论文标题
X射线二进制1RXS J180408.9 $ - $ 342058中的Millihertz准周期振荡检测
Detection of Millihertz Quasi-Periodic Oscillations in the X-Ray Binary 1RXS J180408.9$-$342058
论文作者
论文摘要
Millihertz准周期振荡（MHz QPOS）在中子低质量X射线二进制（NS LMXB）中观察到，通常被解释为在中子星表面上的边缘稳定的热核燃烧。我们报告了在XMM-Newton对瞬态1RXS J180408.9 $ - $ 342058的XMM-Newton观察中发现MHz QPO的发现，其在其2015年爆发的常规爆发阶段。我们在3月的观察中发现了重大的周期性信号，其频率在$ 5-8 \，\ mathrm {MHz} $中，叠加在强$ \ sim1/f $ powerlaw噪声连续体上。在四月观察期间，QPO信号和幂律噪声都没有存在，该观察表现出$ 2.5 \ tims $更高的发光度，并且相应地频繁出现。当存在时，QPO信号功率在突发期间降低并随后消失，类似于其他来源的行为。 1RXS J180408.9 $ - $ 342058是迄今为止已知的第八个来源，该来源表现出由热核燃烧驱动的QPO。我们检查了不同来源中QPO信号的属性范围。尽管观察到的振荡曲线与数值模型所预测的振动曲线相似，但幅度明显更高，挑战了它们的解释，因为它们源于略有稳定的燃烧。
Millihertz quasi-periodic oscillations (mHz QPOs) observed in neutron-star low-mass X-ray binaries (NS LMXBs) are generally explained as marginally stable thermonuclear burning on the neutron star surface. We report the discovery of mHz QPOs in an XMM-Newton observation of the transient 1RXS J180408.9$-$342058, during a regular bursting phase of its 2015 outburst. We found significant periodic signals in the March observation, with frequencies in the range $5-8\,\mathrm{mHz}$, superimposed on a strong $\sim1/f$ power-law noise continuum. Neither the QPO signals nor the power-law noise were present during the April observation, which exhibited a $2.5\times$ higher luminosity and had correspondingly more frequent bursts. When present, the QPO signal power decreases during bursts and disappears afterwards, similar to the behaviour in other sources. 1RXS J180408.9$-$342058 is the eighth source known to date that exhibits such QPOs driven by thermonuclear burning. We examine the range of properties of the QPO signals in different sources. Whereas the observed oscillation profile is similar to that predicted by numerical models, the amplitudes are significantly higher, challenging their explanation as originating from marginally stable burning.
