J/A+A/618/A85ivo://CDS.VizieR/J/A+A/618/A85doi:10.26093/cds/vizier.36180085CDSSchreiber C.Glazebrook K.Nanayakkara T.Kacprzak G.G.Labbe I.,Oesch P.Yuan T.Tran K.-V.Papovich C.Spitler L.Straatman C.2020-01-13T12:10:56Z2018-10-23T08:06:19ZCDS support team

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

cds-question@unistra.frgalaxiescatalogsredshiftedWe present Keck-MOSFIRE H and K spectra for a sample of 24 candidate quiescent galaxies at 3<z<4, identified from their rest-frame UVJ colors and photometric redshifts in the ZFOURGE and 3DHST surveys. With median integration times of one hour in H and five in K, we obtain spectroscopic redshifts for half of the sample, using either Balmer absorption lines or nebular emission lines. We confirm the high accuracy of the photometric redshifts for this spectroscopically-confirmed sample, with a median |Zphot-Zspec|/(1+Zspec) of 1.2%. Two galaxies turn out to be dusty H{alpha} emitters at lower redshifts (z<2.5), and these are the only two detected in the sub-mm with ALMA. High equivalent-width [OIII] emission is observed in two galaxies, contributing up to 30% of the K-band flux and mimicking the UVJ colors of an old stellar population. This implies a failure rate of only 20% for the UVJ selection at these redshifts. Lastly, Balmer absorption features are identified in four galaxies, among the brightest of the sample, confirming the absence of OB stars. We then modeled the spectra and photometry of all quiescent galaxies with a wide range of star-formation histories. We find specific star-formation rates (sSFR) lower than 0.15Gyr^-1^ (a factor of ten below the main sequence) for all but one galaxy, and lower than 0.01Gyr^-1^ for half of the sample. These values are consistent with the observed H{beta} and [OII] luminosities, and the ALMA non-detections. The implied formation histories reveal that these galaxies have quenched on average 300Myr prior to being observed, between z=3.5 and 5, and that half of their stars were formed by z~5.5 with a mean SFR~300M_{sun}_/yr. We finally compared the UVJ selection to a selection based instead on the sSFR, as measured from the photometry. We find that galaxies a factor of ten below the main sequence are 40% more numerous than UVJ-selected quiescent galaxies, implying that the UVJ selection is pure but incomplete. Current models fail at reproducing our observations, and underestimate either the number density of quiescent galaxies by more than an order of magnitude, or the duration of their quiescence by a factor two. Overall, these results confirm the existence of an unexpected population of quiescent galaxies at z>3, and offer the first insights on their formation histories.2018A&A...618A..85Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/618/A85CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/618/A85https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/618/A85http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/618/A85https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/618/A85https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/618/A85http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/618/A85GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/618/A85/sample (Physical properties (tabnle 3) and spectroscopic redshifts (table A4) of the galaxies)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/618/A85/sample?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/618/A85/sample?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/618/A85/sample?GETtext/xml+votable180.050000true150.112562.37652660.0055555555555555566/11425 17679 17690 27258https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/618/A85?format=asciidefaultJ/A+A/618/A85/samplePhysical properties (tabnle 3) and spectroscopic redshifts (table A4) of the galaxiesSimbadNameSimbad column added by the CDSmeta.idcharzRedshiftsrc.redshiftfloatV-JV-J color (AB)magphot.color;em.opt.V;em.IR.JfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDComposite ID of the galaxy, with format "CATALOG-FIELD-ID" (G1)meta.id;meta.maincharRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainf_z[0/2] Redshift flag (2)meta.codechare_zUpper uncertainty on redshiftstat.error;src.redshiftfloatE_zLower uncertainty on redshiftstat.error;stat.maxfloatU-VU-V color (AB)magphot.color;em.opt.U;em.opt.Vfloate_U-VUpper uncertainty on U-V colormagstat.error;phot.color;em.opt.UfloatE_U-VLower uncertainty on U-V colormagstat.error;stat.maxfloate_V-JUpper uncertainty on V-J colormagstat.error;phot.color;em.opt.VfloatE_V-JLower uncertainty on V-J colormagstat.error;stat.maxfloatMassStellar mass in solar units1e+10solMassphys.massfloate_MassUpper uncertainty on stellar mass1e+10solMassstat.error;phys.massfloatE_MassLower uncertainty on stellar mass1e+10solMassstat.error;stat.maxfloatAvAttenuation in the V bandmagphys.absorptionfloate_AvUpper uncertainty on attenuationmagstat.errorfloatE_AvLower uncertainty on attenuationmagstat.error;stat.maxfloatSFRPast star-formation rate averaged over 10MyrsolMass/yrphys.SFRfloate_SFRUpper uncertainty on SFRsolMass/yrstat.error;phys.SFRfloatE_SFRLower uncertainty on SFRsolMass/yrstat.error;stat.maxfloattqDuration of quiescenceGyrtime.intervalfloate_tqUpper uncertainty on quiescenceGyrstat.errorfloatE_tqLower uncertainty on quiescenceGyrstat.error;stat.maxfloatzfFormation redshiftstat.fit.paramfloate_zfUpper uncertainty on formation redshiftstat.errorfloatE_zfLower uncertainty on formation redshiftstat.error;stat.maxfloattsfDuration of star-forming phaseGyrtime.intervalfloate_tsfUpper uncertainty on SF durationGyrstat.errorfloatE_tsfLower uncertainty on SF durationGyrstat.error;stat.maxfloatlogSFRpPast average star-formation rate during SF phase (log)log(solMass.yr**-1)phys.SFRfloate_logSFRpUpper uncertainty on past average SFR (log)log(solMass.yr**-1)stat.errorfloatE_logSFRpLower uncertainty on past average SFR (log)log(solMass.yr**-1)stat.error;stat.maxfloatf_zsSpectroscopic redshift flag (2)meta.codecharzpPhotometric redshiftsrc.redshift.photfloate_zpUpper uncertainty on photometric redshiftstat.errorfloatE_zpLower uncertainty on photometric redshiftstat.error;stat.maxfloatzsSpectroscopic redshiftsrc.redshift;pos.heliocentricfloate_zsUpper uncertainty on spectroscopic redshiftstat.errorfloatE_zsLower uncertainty on spectroscopic redshiftstat.error;stat.maxfloatdeltazSignificance of "zp-zs"stat.fit.goodnessfloatpzProbability that true redshift is within +/-0.01 of zs%statintchi2Reduced chi squared of the fitstat.fit.chi2;stat.fit.param;meta.modelledfloatBalmerBalmer absorption flag (3)meta.codecharsigma? Velocity dispersionkm/sphys.veloc.dispersionintnullablee_sigma? Uncertainty on velocity dispersionkm/sstat.errorintnullable