J/MNRAS/435/1198ivo://CDS.VizieR/J/MNRAS/435/1198doi:10.26093/cds/vizier.74351198CDSD'Odorico V.Cupani G.Cristiani S.Maiolino R.Molaro P.Nonino M.,Centurion M.Cimatti A.Di Serego Alighieri S.Fiore F.Fontana A.,Gallerani S.Giallongo E.Mannucci F.Marconi A.Pentericci L.,Viel M.Vladilo G.2024-08-06T20:16:50Z2015-03-05T07:52:23ZCDS support team

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

cds-question@unistra.frquasarsspectroscopyWe present the results of observations taken with the X-shooter spectrograph devoted to the study of quasars at z~6. This paper focuses on the properties of metals at high redshift traced, in particular, by the CIV doublet absorption systems. Six objects were observed with resolutions =~27 and 34km/s in the visual, and 37.5 and 53.5km/s in the near-infrared. We detected 10^2^ CIV lines in the range: 4.35<z<6.2 of which 27 are above z~5. Thanks to the characteristics of resolution and spectral coverage of X-shooter, we could also detect 25 SiIV doublets associated with the CIV at z>~5. The column density distribution function of the CIV line sample is observed to evolve in redshift for z>~5.3, with respect to the normalization defined by low-redshift (1.5<z<4) CIV lines. This behaviour is reflected in the redshift evolution of the CIV cosmic mass density, {Omega}_CIV_, of lines with column density in the range 13.4<logN(CIV)<15, which is consistent with a drop of a factor of ~2 for z>~5.3. Considering only the stronger CIV lines (13.8<logN(CIV)<15), {Omega}_CIV_ gently rises by a factor of ~10 between z=~6.2 and z=~1.5 with a possible flattening towards z~0. The increase is well fitted by a power law: {Omega}_CIV=(2+/-1)x10^-8^[(1+z)/4]^-3.1+/-0.1^. An insight into the properties of the CIV absorbers and their evolution with redshift is obtained by comparing the observed column densities of associated CIV, SiIV and CII absorptions with the output of a set of cloudy photoionization models. As already claimed by cosmological simulations, we find that CIV is a good tracer of the metallicity in the low-density intergalactic medium (IGM) gas at z~5-6 while at z~3 it arises in gas with overdensity {delta}~100.2013MNRAS.435.1198Dhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/435/1198CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/435/1198https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/435/1198http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/435/1198https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/435/1198https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/435/1198http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/435/1198GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/435/1198/table1 (X-shooter spectroscopic observations)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/435/1198/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/435/1198/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/435/1198/table1?GETtext/xml+votable180.050000true124.614166717.38111110.0055555555555555566/4662 21872 26239 26524 27440 44463https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/435/1198?format=asciiOpticaldefaultJ/MNRAS/435/1198/table1X-shooter spectroscopic observationsQSOQuasar namemeta.id;meta.maincharprimaryrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintzem[5.8/6.4] Redshift of emission linessrc.redshiftfloatJmag[17/19] J-band (near-IR) magnitudemagphot.mag;em.IR.JfloatTvisExposure time in visible (optical)stime.duration;obs.exposureintTnirExposure time in near-infraredstime.duration;obs.exposureintSNRv[50/125] Signal-to-noise ratio at 0.9{mu}mstat.snrintSNRi[7/24] Signal-to-noise ratio at 1.035{mu}mstat.snrintNsysNumber of absoption systems detected for this quasarmeta.numberintnullablezC.minLower value of CIV absoption redshiftinstr.bandwidthfloatzC.maxUpper value of CIV absoption redshiftinstr.bandwidthfloatDXCIV redshift absorption path {Delta}X_CIV_src.redshift;arith.difffloatzSi.minLower value of SiIV absoption redshiftinstr.bandwidthfloatzSi.maxUpper value of SiIV absoption redshiftinstr.bandwidthfloatSimbadSimbad column added by the CDSmeta.ref.urlchar_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.mainJ/MNRAS/435/1198/abs_systAbsorption systems detected (tables A1--A6)Sys[1/22] System number (in QSO)meta.idintQSOQuasar namemeta.id.parentcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintm_Sys[abcdefghi] Multiplicity index on Systemmeta.code.multipcharIonIon (CII, CIV, or SiIV)phys.atmol.ionStagecharn_Ion[asbmlS ] Note on line (1)meta.notecharz[4.4/6.0]? Redshiftsrc.redshiftdoublenullablee_z? rms uncertainty on zstat.error;src.redshiftdoublenullablel_W0Limit flag on W0meta.code.errorcharW0[0/1.6]? Rest-frame equivalent width ({AA})0.1nmspect.line.eqWidthfloatnullablee_W0? rms uncertainty on W00.1nmstat.errorfloatnullableb[7/94]? Doppler velocity widthkm/sspect.line.widthfloatnullablee_b? rms uncertainty on bkm/sstat.errorfloatnullablel_logNLimit flag on logNmeta.code.errorcharlogN[12/14.6]? Abundance (column density)log(cm**-2)phys.abundfloatnullablee_logN? rms uncertainty on logNlog(cm**-2)stat.errorfloatnullable