J/ApJS/244/7ivo://CDS.VizieR/J/ApJS/244/7doi:10.26093/cds/vizier.22440007CDSJameson K.E.McClure-Griffiths N.M.Liu B.Dickey J.M.,Staveley-Smith L.Stanimirovic S.Dempsey J.Dawson J.R.Denes H.,Bolatto A.D.Li DiWong T.2020-08-21T08:26:52Z2020-03-05T08:33:24ZCDS support team

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

cds-question@unistra.frmagellanic-cloudsh-i-line-emissionradio-astronomyinterstellar-mediumWe present the first results from the Small Magellanic Cloud portion of a new Australia Telescope Compact Array HI absorption survey of both of the Magellanic Clouds, comprising over 800hr of observations. Our new HI absorption line data allow us to measure the temperature and fraction of cold neutral gas in a low-metallicity environment. We observed 22 separate fields, targeting a total of 55 continuum sources, against 37 of which we detected HI absorption; from this we measure a column-density-weighted mean average spin temperature of <Ts>=150K. Splitting the spectra into individual absorption line features, we estimate the temperatures of different gas components and find an average cold gas temperature of ~30K for this sample, lower than the average of ~40K in the Milky Way. The HI appears to be evenly distributed throughout the SMC, and we detect absorption in 67% of the lines of sight in our sample, including some outside the main body of the galaxy (N_HI_>2x10^21^cm^-2^). The optical depth and temperature of the cold neutral atomic gas show no strong trend with location spatially or in velocity. Despite the low-metallicity environment, we find an average cold gas fraction of ~20%, not dissimilar from that of the Milky Way.2019ApJS..244....7Jhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/244/7CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJS/145/329 : Millennium Arecibo 21-cm Survey (Heiles+, 2003)J/MNRAS/355/44 : ATCA SMC Radio Continuum Source. II. (Payne+, 2004)J/ApJ/793/132 : Perseus cloud sources Gaussian param. (Stanimirovic+, 2014)J/MNRAS/490/1202 : ASKAP EMU ESP, SMC Radio Continuum Survey (Joseph+ 2020)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJS/244/7https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJS/244/7http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJS/244/7https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJS/244/7https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJS/244/7http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJS/244/7GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJS/244/7/table1 (Absorption spectra quantities of the continuum sources in the SMC)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/244/7/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/244/7/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/244/7/table1?GETtext/xml+votable180.050000true7.2771-73.89250.0055555555555555565/8323 6/33297 33298 33299 33304 33306 33313 33316 33317 33324 33328 33329 33330https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJS/244/7?format=asciiRadiodefaultJ/ApJS/244/7/table1Absorption spectra quantities of the continuum sources in the SMCl_TsLimit flag on Tsmeta.code.errorcharTs[17/806] Weighted mean average spin temperatureKphys.temperature;stat.meanfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFieldField identifier (HHMM+DDMM)meta.id;obs.fieldcharNameSource name (HHMMSS-DDMMSS; J2000)meta.id;meta.maincharRAJ2000[7.2/23.2] Right Ascension (J2000)degpos.eq.ra;meta.mainDEJ2000[-74.4/-71] Declination (J2000)degpos.eq.dec;meta.mainScont[16/553] Continuum source fluxmJyphot.flux.density;em.radio.750-1500MHzfloattauPk[0.04/9.4] Peak optical depth (1)phys.absorption.opticalDepth;stat.maxfloate_tauPk[0.01/1.3] 1{sigma} uncertainty on the optical depth (1)stat.errorfloatEW[-25.6/55.4] Absorption equivalent width (2)km/sspect.line.eqWidthfloate_EW[0.1/7.4] Uncertainty in EWkm/sstat.error;spect.line.eqWidthfloatNHI[0.4/9.1] HI column density (3)1e+21cm**-2phys.columnDensity;em.radio.750-1500MHzfloate_NHI[0.1/0.6] Uncertainty in NHI1e+21cm**-2stat.errorfloatfHI[1.0/1.53] HI correction factor to the column density for the isothermal casearith.factorfloate_Ts[4/267]? Uncertainty in <Ts>Kstat.errorfloatnullable