AI 中文总结
本研究通过XMM-Newton和NuSTAR望远镜观测数据，探测到中子星低质量X射线双星4U 1323-62中可能的暴振荡信号，对应毫秒级快速旋转中子星，为相关研究提供了试探性证据。
AI 中文摘要
热核X射线暴期间观测到的暴振荡源于中子星表面的不对称亮度分布，是直接探测中子星自旋频率的手段。本研究利用XMM-Newton和NuSTAR望远镜2024年对中子星低质量X射线双星4U 1323-62的观测数据开展详细计时分析，在XMM-Newton/EPIC-pn数据中识别出9次热核X射线暴及光变曲线中的食 dip，其中一次XMM-Newton暴呈现罕见的双峰结构；NuSTAR探测到6次暴，其中4次与XMM-Newton观测到的暴同时发生。在XMM-Newton数据中识别出~611.5 Hz的可能暴振荡信号，该信号在双峰暴的主暴期间被探测到，最强Z₁²功率达~35。考虑搜索频率和时间间隔的解析估计给出~3.0σ的显著性，独立蒙特卡洛模拟得到更稳健的全局显著性仅为~2.4σ，因此将该信号解释为暴振荡的试探性探测。0.5-10 keV波段的折叠脉冲轮廓可由正弦函数很好描述，分数均方根振幅为~30±6%，该振荡频率对应中子星自旋周期约1.635 ms，提示4U 1323-62可能拥有一颗快速旋转的毫秒中子星。
英文摘要
Burst oscillations observed during thermonuclear X-ray bursts arise from asymmetric brightness patterns on the neutron star surface and provide a direct probe of the neutron star spin frequency. We present a detailed timing analysis of the neutron star low-mass X-ray binary 4U 1323-62 using 2024 observations with XMM-Newton and NuSTAR observatories. We identify nine thermonuclear X-ray bursts in the XMM-Newton/EPIC-pn data, along with eclipsing dips in the light curve. One of the XMM-Newton bursts exhibits a rare doublet structure. In addition, NuSTAR detects six bursts, four of which occur simultaneously with those observed with XMM-Newton. We identify a possible burst oscillation signal at $\sim$611.5 Hz in the XMM-Newton data. The strongest oscillation, detected during the primary burst of the doublet burst, reaches a maximum $Z_1^{2}$ power of $\sim35$. An analytical estimate accounting for the searched frequency and time intervals gives a significance of $\sim3.0σ$, whereas independent Monte Carlo simulations yield a more robust global significance of only $\sim2.4σ$. We therefore interpret the signal as a tentative detection of burst oscillation. The folded pulse profile in the 0.5-10 keV band is well described by a sinusoid, with a fractional rms amplitude of $\sim30\pm6$%. The oscillation frequency corresponds to a neutron-star spin period of $\sim$1.635 ms, suggesting that 4U 1323-62 may harbor a rapidly rotating millisecond neutron star.
CommentsAccepted for publication in ApJ
