J/A+A/633/A14ivo://CDS.VizieR/J/A+A/633/A14doi:10.26093/cds/vizier.36330014CDSRiener M.Kainulainen J.Beuther H.Henshaw J.D.Orkisz J.H.Wang Y.2019-12-27T03:31:01Z2019-12-27T04:27:33ZCDS support team

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

cds-question@unistra.frsurveysgalaxy-planesmilky-way-galaxyradio-spectroscopyradio-astronomyinterstellar-mediumgalaxy-kinematicsThe analysis of large molecular line surveys of the Galactic plane is essential for our understanding of the gas kinematics on Galactic scales and, in particular, its link with the formation and evolution of dense structures in the interstellar medium. An approximation of the emission peaks with Gaussian functions allows for an efficient and straightforward extraction of useful physical information contained in the shape and Doppler-shifted frequency of the emission lines contained in these enormous data sets. In this work, we present an overview and the first results of a Gaussian decomposition of the entire Galactic Ring Survey (GRS) ^13^CO (1-0) data that consists of about 2.3 million spectra. We performed the decomposition with the fully automated GaussPy+ algorithm and fitted about 4.6 million Gaussian components to the GRS spectra. These decomposition results enable novel and unexplored ways to interpret and study the gas velocity structure. We discuss the statistics of the fit components and relations between the fitted intensities, velocity centroids, and velocity dispersions. We find that the magnitude of the velocity dispersion values increase towards the inner Galaxy and around the Galactic midplane, which we speculate is partly due to the influence of the Galactic bar and regions with higher non-thermal motions located in the midplane, respectively. We also used our decomposition results to infer global properties of the gas emission and find that the number of fit components used per spectrum is indicative of the amount of structure along the line of sight. We find that the emission lines from regions located on the far side of the Galaxy show increased velocity dispersion values, which are likely due to beam averaging effects. We demonstrate how this trend has the potential to aid in characterising Galactic structure by disentangling emission that belongs to the nearby Aquila Rift molecular cloud from emission that is more likely associated with the Perseus and Outer spiral arms. With this work, we also make our entire decomposition results available.2020A&A...633A..14Rhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/633/A14CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-tohttps://www.bu.edu/galacticring/new_data.html : GRS survey Home Pagehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/633/A14https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/633/A14http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/633/A14https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/633/A14https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/633/A14http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/633/A14GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/633/A14/table1 (Decomposition results)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/633/A14/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/633/A14/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/633/A14/table1?GETtext/xml+votable180.050000true294.3538119.016420.0055555555555555565/3242 7376-7377 7380 7382-7383 7554 7561 7564-7565 7567 7578-7579 7604-7605 7648 7650-7651 7654 7661 7672-7673 7678-7679 6/14336-14337 29114-29115 29118-29119 29162-29163 29166 29456-29457 29460-29461 29513 29516-29517 29526-29527 29556-29557 30220 30222-30223 30234 30240-30241 30243 30253 30264-30265 30306-30307 30310 30328 30330-30331 30334-30335 30400-30401 30404-30405 30407 30428-30429 30598-30599 30610 30620 30622-30623 30629 30640-30641 30666-30667 30696-30697 30700-30701 30703-30704 30706-30707 30710-30711 32084-32085https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/633/A14?format=asciiMillimeterRadiodefaultJ/A+A/633/A14/table1Decomposition resultsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintXpos[0/6829] Pixel position in Galactic longitudepixpos.galactic.lon;instr.pixelintYpos[0/357] Pixel position in Galactic latitudepixpos.galactic.lat;instr.pixelintGLON[14.002/56.0] Galactic longitude positiondegpos.galactic.lonindexedGLAT[-1.1/1.096] Galactic latitude positiondegpos.galactic.latindexedTB[0.08/25.57] Fitted peak main beam brightness temperature valueKphys.temperature;meta.main;stat.maxfloate_TB[0.0/14.62]? Uncertainty in TB (1)Kstat.errorfloatnullableVLSR[-4.95/134.89] Fitted centroid velocity valuekm/sphys.veloc;pos.lsrfloate_VLSR[0.0/10.0]? Uncertainty in VLSR (1)km/sstat.error;phys.veloc;pos.lsrfloatnullablesigma[0.09/49.12] Fitted velocity dispersion valuekm/sphys.veloc.dispersion;meta.modelleddoublee_sigma[0.0/15.93]? Uncertainty in sigma (1)km/sstat.errorfloatnullablerms[0.04/1.56] Root-mean-square noise value of spectrumKstat.snr;instr.det.noisefloatpvalue[0.0/99.0] p-value of normality test for normally distributed residual values%stat.fit.goodnessfloataiccValue of corrected Akaike information criterionstat.fit.paramfloatrchi2Value of reduced chi-squaredstat.fit.chi2floatNcomp[1/23] Number of Gaussian fit componentsmeta.numberintNmed[0/15] Weighted median number of fit components determined from neighbouring fit solutionsmeta.numberintNjump[0/8] Number of component jumps (>2) towards directly neighbouring fit solutionsmeta.numberintF1[0/1] Strongly blended with another fit componentmeta.codeintF2[0/1] Negative residual feature introduced by fit componentmeta.codeintF3[0/1] Comparatively broad fit componentmeta.codeintF4[0/7] Centroid velocity of fit component not compatible with neighboring fit solutionsmeta.codeint_RA.icrsRight ascension (ICRS) (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services)degpos.eq.ranullableindexed_DE.icrsDeclination (ICRS) (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services)degpos.eq.decnullableindexed