For the first time, we present a Bayesian time-resolved spectral study of the X-ray afterglow datasets of GW170817/GRB17017A observed by the Chandra X-ray Observatory. These include all 12 public datasets, from the earliest observation taken at $t\sim 9$ d to the newest observation at ∼359 d post-merger. While our results are consistent with the other works using Cash statistic within uncertainty, the Bayesian analysis we performed in this work have yielded Gaussian-like parameter distributions. We also obtained the parameter uncertainties directly from their posterior probability distributions. We are able to confirm that the power-law photon index has remained constant of $\mathrm{\Gamma }\sim 1.6$ throughout the entire year-long observing period, except for the first dataset observed at $t=8.9$ d when $\mathrm{\Gamma }=1.04\pm 0.44$ is marginally harder. We also found that the unabsorbed X-ray flux peaked at $t\sim 155$ d, temporally consistent with the X-ray flare model suggested recently by Piro et al. (2019). The X-ray flux has been fading since ∼160 days after the merger and has returned to the level as first discovered after one year. Our result shows that the X-ray spectrum of GW170817/GRB170817A is well-described by a simple power-law originated from non-thermal slow-cooling synchrotron radiation.

首次，我们提出了由钱德拉X射线天文台观测到的GW170817 / GRB17017A的X射线余辉数据集的贝叶斯时间分辨光谱研究。这些数据包括来自于$Ť〜9$d至合并后约359 d的最新观测值。尽管我们的结果与不确定性下使用Cash统计量的其他工作一致，但是我们在这项工作中进行的贝叶斯分析得出了类似高斯的参数分布。我们还直接从其后验概率分布中获得了参数不确定性。我们能够确认幂律光子指数保持恒定$\mathrm{\Gamma }〜1.6$ 在整个一年的观察期内，除了在 $Ť=8.9$ d什么时候 $\mathrm{\Gamma }=1.04\pm 0.44$有点困难。我们还发现未吸收的X射线通量在$Ť〜155$d，时间上与Piro等人最近提出的X射线耀斑模型一致。（2019）。自合并后约160天以来，X射线通量一直在逐渐消失，并回到一年后首次发现的水平。我们的结果表明，GW170817 / GRB170817A的X射线光谱通过源自非热慢冷却同步加速器辐射的简单幂律很好地描述了。