Model X-ray Spectra of Magnetic Neutron Stars with Hydrogen Atmospheres

TL;DR

This paper develops detailed hydrogen atmosphere models for magnetized neutron stars, enabling improved interpretation of their X-ray spectra and incorporating these models into XSPEC for broader community use.

Contribution

It introduces new partially ionized hydrogen atmosphere models for neutron stars with magnetic fields up to 2x10^13 G, based on the latest physics, and makes them accessible via XSPEC.

Findings

Models cover a range of magnetic fields and temperatures.

Inclusion of latest equation of state and opacity data.

Models are integrated into XSPEC for observational fitting.

Abstract

We construct partially ionized hydrogen atmosphere models for magnetized neutron stars in radiative equilibrium with fixed surface fields between B=10^12 and 2x10^13 G and effective temperatures logT_eff=5.5-6.8, as well as with surface B and T_eff distributions around these values. The models are based on the latest equation of state and opacity results for magnetized, partially ionized hydrogen plasmas. The atmospheres directly determine the characteristics of thermal emission from the surface of neutron stars. We also incorporate these model spectra into XSPEC, under the model name NSMAX, thus allowing them to be used by the community to fit X-ray observations of neutron stars.