J/ApJ/793/115ivo://CDS.VizieR/J/ApJ/793/115doi:10.26093/cds/vizier.17930115CDSBouwens R.J.Illingworth G.D.Oesch P.A.Labbe I.van Dokkum P.G.,Trenti M.Franx M.Smit R.Gonzalez V.Magee D.2019-12-27T04:35:35Z2017-05-12T15:46:50ZCDS support team

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

cds-question@unistra.frgalaxiesphotometryhst-photometryultraviolet-photometryredshiftedWe measure the UV-continuum slope {beta} for over 4000 high-redshift galaxies over a wide range of redshifts z~4-8 and luminosities from the HST HUDF/XDF, HUDF09-1, HUDF09-2, ERS, CANDELS-N, and CANDELS-S data sets. Our new {beta} results reach very faint levels at z~4 (-15.5 mag: 0.006 L_z=3_^*^), z~5 (-16.5 mag: 0.014 L_z=3_^*^), and z~6 and z~7 (-17 mag: 0.025 L_z=3_^*^). Inconsistencies between previous studies led us to conduct a comprehensive review of systematic errors and develop a new technique for measuring {beta} that is robust against biases that arise from the impact of noise. We demonstrate, by object-by-object comparisons, that all previous studies, including our own and those done on the latest HUDF12 data set, suffered from small systematic errors in {beta}. We find that after correcting for the systematic errors (typically {Delta}{beta}~0.1-0.2) all {beta} results at z~7 from different groups are in excellent agreement. The mean {beta} we measure for faint (-18 mag: 0.1L_z=3_^*^) z~4, z~5, z~6, and z~7 galaxies is -2.03+/-0.03+/-0.06 (random and systematic errors), -2.14+/-0.06+/-0.06, -2.24+/-0.11+/-0.08, and -2.30+/-0.18+/-0.13, respectively. Our new {beta} values are redder than we have reported in the past, but bluer than other recent results. Our previously reported trend of bluer {beta}'s at lower luminosities is confirmed, as is the evolution to bluer {beta}'s at high redshifts. {beta} appears to show only a mild luminosity dependence faintward of M_UV, AB_~-19 mag, suggesting that the mean {beta} asymptotes to ~-2.2 to -2.4 for faint z>=4 galaxies. At z~7, the observed {beta}'s suggest non-zero, but low dust extinction, and they agree well with values predicted in cosmological hydrodynamical simulations.2014ApJ...793..115Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/793/115CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJ/653/53 : z~6 galaxies UV luminosity function (Bouwens+, 2006)J/AJ/141/14 : HST WFC3 ERS : emission-line galaxies (Straughn+, 2011)J/ApJ/743/146 : HST/WFC3 observations in HUDF and GOODS-S (Cameron+, 2011)J/ApJ/756/164 : UV galaxies in CANDELS from z=8 to z=4 (Finkelstein+, 2012)J/MNRAS/453/1136 : XDF CHEF photometric catalogue (Jimenez-Teja+, 2015)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/793/115https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/793/115http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/793/115https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/793/115https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/793/115http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/793/115GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/793/115/table8 (A complete list of the UV-continuum slopes beta measures for sources in our z~4, z~5, z~6, z~7, and z~8 samples)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/793/115/table8?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/793/115/table8?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/793/115/table8?GETtext/xml+votable180.050000true53.1615-27.80753060.0055555555555555566/11252 35935https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/793/115?format=asciiUVdefaultJ/ApJ/793/115/table8A complete list of the UV-continuum slopes beta measures for sources in our z~4, z~5, z~6, z~7, and z~8 samplesIDSource IDmeta.id;meta.maincharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of Declination (J2000)pos.eq.dec;meta.mainUVMagAbsolute AB magnitude in the Rest-frame UVmagphys.magAbsfloatbetaUV-continuum slope betaspect.indexfloate_betaUncertainty in the UV-continuum slope betastat.errorfloatrset[4/8] Sample (1)src.sampleintdset[1/4] Data Set (2)meta.idintJ/ApJ/793/115/table9Complete set of flux measurements used to derive beta for our z~4, z~5, z~6, z~7, and z~8 samplesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDSource IDmeta.id;meta.mainchariflux? F775W Flux Measurement; 100 pJyphot.flux.density;em.IR.60-100umintnullablee_iflux? Uncertainty in ifluxstat.errorintnullableIflux? F814W Flux Measurement; 100 pJyphot.flux;em.opt.Iintnullablee_Iflux? Uncertainty in Ifluxstat.errorintnullablezflux? F850LP Flux Measurement; 100 pJyphot.flux.density;em.IR.60-100umintnullablee_zflux? Uncertainty in zfluxstat.errorintnullableyflux? F098M Flux Measurement; 100 pJyphot.flux.density;em.IR.60-100umintnullablee_yflux? Uncertainty in yfluxstat.errorintnullableYflux? F105W Flux Measurement; 100 pJyphot.flux.density;em.IR.60-100umintnullablee_Yflux? Uncertainty in Yfluxstat.errorintnullableJflux? F125W Flux Measurement; 100 pJyphot.flux.density;em.IR.Jintnullablee_Jflux? Uncertainty in Jfluxstat.errorintnullableJHflux? F140W Flux Measurement; 100 pJyphot.flux.density;em.IR.Hintnullablee_JHflux? Uncertainty in JHfluxstat.errorintnullableHflux? F160W Flux Measurement; 100 pJyphot.flux.density;em.IR.Hintnullablee_Hflux? Uncertainty in Hfluxstat.errorintnullable