Fourier-space combination of Planck and Herschel images

• Verfasst von: Abreu Vicente, Jorge [VerfasserIn]
• Verfasst von: Ballesteros-Paredes, Javier [VerfasserIn]
• Titel: Fourier-space combination of Planck and Herschel images
• Verf.angabe: J. Abreu-Vicente, A. Stutz, Th Henning, E. Keto, J. Ballesteros-Paredes, and T. Robitaille
• E-Jahr: 2017
• Jahr: 07 August 2017
• Umfang: 13 S.
• Teil: volume:604
• Teil: year:2017
• Teil: elocationid:A65
• Teil: extent:13
• Fussnoten: Gesehen am 26.09.2018
• Titel Quelle: Enthalten in: Astronomy and astrophysics
• Ort Quelle: Les Ulis : EDP Sciences, 1969
• Jahr Quelle: 2017
• Band/Heft Quelle: 604(2017), Artikel-ID A65
• ISSN Quelle: 1432-0746
• DOI: doi:10.1051/0004-6361/201628891
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 1581310749

Abstract

<i>Context. <i/><i>Herschel<i/> has revolutionized our ability to measure column densities (<i>N<i/><sub>H<sub/>) and temperatures (<i>T<i/>) of molecular clouds thanks to its far infrared multiwavelength coverage. However, the lack of a well defined background intensity level in the <i>Herschel<i/> data limits the accuracy of the <i>N<i/><sub>H<sub/> and <i>T<i/> maps. <i>Aims. <i/>We aim to provide a method that corrects the missing <i>Herschel<i/> background intensity levels using the <i>Planck <i/>model for foreground Galactic thermal dust emission. For the <i>Herschel<i/>/PACS data, both the constant-offset as well as the spatial dependence of the missing background must be addressed. For the <i>Herschel<i/>/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 250 <i>μ<i/>m.<i>Methods. <i/>We present a Fourier method that combines the publicly available <i>Planck <i/>model on large angular scales with the <i>Herschel<i/> images on smaller angular scales.<i>Results. <i/>We have applied our method to two regions spanning a range of Galactic environments: Perseus and the Galactic plane region around <i>l<i/> = 11deg (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 (<i>N<i/><sub>H<sub/> ≲ 10<sup>22<sup/> cm<sup>-2<sup/>) and relatively high temperatures (<i>T<i/> ≳ 20 K). We have also applied our method to synthetic observations of a simulated molecular cloud to validate our method.<i>Conclusions. <i/>Our method successfully corrects the <i>Herschel<i/> images, including both the constant-offset intensity level and the scale-dependent background variations measured by <i>Planck<i/>. Our method improves the previous constant-offset corrections, which did not account for variations in the background emission levels.