Speaker
Description
We present Monte Carlo calculations of accretion disk illumination by a neutron star spreading layer and derive the corresponding radial profiles of Fe-K photoionizing flux. In contrast to the phenomenological emissivity prescriptions commonly used when fitting reflection spectra, our model is directly tied to the physical geometry of the illuminating area on the stelar surface. We show that the resulting radial profiles depend systematically on two key parameters: the neutron star compactness and the full opening angle of the spreading layer. The profiles are well described by a smoothly broken power law and may serve as a physically motivated input for improved modeling of relativistic iron line reflection in neutron star low mass X-ray binaries.