J/A+A/604/A65ivo://CDS.VizieR/J/A+A/604/A65doi:10.26093/cds/vizier.36040065CDSAbreu-Vicente J.Stutz A.Henning T.Keto E.Ballesteros-Paredes J.,Robitaille T.2017-09-04T13:45:30Z2017-08-07T08:31:54ZCDS support team

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

cds-question@unistra.frinterstellar-mediummillimeter-astronomyphotometrysubmillimeter-astronomyHerschel has revolutionized our ability to measure column densities (N_H_) and temperatures (T) of molecular clouds thanks to its far infrared multiwavelength coverage. However, the lack of a well defined background intensity level in the Herschel data limits the accuracy of the NH and T maps. We aim to provide a method that corrects the missing Herschel background intensity levels using the Planck model for foreground Galactic thermal dust emission. For the Herschel/PACS data, both the constant-offset as well as the spatial dependence of the missing background must be addressed. For the Herschel/SPIRE data, the constant-offset correction has already been applied to the archival data so we are primarily concerned with the spatial dependence, which is most important at 250um. We present a Fourier method that combines the publicly available Planck model on large angular scales with the Herschel images on smaller angular scales. We have applied our method to two regions spanning a range of Galactic environments: Perseus and the Galactic plane region around l=11{deg} (HiGal-11). We post-processed the combined dust continuum emission images to generate column density and temperature maps. We compared these to previously adopted constant-offset corrections. We find significant differences (>~20%) over significant (~15%) areas of the maps, at low column densities (N_H_<~10^22^cm^-2^) and relatively high temperatures (T>~20K). We have also applied our method to synthetic observations of a simulated molecular cloud to validate our method. Our method successfully corrects the Herschel images, including both the constant-offset intensity level and the scale-dependent background variations measured by Planck. Our method improves the previous constant-offset corrections, which did not account for variations in the background emission levels.2017A&A...604A..65Ahttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/604/A65CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/604/A65https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/604/A65http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/604/A65https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/604/A65https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/604/A65http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/604/A65GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/604/A65/list (List of fits files)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/604/A65/list?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/604/A65/list?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/604/A65/list?GETtext/xml+votable180.050000true272.3045-19.412830.0055555555555555566/859 862 29097https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/604/A65?format=asciiRadiodefaultJ/A+A/604/A65/listList of fits filesFileNameName of FITS file, in subdirectory fits (1)meta.id;meta.fitscharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Right Ascension of center (J2000)degpos.eq.ra;meta.mainDEJ2000Declination of center (J2000)degpos.eq.dec;meta.mainNxNumber of pixels along X-axismeta.numberintNyNumber of pixels along Y-axismeta.numberintsizeSize of FITS fileKibytephys.size;meta.fitsintTitleTitle of the FITS filemeta.title;meta.fitschar