J/A+A/604/A65 Planck and Herschel images combination (Abreu-Vicente+, 2017)
Fourier-space combination of Planck and Herschel images.
Abreu-Vicente J., Stutz A., Henning T., Keto E., Ballesteros-Paredes J.,
Robitaille T.
<Astron. Astrophys. 604, A65 (2017)>
=2017A&A...604A..65A 2017A&A...604A..65A (SIMBAD/NED BibCode)
ADC_Keywords: Interstellar medium ; Photometry, millimetric/submm
Keywords: submillimeter: ISM - infrared: ISM - techniques: image processing -
ISM: structure
Abstract:
Herschel has revolutionized our ability to measure column densities
(NH) 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°
(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 (NH≲1022cm-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.
Description:
We provide a method that combines the Herschel and Planck data in the
Fourier space. Our method corrects the missing Herschel background
intensity levels using the Planck model for foreground Galactic
thermal dust emission. We apply our method to two regions spanning a
range of Galactic environments: Perseus and the Galactic plane region
around l=11°. We post-process the combined dust continuum
emission images to generate column density and temperature maps.
In this file we show the original Herschel and Planck products used to
obtain our new combined images, also attached. We further provide the
column density and temperature maps of Perseus and HiGaL 11 obtained
through our new images.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 166 40 List of fits files
fits/* . 40 Individual fits files
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 23 I4 --- Nx Number of pixels along X-axis
25- 28 I4 --- Ny Number of pixels along Y-axis
30- 35 I6 Kibyte size Size of FITS file
37- 73 A37 --- FileName Name of FITS file, in subdirectory fits (1)
75-166 A92 --- Title Title of the FITS file
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Note (1): Fluxes are in Jy/arcsec2, column densities in cm-2 and
temperatures in K.
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Acknowledgements:
Jorge Abreu-Vicente, abreu(at)mpia.de
Max-Planck Institute for Astronomy
(End) J. Abreu-Vicente [Max-Planck Inst. Astron.], P. Vannier [CDS] 28-Jun-2017