J/A+A/643/A6ivo://CDS.VizieR/J/A+A/643/A6doi:10.26093/cds/vizier.36430006CDSCassata P.Morselli L.Faisst A.Ginolfi M.Bethermin M.Capak P.,Le Fevre O.Schaerer D.Silverman J.Yan L.Lemaux B.C.Romano M.,Talia M.Bardelli S.Boquien M.Cimatti A.Dessauges-Zavadsky M.,Fudamoto Y.Fujimoto S.Giavalisco M.Hathi N.P.Ibar E.Jones G.,Koekemoer A.M.Mendez-Hernandez H.Mancini C.Oesch P.A.Pozzi F.,Riechers D.A.Rodighiero G.Vergani D.Zamorani G.Zucca E.2022-04-07T08:21:21Z2021-02-10T14:10:20ZCDS support team

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

cds-question@unistra.frsurveysinterstellar-mediumgalaxiescatalogsredshiftedmillimeter-astronomysubmillimeter-astronomyinfrared-astronomyThe Lyman-{alpha} line in the ultraviolet (UV) and the [CII] line in the far-infrared (FIR) are widely used tools to identify galaxies in the early Universe and to obtain insights into interstellar medium (ISM) properties in high-redshift galaxies. By combining data obtained with ALMA in band 7 at ~320GHz as part of the ALMA Large Program to INvestigate [CII] at Early Times (ALPINE) with spectroscopic data from DEIMOS at the Keck Observatory, VIMOS and FORS2 at the Very Large Telescope, we assembled a unique sample of 53 main-sequence star-forming galaxies at 4.4<z<6 in which we detect both the Lyman-{alpha} line in the UV and the [CII] line in the FIR. The goal of this paper is to constrain the properties of the Ly{alpha} emission in these galaxies in relation to other properties of the ISM. We used [CII], observed with ALMA, as a tracer of the systemic velocity of the galaxies, and we exploited the available optical spectroscopy to obtain the Ly{alpha}-[CII] and ISM-[CII] velocity offsets. We find that 90% of the selected objects have Ly{alpha}-[CII] velocity offsets in the range 0<{Delta}v_Ly{alpha}-[CII]_<400km/s, in line with the few measurements available so far in the early Universe, and significantly smaller than those observed at lower redshifts. At the same time, we observe ISM-[CII] offsets in the range -500<{Delta}v_ISM-[CII]_<0km/s, in line with values at all redshifts, which we interpret as evidence for outflows in these galaxies. We find significant anticorrelations between {Delta}v_Ly{alpha}-[CII]_ and the Ly{alpha} rest-frame equivalent width EW_0_(Ly{alpha}) (or equivalently, the Ly{alpha} escape fraction f_esc_(Ly{alpha})): galaxies that show smaller {Delta}v_Ly{alpha}-[CII]_ have larger EW_0_(Ly{alpha}) and f_esc_(Ly{alpha}). We interpret these results in the framework of available models for the radiative transfer of Ly{alpha} photons. According to the models, the escape of Ly{alpha} photons would be favored in galaxies with high outflow velocities, producing large EW_0_(Ly{alpha}) and small {Delta}v_Ly{alpha}-[CII]_, in agreement with our observations. The uniform shell model would also predict that the Ly{alpha} escape in galaxies with slow outflows (0<v_out_<300km/s) is mainly determined by the neutral hydrogen column density (NHI) along the line of sight, while the alternative model by Steidel et al. (2010ApJ...717..289S) would more highly favor a combination of NHI at the systemic velocity and covering fraction as driver of the Ly{alpha} escape. We suggest that the increase in Ly{alpha} escape that is observed in the literature between z~2 and z~6 is not due to a higher incidence of fast outflows at high redshift, but rather to a decrease in average NHI along the line of sight, or alternatively, a decrease in HI covering fraction.2020A&A...643A...6Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/643/A6CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/643/A2 : ALPINE DR1 merged catalog (Bethermin+, 2020)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/643/A6https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/643/A6http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/643/A6https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/643/A6https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/643/A6http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/643/A6GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/643/A6/tableb (Properties from multiwavelength photometry (table B1) and Ly{alpha}, [CII], and ISM measurements (table B2) for the sample)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/643/A6/tableb?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/643/A6/tableb?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/643/A6/tableb?GETtext/xml+votable180.050000true53.2251-27.833560.0055555555555555566/27256 27258-27259 35935https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/643/A6?format=asciiInfraredMillimeterdefaultJ/A+A/643/A6/tablebProperties from multiwavelength photometry (table B1) and Ly{alpha}, [CII], and ISM measurements (table B2) for the sampleSimbadNameSimbad column added by the CDSmeta.idcharnullableIDName (G1)meta.idcharfesc(Lya)Ly{alpha} escape fractionstat.fit.paramfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlog(M)Masslog(solMass)phys.massfloatE_log(M)Error on Mass (upper value)log(solMass)stat.error;stat.maxfloate_log(M)Error on Mass (lower value)log(solMass)stat.errorfloatlogSFRStar formation ratelog(solMass.yr**-1)phys.SFRfloatE_logSFRError on logSFR (upper value)log(solMass.yr**-1)stat.error;stat.maxfloate_logSFRError on logSFR (lower value)log(solMass.yr**-1)stat.error;phys.SFRfloatE(B-V)Extinctionmagphot.color.excessfloatMFUVAbsolute FUV magnitudemagphys.magAbsfloatE_MFUVError on MFUV (upper value)magstat.error;stat.maxfloate_MFUVError on MFUV (lower value)magstat.errorfloatNameName as in ALPINE DR1 catalog (Cat. J/A+A/643/A2)meta.id;meta.maincharS/N([CII])Signal-to-noise from [CII]stat.snrfloatEW0(Lya)Ly{alpha} equivalent width0.1nmspect.line.eqWidthfloate_EW0(Lya)rms uncertainty on EW0(Lya)0.1nmstat.errorfloatE_fesc(Lya)Error on fesc(Lya) (upper value)stat.error;stat.maxfloate_fesc(Lya)Error on fesc(Lya) (lower value)stat.errorfloatz[CII]Redshift from [CII] linesrc.redshift;pos.heliocentricfloate_z[CII]rms uncertainty on z[CII]stat.error;src.redshiftfloatDLyaLy{alpha} velocity offsetkm/sspect.dopplerVelocinte_DLyarms uncertainty on DLyakm/sstat.errorintDISM? ISM velocity offsetkm/sphys.velocintnullableE_DISM? Error on ISM (upper value)km/sstat.error;stat.maxintnullablee_DISM? Error on ISM (lower value)km/sstat.errorintnullable_RARight Ascension (J2000) from J/A+A/643/A2/catalogdegpos.eq.ra;meta.main_DEDeclination (J2000) from J/A+A/643/A2/catalogdegpos.eq.dec;meta.main