J/A+A/641/A53ivo://CDS.VizieR/J/A+A/641/A53doi:10.26093/cds/vizier.36410053CDSWang Y.Beuther H.Schneider N.Meidt S.E.Linz H.Ragan S.,Zucker C.Battersby C.Soler J.D.Schinnerer E.Bigiel F.Colombo D.,Henning T.2022-03-07T07:18:57Z2020-09-08T08:02:14ZCDS support team

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

cds-question@unistra.frinterstellar-mediummolecular-cloudsradio-astronomyRecent surveys of the Galactic plane in the dust continuum and CO emission lines reveal that large (>~50pc) and massive (>~10^5^M_{sun}_) filaments, know as giant molecular filaments (GMFs), may be linked to galactic dynamics and trace the mid-plane of the gravitational potential in the Milky Way. Yet our physical understanding of GMFs is still poor. We investigate the dense gas properties of one GMF, with the ultimate goal of connecting these dense gas tracers with star formation processes in the GMF. We have imaged one entire GMF located at l~52-54{deg} longitude, GMF54 (~68pc long), in the empirical dense gas tracers using the HCN(1-0), HNC(1-0), HCO^+^(1-0) lines, and their ^13^C isotopologue transitions, as well as the N_2_H^+^1-0) line. We study the dense gas distribution, the column density probability density functions (N-PDFs) and the line ratios within the GMF. The dense gas molecular transitions follow the extended structure of the filament with area filling factors between 0.06 and 0.28 with respect to ^13^CO(1-0). We constructed the N-PDFs of H_2_ for each of the dense gas tracers based on their column densities and assumed uniform abundance. The N-PDFs of the dense gas tracers appear curved in log-log representation, and the HCO^+^ NPDF has the largest log-normal width and flattest power-law slope index. Studying the N-PDFs for sub-regions of GMF54, we found an evolutionary trend in the N-PDFs that high-mass star forming and Photon Dominated Regions (PDRs) have flatter power-law indices. The integrated intensity ratios of the molecular lines in GMF54 are comparable to those in nearby galaxies. In particular, the N_2_H^+^/^13^CO ratio, which traces the dense gas fraction, has similar values in GMF54 and all nearby galaxies except Ultraluminous Infrared Galaxies (ULIRGs). As the largest coherent cold gaseous structure in our Milky Way, GMFs, are outstanding candidates for connecting studies of star formation on Galactic and extragalactic scales. By analyzing a complete map of the dense gas in a GMF we have found that: (1) the dense gas N-PDFs appear flatter in more evolved regions and steeper in younger regions, and (2) its integrated dense gas intensity ratios are similar to those of nearby galaxies.2020A&A...641A..53Whttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/641/A53CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/634/A139 : Giant Molecular Filament THOR datacubes (Wang+, 2020)J/A+A/638/A44 : Infrared dark cloud G28.3 HI and CI maps (Beuther+, 2020)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/641/A53https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/641/A53http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/641/A53https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/641/A53https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/641/A53http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/641/A53GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/641/A53/list (List of fits images and datacubes)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/641/A53/list?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/641/A53/list?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/641/A53/list?GETtext/xml+votable180.050000true292.471206618.04446710.0055555555555555566/30716https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/641/A53?format=asciiRadiodefaultJ/A+A/641/A53/listList of fits images and datacubesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGLONGalactic longitude of center (J2000)degpos.galactic.lonGLATGalactic latitude center (J2000)degpos.galactic.latNxNumber of pixels along X-axismeta.numberintNyNumber of pixels along Y-axismeta.numberintNz? Number of slices for the datacubesmeta.numberintnullablebVRAD? Lower value of VRAD velocity for the datacubesm/sphys.veloc;pos.heliocentricintnullableBVRAD? Upper value of VRAD velocity for the datacubesm/sphys.veloc;pos.heliocentricintnullabledVRAD? VRAD resolution for the datacubesm/sspect.resolutionintnullablesizeSize of FITS fileKibytephys.size;meta.fitsintFileNameName of FITS file, in subdirectory fitsmeta.id;meta.fitscharTitleTitle of the FITS filemeta.title;meta.fits_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