论文标题
GX 17+2的正常分支的冠状垂直结构变化：AstrosaťsSXT和LAXPC透视图
Coronal Vertical Structure Variations in Normal Branch of GX 17+2 : AstroSaťs SXT and LAXPC perspective
论文作者
论文摘要
我们使用Astrosat软X射线望远镜（SXT）和大面积X射线比例计数器（LAXPC）数据进行了中子星Z源GX 17+2的0.8--50 keV能带的光谱 - 周期分析。发现源在硬度强度图的正常分支中有所不同。在柔软的和硬X射线带中LAXPC光曲线的互相关研究揭示了几百秒的反相关滞后。首次使用SXT软和LaxPC硬弯曲进行了互相关研究，它们表现出一百秒的相关和反相关的滞后。功率密度光谱显示为6.7--7.8 Hz的NB振荡（质量因子1.5---4.0）。光谱建模导致内部磁盘半径为$ \ sim $ 12--16 km，$γ$ \ sim $ \ sim $ 2.31--2.44，表明磁盘接近ISCO，并且根据反射模型注意到了磁盘半径的相似值。使用不同的方法来限制GX 17+2中的电晕尺寸。使用检测到的滞后，发现电晕尺寸为27-46公里（$β$ = 0.1，$β$ = V $ _ {Corona} $/V $ _ {disk} $）和138--231 km（$β$ = 0.5）。假设X射线发射是由边界层（BL）产生的，则确定其大小为57--71 km。假设BL正在电离磁盘的内部区域，则大小约束至$ \ sim $ 19--86公里。使用NBO频率，发现过渡壳半径约为32 km。观察到的滞后和内部磁盘前部没有运动强烈表明，变化的电晕结构正在引起Z源GX 17+2的NB的X射线变化。
We performed spectro-temporal analysis in the 0.8--50 keV energy band of the neutron star Z source GX 17+2 using AstroSat Soft X-ray Telescope (SXT) and Large Area X-ray Proportional Counter (LAXPC) data. The source was found to vary in the normal branch of the Hardness Intensity Diagram. Cross-correlation studies of LAXPC light curves in soft and hard X-ray band unveiled anticorrelated lags of the order of few hundred seconds. For the first time, Cross-correlation studies were performed using SXT soft and LAXPC hard lightcurves and they exhibited correlated and anti-correlated lags of the order of a hundred seconds. Power density spectrum displayed NB oscillations of 6.7--7.8 Hz (quality factor 1.5--4.0). Spectral modeling resulted in inner disk radius of $\sim$ 12--16 km with $Γ$ $\sim$ 2.31--2.44 indicating that disk is close to the ISCO and a similar value of disk radius was noticed based on the reflection model. Different methods were used to constrain the corona size in GX 17+2. Using the detected lags, corona size was found to be 27-46 km ($β$ = 0.1, $β$ = v$_{corona}$/v$_{disk}$) and 138--231 km ($β$ = 0.5). Assuming the X-ray emission to be arising from the Boundary Layer (BL), its size was determined to be 57--71 km. Assuming that BL is ionizing the disk's inner region, it's size was constrained to $\sim$ 19--86 km. Using NBO frequency, the transition shell radius was found to be around 32 km. Observed lags and no movement of the inner disk front strongly indicates that the varying corona structure is causing the X-ray variation in the NB of Z source GX 17+2.
