Polarization properties of weakly magnetized Neutron Stars in Low Mass X-ray Binaries

TL;DR

This paper simulates the expected X-ray polarization signals from weakly magnetized neutron stars in Low Mass X-ray Binaries, demonstrating how different coronal geometries influence polarization properties, aiding future observational constraints.

Contribution

It introduces relativistic Monte Carlo simulations of X-ray polarization for various coronal geometries around neutron stars, providing a tool for interpreting upcoming polarimetry data.

Findings

Different coronal geometries produce distinct polarization signatures.

Simulations show polarization degree and angle depend on coronal shape.

Results can help constrain system geometry with future observations.

Abstract

X-ray polarimetry missions like IXPE will be able to measure for the first time the polarization properties of accreting, weakly magnetized neutron stars in Low Mass X-ray Binaries. In this work we present simulations of the expected X-ray polarized signal including the coronal emission for different geometries of the corona itself, i.e. a slab above the accretion disc and a spherical shell around the neutron star. The simulations are performed with the fully relativistic Monte Carlo code monk capable of computing the X-ray polarization degree and angle for various physical input parameters of the neutron star, disc and corona. Different coronal geometries result in significantly different X-ray polarization properties, which can therefore be used to constrain the geometry of the systems.