Model atmospheres of X-ray bursting neutron stars

TL;DR

This paper provides an extensive set of neutron star atmosphere models accounting for Compton scattering, covering various compositions, gravities, and luminosities, with implications for estimating neutron star parameters from X-ray spectra.

Contribution

It introduces a comprehensive grid of LTE model atmospheres for neutron stars with different compositions and physical parameters, including emergent spectra and color correction factors.

Findings

Models fit by diluted blackbody spectra in 3-20 keV band

Color correction factors depend on composition and luminosity

Framework for estimating neutron star parameters from spectra

Abstract

We present an extended set of model atmospheres and emergent spectra of X-ray bursting neutron stars in low mass X-ray binaries. Compton scattering is taken into account. The models were computed in LTE approximation for six different chemical compositions: pure hydrogen and pure helium atmospheres, and atmospheres with a solar mix of hydrogen and helium and various heavy elements abundances: Z = 1, 0.3, 0.1, and 0.01 Z_sun, for three values of gravity, log g =14.0, 14.3, and 14.6 and for 20 values of relative luminosity l = L/L_Edd in the range 0.001 - 0.98. The emergent spectra of all models are fitted by diluted blackbody spectra in the observed RXTE/PCA band 3 - 20 keV and the corresponding values of color correction factors f_c are presented. We also show how to use these dependencies to estimate the neutron star's basic parameters.