J/other/Galax/12ivo://CDS.VizieR/J/other/Galax/12.25CDSSotnikova YMikhailov AMufakharov TAn TKudryavtsev DMingaliev M,Udovitskiy RKudryashova AStolyarov VSemenova T.2024-11-28T16:24:11Z2024-06-03T11:49:21ZCDS support team

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

cds-question@unistra.frquasarsredshiftedradio-sourcesWe present a study of the radio variability of bright, S_1.4_>=100mJy, high-redshift quasars at z?=3 on timescales of up to 30-40 yrs. The study involved simultaneous RATAN-600 measurements at the frequencies of 2.3, 4.7, 8.2, 11.2, and 22.3GHz in 2017-2020. In addition, data from the literature were used. We have found that the variability index, V_S_, which quantifies the normalized difference between the maximum and minimum flux density while accounting for measurement uncertainties, ranges from 0.02 to 0.96 for the quasars. Approximately half of the objects in the sample exhibit a variability index within the range from 0.25 to 0.50, which is comparable to that observed in blazars at lower redshifts. The distribution of V_S_ at 22.3GHz is significantly different from that at 2.3-11.2GHz, which may be attributed to the fact that a compact AGN core dominates at the source's rest frame frequencies greater than 45GHz, leading to higher variability indices obtained at 22.3GHz (the V_S_ distribution peaks around 0.4) compared to the lower frequencies (the V_S_ distribution at 2.3 and 4.7GHz peaks around 0.1-0.2). Several source groups with distinctive variability characteristics were found using the cluster analysis of quasars. We propose seven new candidates for gigahertz-peaked spectrum (GPS) sources and five new megahertz-peaked spectrum (MPS) sources based on their spectrum shape and variability features. Only 6 out of the 23 sources previously reported as GPS demonstrate a low variability level typical of classical GPS sources (V_S_<0.25) at 4.7-22.3GHz. When excluding the highly variable peaked-spectrum blazars, we expect no more than 20% of the sources in the sample to be GPS candidates and no more than 10% to be MPS candidates.2024Galax..12...25Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/other/Galax/12.25CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/other/Galax/12.25https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/other/Galax/12.25http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/other/Galax/12.25https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/other/Galax/12.25https://vizier.iucaa.in/viz-bin/votable?-source=J/other/Galax/12.25http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/other/Galax/12.25GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/other/Galax/12.25/tablea2 (Variability estimates for 101 quasars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/other/Galax/12.25/tablea2?https://vizier.iucaa.in/viz-bin/conesearch/J/other/Galax/12.25/tablea2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/other/Galax/12.25/tablea2?GETtext/xml+votable180.050000true0.285923119.24272280.0055555555555555566/594 638 2112 2469 2820 3074 4114 4120 4263 4361 4446 4720 4947 5130 5170 5229 5362 5392 5470 6217 6469 6576 6790 6853 8218 8229 8255 8345 8525 8588 8627 8748 8912 9161 9334 9394 10328 10463 10558 10598 10603 10690 10694 10802 12471 12804 12888 13213 13314 14905 17326 17859 18164 18271 18644 18883 18988 19061 19673 19882 20156 20450 20657 21020 22298 23099 23257 23355 23548 25413 25677 25863 25990 26083 26816 27033 27302 27549 27608 28004 28369 29795 30836 31146 31355 31383 31529 32410 32451 32746 34271 35741 35770 35952 36346 44724 46577 47050 47941 48610 48708https://cdsarc.cds.unistra.fr/viz-bin/moc/J/other/Galax/12.25?format=asciiRadiodefaultJ/other/Galax/12.25/tablea2Variability estimates for 101 quasarsSimbadNameSimbad column added by the CDSmeta.idcharnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameName of the source (JHHMM+DDMM, J2000)meta.id;meta.maincharzredshiftsrc.redshiftfloatl_t4.7Limit flag on t4.7meta.code.errorchart4.7Timescale of variability at 4.7 GHztime.scaleintN4.7Number of observational epochs at 4.7 GHzmeta.numberintl_t22.3Limit flag on t22.3meta.code.errorchart22.3? Timescale of variability at 22.3 GHztime.scaleintnullableN22.3? Number of observational epochs at 22.3 GHzmeta.numberintnullableV2.3? Variability index at 2.3 GHzsrc.var.indexfloatnullableM2.3? Modulation index at 2.3 GHzsrc.var.indexfloatnullableF2.3? Fractional variability index at 2.3 GHzsrc.var.indexfloatnullableV4.7Variability index at 4.7 GHzsrc.var.indexfloatM4.7Modulation index at 4.7 GHzsrc.var.indexfloatF4.7? Fractional variability index at 4.7 GHzsrc.var.indexfloatnullableV8.2? Variability index at 8.2 GHzsrc.var.indexfloatnullableM8.2? Modulation index at 8.2 GHzsrc.var.indexfloatnullableF8.2? Fractional variability index at 8.2 GHzsrc.var.indexfloatnullableV11.2? Variability index at 11.2 GHzsrc.var.indexfloatnullableM11.2? Modulation index at 11.2 GHzsrc.var.indexfloatnullableF11.2? Fractional variability index at 11.2 GHzsrc.var.indexfloatnullableV22.3? Variability index at 22.3 GHzsrc.var.indexfloatnullableM22.3? Modulation index at 22.3 GHzsrc.var.indexfloatnullableF22.3? Fractional variability index at 22.3 GHzsrc.var.indexfloatnullable_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