J/ApJ/689/108ivo://CDS.VizieR/J/ApJ/689/108doi:10.26093/cds/vizier.16890108CDSLovell J.E.J.Rickett B.J.Macquart J.-P.Jauncey D.L.Bignall H.E.,Kedziora-Chudczer L.Ojha R.Pursimo T.Dutka M.Senkbeil C.,Shabala S.2017-09-29T09:03:51Z2011-02-01T14:21:46ZCDS support team

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

cds-question@unistra.fractive-galactic-nucleiinterstellar-mediumradio-continuum-emissionsurveysWe report on the variability of 443 flat-spectrum, compact radio sources monitored using the VLA for 3 days in four epochs at ~4 month intervals at 5GHz as part of the Micro-Arcsecond Scintillation-Induced Variability (MASIV) survey. Over half of these sources exhibited 2%-10% rms variations on timescales over 2 days. We analyzed the variations by two independent methods and find that the rms variability amplitudes of the sources correlate with the emission measure in the ionized interstellar medium along their respective lines of sight. We thus link the variations with interstellar scintillation of components of these sources, with some (unknown) fraction of the total flux density contained within a compact region of angular diameter in the range 10-50{mu}as. We also find that the variations decrease for high mean flux density sources and, most importantly, for high-redshift sources. The decrease in variability is probably due either to an increase in the apparent diameter of the source or to a decrease in the flux density of the compact fraction beyond z~2.2008ApJ...689..108Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/689/108CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toVIII/67 : Catalogue of scintillating radio sources (Artyukh+, 1996-1998)J/AZh/72/291 : Variability at Frequencies 3.9 and 7.5 GHz (Gorshkov+, 1995)J/MNRAS/325/1411 : ATCA Intraday Variability Survey (Kedziora-Chudczer+, 2001)J/AJ/128/1570 : 8.4GHz VLBA observations of scintillating sources (Ojha+,J/ApJS/165/439 : Interstellar scintillation at 2 and 8GHz (Rickett+, 2006)J/AZh/85/314 : Complete sample of flat-spectrum radio sources (Gorshkov+,https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/689/108https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/689/108http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/689/108https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/689/108https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/689/108http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/689/108GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/689/108/table2 (MASIV source variability characteristics)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/689/108/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/689/108/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/689/108/table2?GETtext/xml+votable180.050000true1.488208338.33752780.0055555555555555566/6 35 47 110 124 180 197 274 304 364 483 494 556 579 597 625 700 911 968 1001 1152 1154 1217 1233 1250 1403 1528 1584 1592 1593 1610 1616 1621 1622 1701 1709 1740 1741 1875 2053 2087 2093 2098 2121 2124 2213 2214 2223 2354 2397 2456 2531 2631 2710 2744 2836 2854 2861 2978 3002 3016 3024 3074 3096 3366 3506 3675 3774 3820 3841 3886 3977 4027 4122 4258 4405 4436 4446 4528 4544 4572 4644 4695 4696 4720 4754 4768 4770 4820 4944 5035 5139 5156 5163 5183 5340 5353 5413 5423 5448 5516 5539 5573 5693 5718 5808 5817 5848 5874 5880 5984 6025 6099 6164 6173 6252 6333 6335 6497 6505 6507 6513 6631 6641 6686 6716 6730 6741 6751 6774 6790 6821 6824 6829 6841 6853 6966 6996 7010 7030 7099 7129 7148 