Foreground maps

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2018 Astrophysical Components[edit]

Overview[edit]

This section describes the maps of astrophysical components produced from the Planck data. These products are derived from some or all of the nine frequency channel maps described above using different techniques and, in some cases, using other constraints from external data sets. Here we give a brief description of each product and how it is obtained, followed by a description of the FITS file containing the data and associated information. All the details can be found in Planck-2020-A4[1] and Planck-2020-A8[2].

Commander-derived astrophysical foreground maps[edit]

As discussed in detail in Planck-2020-A4[1], the main Planck 2018 frequency sky maps have significantly lower systematic errors than earlier versions. At the same time, these maps are also associated with a significant limitation, in that no robust single detector or detector set maps are available. As described in Planck-2020-A3[3], such maps do not contain the full signal content of the true sky. As a result, only full frequency maps are distributed and used in the 2018 analysis.

For polarization analysis, this is not a significant issue, and the 2018 polarization foreground products therefore supersede the 2015 release in all respects. However, for temperature analysis the lack of single-detector maps strongly limits the ability to extract CO line emission from the data set, and it is also not possible to exclude known detector outliers; see Planck-2015-A10[4] for details. For these reasons, we consider the parametric foreground products from 2015 to represent a more accurate description of the true sky than the corresponding 2018 version. As a result, we do not release parametric temperature foreground products from the 2018 data set, but rather recommend continued usage of the 2015 temperature model. For polarization, we recommend usage of the 2018 model.


Two Commander-based polarization foreground products are provided for the Planck 2018 releaes, namely synchrotron and thermal dust emission. For synchrotron emission, a spatially constant spectral index of β=-3.1 is adopted. For thermal dust emission, the dust temperature is fixed to that derived from the corresponding 2018 intensity analysis, while the spectral index is fitted directly from the polarization measurements, smoothed to 3 degrees FWHM. For both synchrotron and thermal dust emission, we provide results derived from both the full-mission data set, and from the half-mission and odd-even splits.

In addition to the real observations, we also provide 300 end-to-end noise simulations processed through the algorithm with the same spectral parameters as derived from the data for each of the data splits. The filenames of these simulations have the following format:

  • dx12_v3_commander_{synch,dust}_noise_{full,hm1,hm2,oe1,oe2}_00???_raw.fits

Inputs[edit]

The following data products are used for the full-mission polarization analysis (corresponding data are used for the data split products):

Outputs[edit]

Synchrotron emission[edit]
Full-mission file name: COM_CompMap_QU_synchrotron-commander_2048_R3.00_full.fits
First half-mission split file name: COM_CompMap_QU_synchrotron-commander_2048_R3.00_hm1.fits
Second half-mission split file name: COM_CompMap_QU_synchrotron-commander_2048_R3.00_hm2.fits
Odd ring split file name: COM_CompMap_QU_synchrotron-commander_2048_R3.00_oe1.fits
Even ring split file name: COM_CompMap_QU_synchrotron-commander_2048_R3.00_oe2.fits
Nside = 2048
Angular resolution = 40 arcmin
Reference frequency: 30 GHz
HDU -- COMP-MAP
Column Name Data Type Units Description
Q_STOKES Real*4 μK_RJ Stokes Q posterior maximum
U_STOKES Real*4 μK_RJ Stokes U posterior maximum
Thermal dust emission[edit]
Full-mission file name: COM_CompMap_QU_thermaldust-commander_2048_R3.00_full.fits
First half-mission split file name: COM_CompMap_QU_thermaldust-commander_2048_R3.00_hm1.fits
Second half-mission split file name: COM_CompMap_QU_thermaldust-commander_2048_R3.00_hm2.fits
Odd ring split file name: COM_CompMap_QU_thermaldust-commander_2048_R3.00_oe1.fits
Even ring split file name: COM_CompMap_QU_thermaldust-commander_2048_R3.00_oe2.fits
Nside = 2048
Angular resolution = 5 arcmin
Reference frequency: 353 GHz
HDU -- COMP-MAP
Column Name Data Type Units Description
Q_STOKES Real*4 uK_RJ Full-mission Stokes Q posterior maximum
U_STOKES Real*4 uK_RJ Full-mission Stokes U posterior maximum
BETA Real*4 Spectral index (full mission only)

SMICA-derived astrophysical foreground maps[edit]

Two SMICA-based polarization foreground products are provided, namely synchrotron and thermal dust emission. These are derived using the usual SMICA spectral matching method, tuned specifically for the reconstruction of two polarized foregrounds. Specifically, three coherent components (plus noise) are fitted at the spectral level with the first one constrained to have CMB emissivity. No assumptions are made regarding the other two components: they are not assumed to have a specific emissivity or angular spectrum, nor are they assumed to be uncorrelated. This leaves a degenerate model but that degeneracy can be entirely fixed after the spectral fit by assuming that synchrotron emission is negligible at 353 GHz and that thermal dust emission is negligible at 30 GHz. For both synchrotron and thermal dust emission, we provide results derived from both the full-mission data set, and from the half-mission and odd-even splits.

