论文标题
在Cygnus X-2中〜42 Hz时的Astrosat检测Astrosat检测
AstroSat Detection of a Quasi-periodic Oscillation at ~ 42 Hz in Cygnus X-2
论文作者
论文摘要
我们报告了2016年2月Cygnus X-2观察结果的结果。使用LAXPC数据产生的来源的功率密度谱显示出，在$ \ sim42 $ hz $ \ sim42 $ \ sim10 $ sim10 $ hz的宽带连续噪声中，存在$ \ sim42 $ hz的显着的准周期振荡（QPO）。 LAXPC的较大有效面积为$ \ gtrsim $ 30 KEV允许对QPO和宽噪声连续体的能量依赖性进行前所未有的研究。分数r.m.s随着能量而增加，QPO和连续噪声的形状相似，这表明辐射的起源很常见。但是，尽管QPO表现出较难的时间滞后，而高能量光子的低位光子落在了几毫秒内，但连续噪声显示出相反的行为。 SXT和LAXPC的光子频谱以$ 0.7-30 $ keV频段包含圆盘中的软件和热电晕的硬构成组件。虽然R.M.S的能量依赖性表明QPO和连续噪声的可变性主要由组成的组件主导，但时间延迟的符号的变化表明QPO的动态起源可能在杜松子联中，而噪声连续性可能源于电晕。
We report the results of AstroSat observations of Cygnus X-2 during February 2016. The source's power density spectrum generated using LAXPC data revealed the presence of a prominent Quasi-periodic Oscillation (QPO) at $\sim42$ Hz with broadband continuum noise at lower frequencies at $\sim10$ Hz. The large effective area of LAXPC at $\gtrsim$30 keV allowed for an unprecedented study of the energy dependence of the QPO and the broad noise continuum. The fractional r.m.s increases with energy, and its shape is similar for both the QPO and the continuum noise, suggesting a common radiative origin. However, while the QPO exhibits hard time lags, with the high energy photons lagging the low ones by a few milliseconds, the continuum noise shows the opposite behavior. The photon spectrum from SXT and LAXPC in $0.7-30$ keV band comprises the soft component from a disc and a hard Comptonized component from a hot corona. While the energy dependence of the r.m.s shows that the QPO and the continuum noise variability are dominated by the Comptonized component, the change in sign of the time-lag suggests that the dynamic origin of the QPO may be in the disk while the noise continuum may originate from the corona.
