Type-A quasi-periodic oscillation in the black hole transient MAXI J1348−630
Type-A quasi-periodic oscillation in the black hole transient MAXI J1348−630
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DOI：
10.1093/mnras/stad3062
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发表时间：
2023-10
影响因子：
4.8
通讯作者：
Liang Zhang;Mariano Méndez;Federico García;Yuexin Zhang;R. Ma;D. Altamirano;Zi-Xu Yang;
中科院分区：
文献类型：
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作者：
Liang Zhang;Mariano Méndez;Federico García;Yuexin Zhang;R. Ma;D. Altamirano;Zi-Xu Yang;
我们对黑洞 X 射线双星 MAXI J1348−630 在其高软状态期间的 NICER 观测中检测到的 7 Hz A 型准周期振荡 (QPO) 的光谱和定时特征进行了详细分析。 QPO 宽且弱，在 0.5-10 keV 频段内积分均方根振幅为 0.9%。得益于NICER的大有效面积，结合光源的高通量和相对较长的累积曝光时间，我们构建了A型QPO的第一个均方根谱和相位滞后谱。我们的分析表明，QPO 的分数均方根振幅随着能量的增加而增加，从 1 keV 时的低于 1% 到 6 keV 时的~3%。 QPO 谱的形状与 Comptonized 分量的形状相似，表明 Comptonized 区域正在驱动变异性。以最低能量为参考，QPO 频率处的相位滞后始终是软的。通过将源的时间平均谱以及 QPO 的均方根和相位滞后谱与时间相关的康普顿化模型 vkompthdk 联合拟合，我们发现 A 型 QPO 的辐射特性可以通过垂直延伸的康普顿化区域来解释，该区域的大小约为 2300 km。
We present a detailed analysis of the spectral and timing characteristics of a 7-Hz type-A quasi-periodic oscillation (QPO) detected in NICER observations of the black hole X-ray binary MAXI J1348−630 during its high-soft state. The QPO is broad and weak, with an integrated fractional rms amplitude of 0.9 per cent in the 0.5–10 keV band. Thanks to the large effective area of NICER, combined with the high flux of the source and a relatively long accumulative exposure time, we construct the first rms and phase-lag spectra for a type-A QPO. Our analysis reveals that the fractional rms amplitude of the QPO increases with energy from below 1 per cent at 1 keV to ∼3 per cent at 6 keV. The shape of the QPO spectrum is similar to that of the Comptonized component, suggesting that the Comptonized region is driving the variability. The phase lags at the QPO frequency are always soft taking the lowest energy as reference. By jointly fitting the time-averaged spectrum of the source and the rms and phase-lag spectra of the QPO with the time-dependent Comptonization model vkompthdk, we find that the radiative properties of the type-A QPO can be explained by a vertically extended Comptonized region with a size of ∼2300 km.