Compton scattering in the optically thick uniform spherical corona around the neutron star in an X-ray binary in two conditions

TL;DR

This study shows that Compton scattering in an optically thick spherical corona around a neutron star can be approximated by layered scattering, simplifying the analysis of physical processes in the corona.

Contribution

It introduces the concept of approximate invariance in Compton scattering between whole and layered corona models, aiding simplified modeling of X-ray binary coronae.

Findings

Layered and whole corona scattering produce similar output photon numbers.

Approximate invariance allows layered models to represent whole corona scattering.

Simplifies analysis of physical processes in the corona.

Abstract

We consider the Compton scattering in the optically thick uniform spherical corona around a neutron star in an X-ray binary. In the scattering, the low energy seed photons (0.1 - 2.5 keV) are scattered in low energy electrons (2.5 - 10 keV) in the corona in two conditions, i.e. initial seed photons are scattered in a whole corona and scattered in every layer of the corona that are supposed to be divided into many layers.When the same number of input seed photons, the same corona parameters and the same energy distribution of all photons in the two conditions are considered, the approximately same number of output photons can be obtained, which means that there is approximately a transform invariance of layering the Comptonized corona. Thus the scattering in the layers of a multi-layered corona is approximately equal to the scattering in the whole corona by dividing the whole corona into several layers.It means that Compton scattering for the initial seed photons scattered in a whole optically thick spherical corona with uniformly distributed electrons also can be considered as that the multiple Compton scatterings take place in the layers of a multi-layered corona in order approximately, which can be used to explore some physical process in one part of a corona.