标题： 中子星原子光谱特征的旋转展宽 显示英文标题

标题： Rotational Broadening of Atomic Spectral Features from Neutron Stars

摘要： Cottam、Paerels 和 Mendez 发现了来自中子星（NS）的首条引力红移谱线，这一发现引发了关于中子星大气中原子线形成的物理机制的理论研究。Chang、Bildsten 和 Wasserman 表明，在爆发中子星光球层上方形成的氢化铁（Fe H$\alpha$）线本质上是宽的。我们现在在广义相对论框架内考虑旋转展宽，并将由此产生的轮廓与 EXO 0748-676 的 I 型爆发期间观测到的轮廓进行比较。我们证明了该线的精细结构分裂排除了对半径施加有意义约束的可能性。我们的数据分析表明，形成 Fe 的柱密度为${\rm log}_{10} (N_{\rm Fe, n=2}/{\rm cm^{-2}})=17.9_{-0.42}^{+0.27}$，引力红移为$1+z =1.345_{-0.008}^{+0.005}$，置信度为 95%。我们假设发射来自整个表面，计算了这种光谱特征在大量自旋和倾角下的可探测性。我们发现，在 300 Hz（600 Hz）时，只有 10%-20%（5%-10%）的中子星会有像 EXO 0748-676 中看到的那样深的光谱特征。 显示英文摘要

摘要： The discovery of the first gravitationally redshifted spectral line from a neutron star (NS) by Cottam, Paerels and Mendez has triggered theoretical studies of the physics of atomic line formation in NS atmospheres. Chang, Bildsten and Wasserman showed that the hydrogenic Fe H$\alpha$ line formed above the photosphere of a bursting NS is intrinsically broad. We now include rotational broadening within general relativity and compare the resulting profile to that observed during Type I bursts from EXO 0748-676. We show that the fine structure splitting of the line precludes a meaningful constraint on the radius. Our fitting of the data show that the line forming Fe column is ${\rm log}_{10} (N_{\rm Fe, n=2}/{\rm cm^{-2}})=17.9_{-0.42}^{+0.27}$ and gravitational redshift $1+z =1.345_{-0.008}^{+0.005}$ with 95% confidence. We calculate the detectability of this spectral feature for a large range of spins and inclinations assuming that the emission comes from the entire surface. We find that at 300 (600) Hz only 10-20% (5-10%) of NSs would have spectral features as deep as that seen in EXO 0748-676.