Title: Cyclotron resonant scattering feature simulations. II. Description of the CRSF simulation process,
Abstract: Cyclotron resonant scattering features (CRSFs) are formed by scattering of
X-ray photons off quantized plasma electrons in the strong magnetic field (of
the order 10^12 G) close to the surface of an accreting X-ray pulsar. The line
profiles of CRSFs cannot be described by an analytic expression. Numerical
methods such as Monte Carlo (MC) simulations of the scattering processes are
required in order to predict precise line shapes for a given physical setup,
which can be compared to observations to gain information about the underlying
physics in these systems.
A versatile simulation code is needed for the generation of synthetic
cyclotron lines. Sophisticated geometries should be investigatable by making
their simulation possible for the first time.
The simulation utilizes the mean free path tables described in the first
paper of this series for the fast interpolation of propagation lengths. The
code is parallelized to make the very time consuming simulations possible on
convenient time scales. Furthermore, it can generate responses to
mono-energetic photon injections, producing Green's functions, which can be
used later to generate spectra for arbitrary continua.
We develop a new simulation code to generate synthetic cyclotron lines for
complex scenarios, allowing for unprecedented physical interpretation of the
observed data. An associated XSPEC model implementation is used to fit
synthetic line profiles to NuSTAR data of Cep X-4. The code has been developed
with the main goal of overcoming previous geometrical constraints in MC
simulations of CRSFs. By applying this code also to more simple, classic
geometries used in previous works, we furthermore address issues of code
verification and cross-comparison of various models. The XSPEC model and the
Green's function tables are available online at
this http URL .