BEYONDPLANCK

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Abstract
We present the intensity foreground algorithms and model employed within the BEYONDPLANCKanalysis framework. The BEYONDPLANCKanalysis is aimed at integrating component separation and instrumental parameter sampling within a global framework, leading to complete end-to-end error propagation in thePlanckLow Frequency Instrument (LFI) data analysis. Given the scope of the BEYONDPLANCKanalysis, a limited set of data is included in the component separation process, leading to foreground parameter degeneracies. In order to properly constrain the Galactic foreground parameters, we improve upon the previousCommandercomponent separation implementation by adding a suite of algorithmic techniques. These algorithms are designed to improve the stability and computational efficiency for weakly constrained posterior distributions. These are: (1) joint foreground spectral parameter and amplitude sampling, building on ideas from MIRAMARE; (2) component-based monopole determination; (3) joint spectral parameter and monopole sampling; and (4) application of informative spatial priors for component amplitude maps. We find that the only spectral parameter with a significant signal-to-noise ratio using the current BEYONDPLANCKdata set is the peak frequency of the anomalous microwave emission component, for which we findνp = 25.3 ± 0.5 GHz; all others must be constrained through external priors. Future works will be aimed at integrating many more data sets into this analysis, both map and time-ordered based, thereby gradually eliminating the currently observed degeneracies in a controlled manner with respect to both instrumental systematic effects and astrophysical degeneracies. When this happens, the simple LFI-oriented data model employed in the current work will need to be generalized to account for both a richer astrophysical model and additional instrumental effects. This work will be organized within the Open Science-based COSMOGLOBEcommunity effort.
Funding Information
  • European Union (776282, 772253, 819478)
  • Research Council of Norway (263011, 274990)
  • Tekes, Academy of Finland (295113)
  • ESA
  • ASI and INAF
  • NASA and DoE
  • CSC, and Magnus Ehrnrooth foundation
  • PRACE

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