In addition to the real observations, we also provide 300 end-to-end noise simulations processed through the algorithm with the same spectral parameters as derived from the data for each of the data splits. The filenames of these simulations have the following format:

  • dx12_v3_smica_{synch,dust}_noise_{full,hm1,hm2,oe1,oe2}_00???_raw.fits

Inputs[edit]

The following data products are used for the full-mission polarization analysis (corresponding data are used for the data split products):

Outputs[edit]

Synchrotron emission[edit]
Full-mission file name: COM_CompMap_QU_synchrotron-smica_2048_R3.00_full.fits
First half-mission split file name: COM_CompMap_QU_synchrotron-smica_2048_R3.00_hm1.fits
Second half-mission split file name: COM_CompMap_QU_synchrotron-smica_2048_R3.00_hm2.fits
Odd ring split file name: COM_CompMap_QU_synchrotron-smica_2048_R3.00_oe1.fits
Even ring split file name: COM_CompMap_QU_synchrotron-smica_2048_R3.00_oe2.fits
Nside = 2048
Angular resolution = 40 arcmin
Reference frequency: Integrated 30 GHz band; no colour corrections have been applied
HDU -- COMP-MAP
Column Name Data Type Units Description
Q_STOKES Real*4 mK_RJ Stokes Q posterior maximum
U_STOKES Real*4 mK_RJ Stokes U posterior maximum
Thermal dust emission[edit]
Full-mission file name: COM_CompMap_QU_thermaldust-smica_2048_R3.00_full.fits
First half-mission split file name: COM_CompMap_QU_thermaldust-smica_2048_R3.00_hm1.fits
Second half-mission split file name: COM_CompMap_QU_thermaldust-smica_2048_R3.00_hm2.fits
Odd ring split file name: COM_CompMap_QU_thermaldust-smica_2048_R3.00_oe1.fits
Even ring split file name: COM_CompMap_QU_thermaldust-smica_2048_R3.00_oe2.fits
Nside = 2048
Angular resolution = 12 arcmin
Reference frequency: Integrated 353 GHz band; no colour corrections have been applied
HDU -- COMP-MAP
Column Name Data Type Units Description
Q_STOKES Real*4 mK_RJ Full-mission Stokes Q posterior maximum
U_STOKES Real*4 mK_RJ Full-mission Stokes U posterior maximum

GNILC thermal dust maps[edit]

The 2018 GNILC thermal dust products are provided as single files that include both intensity and polarization, 3x3 IQU noise covariance matrices per pixel, and as well as local smoothing scale for the variable resolution map. The structure of the data files is the following:

Uniform resolution file name: COM_CompMap_IQU_thermaldust-gnilc-unires_2048_R3.00.fits
Variable resolution file name: COM_CompMap_IQU_thermaldust-gnilc-varres_2048_R3.00.fits
Nside = 2048
Angular resolution = 80 arcmin FWHM, or variable
Reference frequency: Integrated 353 GHz band; no colour corrections have been applied
HDU -- COMP-MAP
Column Name Data Type Units Description
I_STOKES Real*4 K_cmb Stokes I estimate
Q_STOKES Real*4 K_cmb Stokes Q estimate
U_STOKES Real*4 K_cmb Stokes U estimate
II_COV Real*4 K_cmb^2 Covariance matrix II element
IQ_COV Real*4 K_cmb^2 Covariance matrix IQ element
IU_COV Real*4 K_cmb^2 Covariance matrix IU element
QQ_COV Real*4 K_cmb^2 Covariance matrix QQ element
QU_COV Real*4 K_cmb^2 Covariance matrix QU element
UU_COV Real*4 K_cmb^2 Covariance matrix UU element
FWHM Real*4 arcmin Local FWHM smoothing scale

Previous Releases: (2015) and (2013) Foreground Maps[edit]

Expand

Astrophysical components based on the 2015 data release

Expand

Astrophysical components based on the 2013 data release

References[edit]

  1. Jump up to: 1.01.1 Planck 2018 results. IV. Diffuse component separation, Planck Collaboration, 2020, A&A, 641, A4.
  2. Jump up Planck 2018 results. VIII. Lensing, Planck Collaboration, 2020, A&A, 641, A8.
  3. Jump up Planck 2018 results. III. High Frequency Instrument data processing and frequency maps, Planck Collaboration, 2020, A&A, 641, A3.
  4. Jump up to: 4.04.14.2 Planck 2015 results. X. Diffuse component separation: Foreground maps, Planck Collaboration, 2016, A&A, 594, A10.
  5. Jump up to: 5.05.15.25.3 Planck 2015 results. XXV. Diffuse low frequency Galactic foregrounds, Planck Collaboration, 2016, A&A, 594, A25.
  6. Jump up Planck intermediate results. XXIX. All-sky dust modelling with Planck, IRAS, and WISE observations', Planck Collaboration Int. XXIX, A&A, 586, A132, (2016).
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  10. Jump up to: 10.010.110.210.310.410.510.610.7 Planck 2013 results. XI. Component separation, Planck Collaboration, 2014, A&A, 571, A11.
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  16. Jump up to: 16.016.1 Planck 2013 results. XII. All-sky model of thermal dust emission, Planck Collaboration, 2014, A&A, 571, A12.
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Flexible Image Transfer Specification

Full-Width-at-Half-Maximum

Cosmic Microwave background

Sunyaev-Zel'dovich

Planck Legacy Archive

(Hierarchical Equal Area isoLatitude Pixelation of a sphere, <ref name="Template:Gorski2005">HEALPix: A Framework for High-Resolution Discretization and Fast Analysis of Data Distributed on the Sphere, K. M. Górski, E. Hivon, A. J. Banday, B. D. Wandelt, F. K. Hansen, M. Reinecke, M. Bartelmann, ApJ, 622, 759-771, (2005).

(Planck) Low Frequency Instrument

(Planck) High Frequency Instrument

reduced IMO