Relativistic X-ray Reflection Models for Accreting Neutron Stars

TL;DR

This paper introduces new relativistic X-ray reflection models tailored for accreting neutron stars, accounting for their unique blackbody primary spectra, and demonstrates their effectiveness with observational data and future mission simulations.

Contribution

The paper develops and publicly releases xillverNS and relxillNS models, specifically designed for neutron star accretion disks with blackbody continua, enhancing reflection spectroscopy tools.

Findings

Models fit well with NuSTAR data of 4U 1705-44

Simulations show high diagnostic potential for future missions

Models differ significantly from black hole reflection models

Abstract

We present new reflection models specifically tailored to model the X-ray radiation reprocessed in accretion disks around neutron stars, in which the primary continuum is characterized by a single temperature blackbody spectrum, emitted either at the surface of the star, or at the boundary layer. These models differ significantly from those with a standard power-law continuum, typically observed in most accreting black holes. We show comparisons with earlier reflection models, and test their performance in the NuSTAR observation of the neutron star 4U 1705-44. Simulations of upcoming missions such as XRISM-Resolve and Athena X-IFU are shown to highly the diagnostic potential of these models for high-resolution X-ray reflection spectroscopy. These new reflection models xillverNS, and their relativistic counterpart relxillNS, are made publicly available to the community as an additional flavor in the relxill suite of reflection models.