J/ApJS/238/14ivo://CDS.VizieR/J/ApJS/238/14doi:10.26093/cds/vizier.22380014CDSMurray C.E.Stanimirovic S.Goss W.M.Heiles C.Dickey J.M.Babler B.,Kim C.-G.2022-06-13T11:23:43Z2022-05-30T08:43:31ZCDS support team

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

cds-question@unistra.frradio-astronomyh-i-line-emissioninterstellar-mediumsurveysactive-galactic-nucleiWe present 21cm Spectral Line Observations of Neutral Gas with the VLA (21-SPONGE), a Karl G. Jansky Very Large Array (VLA) large project (~600hr) for measuring the physical properties of Galactic neutral hydrogen (HI). 21-SPONGE is distinguished among previous Galactic HI studies as a result of (1) its exceptional optical depth sensitivity ({sigma}_{tau}_<10^-3^ per 0.42km/s channel over 57 lines of sight), (2) matching 21cm emission spectra with the highest possible angular resolution (~4') from the Arecibo Observatory, and (3) detailed comparisons with numerical simulations for assessing observational biases. We autonomously decompose 21cm spectra and derive the physical properties (i.e., spin temperature, T_s_, and column density) of the cold neutral medium (CNM; T_s_<250K), thermally unstable medium (UNM; 250K<T_s_<1000K), and warm neutral medium (WNM; T_s_>1000K) simultaneously. Of the total HI mass observed, 50% is detected in both absorption and emission. The CNM makes up the majority of the absorbing gas (56%+/-10%) and 28% of the total HI mass including gas detected only in emission. We find that 20% of the total HI mass is thermally unstable (41%+/-10% of HI detected in absorption), with no significant variation with Galactic latitude. Finally, although the WNM makes up 52% of the total HI mass, we detect little evidence for WNM absorption with 1000K<T_s_<4000K. Following spectral modeling, we detect a stacked residual absorption feature corresponding to WNM with T_s_~10^4^K. We conclude that excitation in excess of collisions likely produces significantly higher WNM T_s_ than predicted by steady-state models.2018ApJS..238...14Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/238/14CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toVIII/54 : Atlas of Galactic Neutral Hydrogen (Hartmann+, 1997)VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)VIII/76 : Leiden/Argentine/Bonn (LAB) Survey of Galactic HI (Kalberla+ 2005)J/ApJS/145/329 : Millennium Arecibo 21-cm Survey (Heiles+, 2003)J/ApJ/793/132 : Perseus cloud sources Gaussian param. (Stanimirovic+, 2014)J/A+A/585/A41 : EBHIS spectra and HI column density maps (Winkel+, 2016)J/ApJS/234/2 : The GALFA-HI survey data release 2 (Peek+, 2018)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJS/238/14https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJS/238/14http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJS/238/14https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJS/238/14https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJS/238/14http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJS/238/14GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJS/238/14/sponge (21-SPONGE VLA information (Table 1) and column densities (Table 2))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/238/14/sponge?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/238/14/sponge?