7207 7227 7235 7346 7389 7456 7569 7570 7619 7623 7649 7653 7707 7709 7724 7743 7782 7874 7911 7937 7951 8031 8057 8073 8106 8112 8131 8199 8324 8341 8380 8464 8526 8580 8588 8615 8716 8717 8772 8773 8793 8805 8830 8853 9011 9016 9062 9159 9165 9204 9248 9403 9442 9460 9483 9526 9536 9545 9560 9588 9632 9633 9641 9671 9672 9676 9681 9685 9688 9723 9786 9813 9853 9860 9961 9976 10163 10198 10249 10321 10330 10352 10395 10422 10435 10524 10548 10550 10624 10803 10983 11037 11049 11185 11216 11279 11398 11409 11430 11574 11640 11642 11706 11759 11805 11821 11845 11878 11977 12001 12133 12139 12301 12308 12311 12352 12397 12444 12474 12475 12619 12621 12851 13273 13277 13352 13410 13414 13427 13447 13537 13576 13578 13609 13664 13731 13739 13792 14338 14495 14605 14634 14737 14820 14842 14854 14985 14996 15012 15123 15271 15277 15522 15525 15536 15594 15819 15822 15936 15945 15947 16049 16113 16170 16281 16298 16351 17791 17890 18035 18160 18209 18214 18361 18378 18806 18875 18923 18931 19101 19166 19170 19174 19189 19190 19217 19287 19298 19308 19357 19363 19593 19622 19629 19676 19726 19743 19765 19872 19890 19918 20009 20017 20099 20117 20141 20146 20184 20218 20468 21885 21935 21960 21968 21972 21991 22350 22354 22359 22363 22364 22375 22396 22433 22501 22943 22963 22965 23014 23015 23226 23274 23306 23416 23437 23462 23478 23552 23563 23730 23783 23786 23820 23882 24063 24084 24099 24123 24258 25949 25975 26301 26303 26309 26409 26502 26529 26550 27060 27061 27310 27322 27323 27423 27521 27523 27581 27583 27595 27605 27705 27841 27909 27920 27934 28003 28097 28305 28356 28383 28453 28454 28479 28492 28558 28584 28607 28652 30484 30542 30557 31079 31143 31154 31190 31202 31211 31229 31391 31430 31451 31520 31527 31529 31534 31649 31664 31745 31792 31817 31844 31857 31894 32035 32101 32247 32311 32325 32328 32358 32362 32380 32391 32440 32583 32607 327643.313034785154005e-24 3.313034785154005e-24https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/689/108?format=asciiRadiodefaultJ/ApJ/689/108/table2MASIV source variability characteristicsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMASIVSource identification (JHHMM+DDMM)meta.id;meta.maincharHaWHAM H{alpha} flux in Rayleighs1e+10ph.m**-2.s**-1phot.flux;em.line.Halphafloat<S1>Mean epoch 1 (2002.05) 5GHz flux density (G1)Jyphot.flux.density;em.radio.3-6GHzfloat<S2>Mean epoch 2 (2002.35) 5GHz flux density (G1)Jyphot.flux.density;em.radio.3-6GHzfloat<S3>Mean epoch 3 (2002.70) 5GHz flux density (G1)Jyphot.flux.density;em.radio.3-6GHzfloat<S4>Mean epoch 4 (2003.02) 5GHz flux density (G1)Jyphot.flux.density;em.radio.3-6GHzfloatmod1Raw epoch 1 (2002.05) modulation index (G1)%src.var.indexfloatmod2Raw epoch 2 (2002.35) modulation index (G1)%src.var.indexfloatmod3Raw epoch 3 (2002.70) modulation index (G1)%src.var.indexfloatmod4Raw epoch 4 (2003.02) modulation index (G1)%src.var.indexfloate_modThe 1{sigma} error in raw modulation index%stat.errorfloatC1[ync] variable (y) for epoch 1 (1)meta.code;src.varcharC2[ync] variable (y) for epoch 2 (1)meta.code;src.varcharC3[ync] variable (y) for epoch 3 (1)meta.code;src.varcharC4[ync] variable (y) for epoch 4 (1)meta.code;src.varcharD(2d)Standard characterization of intra-day variation from fit to epoch average structure functionsrc.var.indexdoublee_D(2d)? Error in D(2d) (2)stat.errorfloatnullabletauTimescale classification (3)meta.code.classintNEDSimbad column added by the CDScharRAJ2000Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of Declination (J2000)pos.eq.dec;meta.main