Determination of basic neutron star parameters from spectral modeling of X-ray bursters

测量中子星半径和质量是研究超核密度下物质性质的重要工具。由于高通量、大亮度变化和光谱性质的相关变化，低质量x射线双星中NSs的热核x射线爆发期间的热发射为确定NSs参数提供了独特的机会。本文介绍了利用热NS大气模型将观测到的x射线暴冷却阶段的光谱演变转化为Eddington通量和恒星角尺寸的冷却尾方法。然后将这些转化为对质量和半径的约束。在这个项目中，我们将调查和消除可能影响结果的系统不确定性，即爆发期间恒星旋转和大气膨胀的影响。我们还将探索一种约束NS参数的新方法。

Measuring neutron star (NS) radii and masses is an essential tool to investigate the properties of matter at super-nuclear densities. Thermal emission during thermonuclear X-ray bursts from NSs in low-mass X-ray binaries provides a unique opportunity to determine NS parameters, because of the high fluxes, large luminosity variations and the related changes in the spectral properties. We introduced the cooling tail method that uses hot NS atmosphere models to convert the observed spectral evolution during cooling stages of X-ray bursts to the Eddington flux and the stellar angular size. These are then translated to constraints on mass and radius. In this project we will investigate and eliminate systematic uncertainties which can potentially affect the results, namely the effects of stellar rotation and atmosphere expansion during the burst. We will also explore a new approach to constrain NS parameters.