论文标题
银河系凸起中的周期性X射线源：Gregory-Loredo算法的应用
Periodic X-ray Sources in the Galactic Bulge: Application of the Gregory-Loredo Algorithm
论文作者
论文摘要
我们对限制窗口（LW）中的定期X射线源进行了系统的研究，$ \ sim $ 70 Arcmin $^2 $内部银河凸起的现场代表以及$ \ sim $ 1 MS Chandra观察的目标。使用Gregory-Loredo算法，该算法将贝叶斯定理应用于相折叠的光曲线，非常适合不规则采样的X射线数据，我们在23个离散来源中检测到25个周期性信号，其中15个信号是新的发现，有两个新的发现，两个来源显示了双重时期。 23个周期源中的绝大多数被归类为磁性灾难变量（CVS），基于其周期范围，X射线亮度，光谱特性和相位折叠的光曲线，这些光曲线是自旋调制的特征。同时，由于被视为周期性来源的非磁性简历很少，这可以理解为由于远程来源的检测效率较低所致。在合理的关于磁性CV的几何形状和大量模拟的X射线光曲线的假设下，我们估计银河内部凸起中磁性CV的比例为$ \ lyssim $ 23％，这与太阳能邻居中的磁性CV分别为23％。与太阳能社区中已知的CV范围相比，LW显然缺乏长期（$ \ gtrsim $ 3.3小时）的CV。我们建议这可能是一种年龄效应，从某种意义上说，内部凸起中的CV是进化的系统，并且大大缩小了它们的轨道。
We present a systematic study of periodic X-ray sources in the Limiting Window (LW), a $\sim$70 arcmin$^2$ field representative of the inner Galactic bulge and the target of $\sim$1 Ms Chandra observations. Using the Gregory-Loredo algorithm, which applies Bayes's theorem to the phase-folded light curve and is well-suited for irregularly sampled X-ray data, we detect 25 periodic signals in 23 discrete sources, among which 15 signals are new discoveries and two sources show dual periods. The vast majority of the 23 periodic sources are classified as magnetic cataclysmic variables (CVs), based on their period range, X-ray luminosities, spectral properties, and phase-folded light curves that are characteristic of spin modulation. Meanwhile, there is a paucity of non-magnetic CVs seen as periodic sources, which can be understood as due to a low detection efficiency for eclipsing sources. Under reasonable assumptions about the geometry of magnetic CVs and a large set of simulated X-ray light curves, we estimate the fraction of magnetic CVs in the inner Galactic bulge to be $\lesssim$23%, which is similar to that in the solar neighborhood. There is an apparent lack of long-period ($\gtrsim$3.3 hours) CVs in the LW, when contrasted with the range of known CVs in the solar neighborhood. We suggest that this might be an age effect, in the sense that CVs in the inner bulge are more evolved systems and have substantially shrunk their orbits.
