J/A+A/342/378ivo://CDS.VizieR/J/A+A/342/378doi:10.26093/cds/vizier.33420378CDSGurvits L.I.Kellermann K.I.Frey S.1999-02-23T10:52:13Z1999-02-23T11:51:37ZCDS support team

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

cds-question@unistra.fractive-galactic-nucleiquasarsradio-galaxiesredshiftedradio-sourcesvery-long-baseline-interferometryWe discuss the "angular size-redshift" relation for compact radio sources distributed over a wide range of redshifts 0.011<=z<=4.72. Our study is based on a sample of 330 5 GHz VLBI contour maps taken from the literature. Unlike extended source samples, the "angular size - redshift" relation for compact radio sources appears consistent with the predictions of standard Friedmann world models with q_0_=~0.5 without the need to consider evolutionary or selection effects due to a "linear size-luminosity" dependence. By confining our analysis to sources having a spectral index, -0.38<={alpha}<=0.18, and a total radio luminosity, Lh^2^>= 10^26^W/Hz (H_0_=100hkm/s/Mpc, q_0_=0.5 used as a numerical example), we are able to restrict the dispersion in the "angular size-redshift" relation. The best fitting regression analysis in the framework of the Friedmann-Robertson-Walker model gives the value of the deceleration parameter q_0_=0.21+/-0.30 if there are no evolutionary or selection effects due to a "linear size-luminosity", "linear size-redshift" or "linear size-spectral index" dependence.1999A&A...342..378Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/342/378CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/342/378https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/342/378http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/342/378https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/342/378https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/342/378http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/342/378GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapRadiodefaultJ/A+A/342/378/table1"VLBI angular size - z" for 330 sourceszRedshiftsrc.redshiftfloatr_VLBIVLBI reference in refs.dat filemeta.refcharSISpectral indexspect.indexfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIAUIAU name (based on 1950 position)meta.id;meta.maincharNameAlternative namemeta.idcharType[BGQ] Type of the optical counterpart (1)src.classcharS6cmFlux density at 6 cm from Gregory et al. (1996) unless otherwise stated.Jyphot.flux.density;em.radio.3-6GHzfloatn_S6cm[q] Note on S6cm (2)meta.notecharS20cm? Flux density at 20 cm (or alternative) from White and Becker (1992) unless otherwise statedJyphot.flux.density;em.radio.1500-3000MHzfloatnullablen_S20cm[f-y] Note on S20cm (2)meta.notecharl_thetaSymbol of an upper limitmeta.code.errorcharthetaAngular sizemasphys.angSize;srcfloatStruc[CJLS] Structure code (3)meta.code;src.morphcharr_zRedshift reference in refs.dat filemeta.refcharr_S6cm6cm flux density reference in refs.dat filemeta.refcharr_S20cm20cm flux density reference in refs.dat filemeta.refcharJ/A+A/342/378/refsReferencesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRefReference codemeta.bib.bibcodecharBibCodeBibCodemeta.bib.bibcodecharAutAuthor's namemeta.bib.authorcharCommCommentsmeta.notechar