PR2 and PR3 Legacy CMB and Astrophysical Component Maps

Astrophysical Component Maps. The maps of astrophysical components (AME, CIB, CO, Thermal Dust, FreeFree, ISW and Synchrotron) have been 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. All the details can be found in Planck 2018 results IV and Planck 2018 VIII. Commanderderived astrophysical foreground map. As discussed in detail in Planck 2018 results IV, 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 Planck2018 results III, 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 singledetector 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 results X 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 release, namely synchrotron and thermal dust emission. For synchrotron emission, a spatially constant spectral index of β3.1 is a[truncated, see actual data for full text]