标题： 基于AstroSat观测的GX 13+1能量依赖的时间研究 显示英文标题

标题： Energy-dependent temporal study of GX 13+1 with AstroSat observation

摘要： 在本工作中，我们使用\textit{天体卫星}（大面积X射线比例计数器和软X射线望远镜）对GX 13+1中观测到的低频振荡进行了能量依赖性研究。 观测的硬度-强度图（HID）呈现出类似 `$\nu$` 形状的轨迹，而颜色-颜色图则显示出类似 `$<$` 形状的轨迹，与Z源的水平分支和正常分支相似。 我们进行了通量分辨的时间研究，重点关注低频变化，并将HID分为五个区域：A、B、C、D和E。在区域A、B和C中检测到了低频准周期振荡（QPO）。区域A中的QPO频率为$5.06^{+0.54}_{-0.48}$Hz，品质因数（Q因子）为2.80。 在区域B中，QPO出现在$4.52^{+0.14}_{-0.13}$Hz，Q因子为5.79，而在区域C中，QPO出现在$4.70^{+0.62}_{-0.42}$Hz，Q因子为4.35。 QPO频率、Q因子以及低均方根（rms）值（1.32%、1.34%和0.7%）表明这些振荡是正常分支振荡，类似于在GX 340+0中报告的振荡。 我们使用传播模型对QPO的rms和滞后进行了建模，考虑了黑体温度、日冕加热率和光学深度的变化。 我们的研究结果表明，观测到的QPO可能是由日冕与黑体温度变化之间的相互作用驱动的。 显示英文摘要

摘要： In this work, we performed an energy-dependent study of low-frequency oscillations observed in GX 13+1 using \textit{AstroSat} (Large Area X-ray Proportional Counter and Soft X-ray Telescope). The hardness-intensity diagram (HID) of the observation resembles a `$\nu$'-shaped track, while the color-color diagram exhibits a `$<$'-shaped track, similar to the horizontal and normal branches of the Z source. We conducted flux-resolved temporal studies focusing on low-frequency variability and divided the HID into five regions: A, B, C, D, and E. Low-frequency quasi-periodic oscillations (QPOs) were detected in Regions A, B, and C. The QPO in Region A has a frequency of $5.06^{+0.54}_{-0.48}$ Hz with a quality factor (Q-factor) of 2.80. In Region B, the QPO was detected at $4.52^{+0.14}_{-0.13}$ Hz with a Q-factor of 5.79, while in Region C, it was observed at $4.70^{+0.62}_{-0.42}$ Hz with a Q-factor of 4.35. The QPO frequencies, Q-factors, and low root-mean-square (rms) values (1.32\%, 1.34\%, and 0.7\%) suggest that these oscillations are Normal Branch Oscillations, similar to those reported in GX 340+0. We modeled the rms and lag of the QPOs using a propagative model, considering variations in blackbody temperature, coronal heating rate, and optical depth. Our findings indicate that the observed QPOs are likely driven by interactions between the corona and variations in the blackbody temperature.