Used to calculate a set of well-educated constant spectral indices βS and βD and clean out the spatially-constant part of the foregrounds at the map-level. In practice, a filter Q is returned that de-projects the linear combinations of the data that follow the best-fit SEDs of the foreground sources under consideration (dust and synchrotron).
The outputs are directly compatible with the inputs to BBPipe, its submodule BBPower. The inputs can be generated with BBSims.
Ref: A hybrid map-Cℓ component separation method for primordial CMB B-mode searches
Developed by: Susanna Azzoni, Max Abitbol, David Alonso