J/ApJ/775/78ivo://CDS.VizieR/J/ApJ/775/78doi:10.26093/cds/vizier.17750078CDSFumagalli M.O'Meara J.M.Prochaska J.X.Worseck G.2017-07-03T14:26:52Z2015-04-14T08:18:32ZCDS support team

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

cds-question@unistra.frquasarsredshiftedspectroscopyWe present the results of a blind survey of Lyman limit systems (LLSs) detected in absorption against 105 quasars at z~3 using the blue sensitive MagE spectrograph at the Magellan Clay telescope. By searching for Lyman limit absorption in the wavelength range {lambda}~3000-4000{AA}, we measure the number of LLSs per unit redshift {ell}(z)=1.21+/-0.28 at z~2.8. Using a stacking analysis, we further estimate the mean free path of ionizing photons in the z~3 universe {lambda}_mfp_^912^=100+/-29h_70.4_^-1^Mpc. Combined with our LLS survey, we conclude that systems with logN_HI_>=17.5/cm2 contribute only ~40% to the observed mean free path at these redshifts. Furthermore, with the aid of photoionization modeling, we infer that a population of ionized and metal poor systems is likely required to reproduce the metal line strengths observed in a composite spectrum of 20 LLSs with log N_HI_~17.5-19/cm2 at z~2.6-3.0. Finally, with a simple toy model, we deduce that gas in the halos of galaxies can alone account for the totality of LLSs at z<~3, but a progressively higher contribution from the intergalactic medium is required beyond z~3.5. We also show how the weakly evolving number of LLSs per unit redshift at z<~3 can be modeled either by requiring that the spatial extent of the circumgalactic medium is redshift invariant in the last ~10Gyr of cosmic evolution or by postulating that LLSs arise in halos that are rare fluctuations in the density field at each redshift.2013ApJ...775...78Fhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/775/78CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toVII/270 : SDSS quasar catalog: tenth data release (Paris+, 2014)VII/260 : The SDSS-DR7 quasar catalog (Schneider+, 2010)J/MNRAS/435/482 : DLA system from SDSS DR5 (Jorgenson+, 2013)J/ApJ/770/138 : Metallicities of Lyman limit systems and DLA (Lehner+, 2013)J/ApJ/765/137 : HST survey for Lyman limit systems. II. (O'Meara+, 2013)J/ApJ/762/L19 : Quasar pairs spectroscopy (Prochaska+, 2013)J/ApJ/755/89 : Metallicities of damped Ly{alpha} systems (Rafelski+, 2012)J/ApJ/740/91 : Ly{alpha} & OVI in galaxies around quasars (Prochaska+, 2011)J/ApJ/736/42 : HST QSO Catalog (Ribaudo+, 2011)J/A+A/530/A50 : Principal Component Analysis of QSO UV spectra (Paris+, 2011)J/ApJ/728/23 : GALEX UV-bright high-redshift quasars (Worseck+, 2011)J/ApJ/724/L176 : MgII absorbing gas around galaxies (Chen+, 2010)J/ApJ/718/392 : SDSS Lyman limit systems at z~3.5 (Prochaska+, 2010)J/ApJ/648/L97 : SDSS QSOs supersolar super-LLS (Prochaska+ 2006)J/MNRAS/354/L31 : SDSS DR2 QSO and DLA properties (Murphy+, 2004)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/775/78https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/775/78http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/775/78https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/775/78https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/775/78http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/775/78GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/775/78/qsos (Log of MagE spectroscopic observations and results of the {tau}>=2 Lyman limit system (LLS) survey)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/775/78/qsos?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/775/78/qsos?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/775/78/qsos?GETtext/xml+votable180.050000true0.58795830.36369440.0055555555555555566/4099 4125 4149 4280 4301 4378 8192 8289 8291 8300 8376 8393 8521 8522 8714 16652 16752 17149 17299 17317 17510 17511 17518 17556 17813 17898 17917 18069 18083 18090 18537 18582 18738 18769 18785 18800 18858 19028 19056 19060 19099 19185 19387 22594 23190 23210 25441 25995 26092 26280 27237 27289 27364 27365 27429 27537 27550 27608 27868 27889 27913 28039 30031 31375 31451 31534 31622 31638 31656 31730 33632 33994 34252 34379 34433 34501 34514 34635 34696 35277 35522 35585 35752 35880 35993 36810 38477 38775 39100 40219 40446 43920 44780 46208 46577 46728 46735 46793 47154 48619 49100 49121 49124https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/775/78?format=asciiOpticaldefaultJ/ApJ/775/78/qsosLog of MagE spectroscopic observations and results of the {tau}>=2 Lyman limit system (LLS) surveySimbadNameSimbad column added by the CDSmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameQSO designationmeta.id;meta.maincharn_NameRemark on quasar (G1)meta.notecharRAJ2000Hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of declination (J2000)pos.eq.dec;meta.mainzqso[2.7/3.4] QSO redshiftsrc.redshift;pos.heliocentricfloate_zqso[0.006/0.02] Statistical error on the quasar redshift from broad emission linesstat.errorfloate_Vel[521/792] Corresponding error on the quasar redshift in velocitykm/sstat.errorintDateDate(s) of observation (YYMMDD)time.epochcharExp[600/5700] Exposure timestime.duration;obs.exposureintSlit[0.7] Slitarcsecinstr.setupfloatS/N[6.2/56.7] S/N at 5500{AA}stat.snrfloatSDSSCross-match within 2" with the SDSS-DR7 quasar (VII/260) and photometric (II/294) catalogsmeta.ref.urlintnullableSloanDisplay the SDSS data for the nearest objectmeta.ref.urlcharNEDSimbad column added by the CDSmeta.ref.urlcharSrc? Reference (1)meta.ref;pos.frameintnullablezstart[2.6/3.4] z_start_ (2)src.redshift;pos.heliocentricfloatzend[2.4/3.3] z_end_ (2)src.redshift;pos.heliocentricfloatzlls[0/3.3] LLS redshift (2)src.redshift;pos.heliocentricfloat