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/238/14/sponge?GETtext/xml+votable180.050000true5.6058330.2489440.0055555555555555566/18 392 556 1129 1263 1521 2245 2249 4366 5311 8264 9347 9442 9633 10288 10432 10440 13007 13120 13224 13287 14359 14539 14644 18096 18895 19101 19177 19398 19543 20099 22375 23167 23323 24116 24165 24185 24247 24300 24349 26100 26292 26491 27060 27514 27532 28279 31346 31423 31509 32000 32394https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJS/238/14?format=asciiRadiodefaultJ/ApJS/238/14/sponge21-SPONGE VLA information (Table 1) and column densities (Table 2)SimbadNameSimbad column added by the CDSmeta.idcharnullablefCNM[0/0.7]? Cold Neutral Medium (CNM) fraction per LOS (f_CNM_=N(HI)_CNM_/N(HI)_total_)phys.columnDensity;arith.difffloatnullablee_fCNM[0.02/0.5] fCNM uncertaintystat.errorfloatnullablefUNM[0/0.77]? Thermally unstable medium (UNM) fraction per LOS (f_UNM_=N(HI)_UNM_/N(HI)_total_)phys.columnDensity;arith.difffloatnullablee_fUNM[0.04/1] fUNM uncertaintystat.errorfloatnullableNEDNED column added by the CDSmeta.ref.urlcharnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNVSSDisplay data from NVSS (VIII/65) within 30"meta.ref.urlintnullableNameName of the radio sourcemeta.id;meta.maincharRejReason for the 5 rejected source (1)meta.notecharRAJ2000Hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of declination (J2000)pos.eq.dec;meta.mainGLON[7/353] Galactic longitudedegpos.galactic.lonGLAT[-62/81.1] Galactic latitudedegpos.galactic.latfloatS1.4GHz[2.8/55] NVSS flux density at 1.4GHzphot.flux.density;em.radio.750-1500MHzfloatBeam1[0.1/20.3]? Synthesized beamarcsecphys.angSizefloatnullableBeam2[0/13.7]? Synthesized beamarcsecphys.angSizefloatnullableerrTau[0.4/6.9]? rms uncertainty in optical depth (2)stat.error;phys.absorption.opticalDepthfloatnullableTauPk[0.003/3.6]? Peak optical depth, {tau}_peak_phys.absorption.opticalDepth;stat.maxfloatnullablee_TauPk[0.001/0.01]? TauPk uncertaintystat.errorfloatnullableTaudv[0.001/17.8]? Integrated optical depth (3)km/sphys.absorption.opticalDepthfloatnullablee_Taudv[0.002/0.03]? dv uncertaintykm/sstat.errorfloatnullableNfNumber of fit parameters for this source (link to Table 5)meta.numberintnullableNHIthin[0.71/38.53] Optically thin HI column density; see Equation 71e+20cm**-2phys.columnDensityfloatnullablee_NHIthin[0.02/2.81] NHIthin uncertainty1e+20cm**-2stat.errorfloatnullableNHIiso[0.7/54.1] Isothermal HI column density; see Equation 81e+20cm**-2phys.columnDensityfloatnullablee_NHIiso[0.03/4] NHIiso uncertainty1e+20cm**-2stat.errorfloatnullableNHItot[0.71/53.13] Total HI column density (4)1e+20cm**-2phys.columnDensityfloatnullablee_NHItot[0/18.06] NHItot uncertainty1e+20cm**-2stat.errorfloatnullableNHICNM[0/24.46] Sum of N(HI)_abs_ in the CNM (Ts<=250K) (5)1e+20cm**-2phys.columnDensityfloatnullableNHIUNM[0/26.6] Sum of N(HI)_abs_ in the UNM (250<Ts>=1000K) (5)1e+20cm**-2phys.columnDensityfloatnullableJ/ApJS/238/14/table5Fitted parametersrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameName of the radio sourcemeta.id;meta.mainchartau0[0.001/2.8]? Amplitude (1)phys.absorption.opticalDepthfloatnullablee_tau0[0.001/20000]? tau0 uncertaintystat.errordoublenullableDelnu0[0.1/37.4]? Mean velocity (1)km/sphys.veloc;stat.meanfloatnullablee_Delnu0[0.1/10000]? Delnu0 uncertaintykm/sstat.errorfloatnullablenu0[-69/46.1]? FWHM (1)km/sspect.line.widthfloatnullablee_nu0[0.1/900]? nu0 uncertaintykm/sstat.errorfloatnullableTBn[0.1/87.5]? Fit parameter, T_B,n_ (2)Kstat.fit.param;meta.modelledfloatnullablee_TBn[0/16.7]? TBn uncertaintyKstat.errorfloatnullableDelnu0n[0.6/33.7]? Fit parameter, {Delta}{nu}_0,n_ (2)km/sstat.paramfloatnullablee_Delnu0n[0.1/0.4]? Delnu0n uncertaintykm/sstat.errorfloatnullablenu0n[-65.4/42.1]? Fit parameter, {nu}_0,n_ (2)km/sstat.paramfloatnullablee_nu0n[0.1/0.3]? nu0n uncertaintykm/sstat.errorfloatnullableTs[10/2613]? Average spin temperature (3)Kphys.temperatureintnullablee_Ts[0/403]? Ts uncertaintyKstat.errorintnullableNHI[0/25.55]? Column density computed from fitted parameters (Equation (6))1e+20cm**-2phys.columnDensity;meta.modelledfloatnullablee_NHI[0/9.16]? NHI uncertainty1e+20cm**-2stat.errorfloatnullableO[1/13]? Order of components along the line of sight (LOS) (4)meta.numberintnullablef[0/1]? Fraction of the warm neutral medium (WNM) (5)stat.fit.paramfloatnullable