazars. Our results are consistent with the most positionally stable sources being blazars, a class of object in which the jet is oriented close to the line of sight and where relativistic beaming increases photometric variability and minimizes the projected offset between the optical and radio positions. Our study should therefore orient future geodetic VLBI observing programs preferentially toward sources with high photometric variability because these sources are predicted to have better VLBI position stabilities and smaller optical-radio position offsets, improving the stability of the celestial reference frame axes.2024A&A...684A..93Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/684/A93CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/684/A93https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/684/A93http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/684/A93https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/684/A93https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/684/A93http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/684/A93GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/684/A93/table1 (Astrometric positional variability deduced from VLBI time series computed from the full geodetic VLBI data base along with the fractional variability taken from Gaia DR3)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/684/A93/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/684/A93/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/684/A93/table1?GETtext/xml+votable180.050000true1.1485644-47.60544560.0055555555555555566/60 307 376 438 532 572 583 700 839 911 1084-1085 1154 1419 1509 1546 1584 1622 1671 1782 2098 2143 2397 2404 2414 2531 2710 2836 2867 3024 3096 3309 3402 3675 3820 3886 3971 4027 4054 4352 4448 4572 4695-4696 4750 4820 4964 5139 5154 5163 5200 5306 5353 5371 5404 5458 5657 5693 5767 5848 5870 6033 6153 6164 6167 6252 6377 6448 6496 6507 6548 6641 6686 6716 6790 6853 6923 6996 7091 7181 7296 7351 7371 7389 7472 7570 7623 7642 7653 7709 7745 7851 7857 7969 8031 8057 8123 8207 8299 8345 8577 8615 8729 8805 8858 8915 9003 9075 9232 9248 9258 9442 9460 9512 9536 9588 9612 9618 9632-9633 9655 9676 9688 9723 9906 9976 9998 10006 10163 10170 10249-10250 10352 10422 10466 10474 10524 10548 10802-10803 11027 11094 11216 11279 11407 11461 11639 11715 11845 11880 12047 12218 12301 12352 12475 12505 12547 12580 12599 12604 12611 12842 12844 12918 13156 13230 13352 13410 13496 13545 13572 13693 13792 14150 14520 14737 14854 15023 15036 15494 15536 15819 15947 16027 16049 16057 16059 16113 16185 16261 16281 16592 16720 17110 17174 17212 17215 17351 17414 17516 17579 17734 17857 17909 17937 18002 18035 18084 18119 18214 18271 18378 18506 18561 18624 18669 18718 18755 18907 19088 19101 19223 19271 19308 19370 19436 19523 19567 19609 19622 19629 19872 19890 19918 20144 20213 20224 20476 20610 20657 20781 20836 20888 21049 21117 21121 21163 21266 21437 21564 21768 21905 21935 21960 21968 21972 21990 22396 22501 22558 22658-22659 22917 22950 22993 23014 23022 23121 23335 23383 23691 23761 23882 24084 24099-24100 24116 24123 24346 24568 24571 24608 24734 24809 24814 24845 25036 25196 25255-25256 25428 25501 25624 25630 25677 25742 25750 25864 25990 26000 26083 26100 26115 26303 26363 26550 26624 26946 26966 26983 27179 27220 27310 27322 27423 27436 27509 27514 27583 27909 27926 28042 28139 28167 28208 28383 28463 28479 28492 28628 28663 28673 28928 29016 29218 29570 29675 29795 29823 30075 30928 31176 31190 31334 31355 31391 31430 31451 31520 31529 31535 31559 31664 31857 31930 31986 32289 32311 32594 32660 32691 32764 32841 32916 32961 33043 33176 33406 33430 33560 33570 33684 33816 33825 33827 33829 33862 34013 34086 34099 34123 34210 34428 34461 34534 34571-34572 34675 34870-34871 34931 35079 35281 35294 35370 35432 35440 35651 35706 35801 35897 36005 36100 36151 36188 36333 36417 36554 36863 37032 37190 37217 37385 37474 37480 37779 37919 37994 38128 38189 38277 38311 38383 38416 38470 38579 38663 38734 38744 38763 38802 39664 39848 40344 40458 40479 40692 40730 40762 40766 40990 41033 41043 41072 41262 41275 41335 41460 41938 41942 42188 42726 42901 42980 43085 43366 43549 43822 43936 44043 44069 44147 44313 44614 44724 44776 44899 45011 45158 45178 45196 45393 45483 45614 45621 45648 45795 45843 46055 46251 46310 46337 46342 46373 46439 46448 46529 46546 46577 46588 46764 46798 46851 46887 46921 46932 46964 47014 47016 47080 47106 47151 47534 47540 47941 48023 48123 48142 48320 48362 48595 48610 48798 48846 48965 48985 490711.9867573869263685e-19 3.916500758235022e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/684/A93?format=asciidefaultJ/A+A/684/A93/table1Astrometric positional variability deduced from VLBI time series computed from the full geodetic VLBI data base along with the fractional variability taken from Gaia DR3recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIERSIERS B1950 name (HHMM+DDd)meta.id;meta.maincharAvarPositional variability from VLBI position time seriesmassrc.varfloatFvarFractional variability from Gaia DR3phot.mag;arith.ratiofloatOROptical-radio offsetmaspos;arith.difffloatNORNormalized optical-radio offsetpos;arith.difffloatSimbadSimbad column added by the CDSmeta.ref.urlcharGmagGaia DR3 G magnitudemagphot.mag;em.optfloatBP-RPGaia DR3 BP-RP color indexmagphot.color;em.opt.B;em.opt.RfloatClass[0/7]? Activity Type (1)src.classintnullableGamma? Gamma 1-100 GeV flux from Fermi-LAT 4FGL DR3ph.m**-2.s**-1phot.flux.density;em.gamma.harddoublenullablez? Redshift from NEDsrc.redshiftfloatnullablePEVLBISemi-major axis of the error ellipse from ICRF3masphys.angSize.smajAxis;pos.errorEllipsefloatPEGAIASemi-major axis of the error ellipse from Gaia DR3masphys.angSize.smajAxis;pos.errorEllipsefloat_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.main