pollin: Linearly dependent polarization

This multiplicative model applies a polarization with a linear dependence on energy. The factor applied depends on which Stokes parameter the spectrum is for. The Stokes parameter is determined using an XFLTnnnn keyword with values “Stokes:0”, “Stokes:1”, or “Stokes:2”, for I, Q, U, respectively.

The fraction and angle are determined by

The parameters are :

par1 | A1, the polarization fraction at 1 keV |

par2 | Aslope, the polarization fraction slope |

par3 | psi1, the polarization angle at 1 keV (degrees) |

par4 | psislope, the polarization angle slope |