合并后的一千天：来自GW170817的持续X射线发射
A thousand days after the merger: continued X-ray emission from GW170817
摘要：
钱德拉X射线望远镜最近的观测继续检测到从瞬态GW 170817发射的X射线。在2020年3月9日至3月16日（合并后935 d至942 d）之间进行的96.6 ks的总曝光中，在源位置处总共测量了8个光子，对应于约5 sigma的显著性。澳大利亚望远镜紧凑阵列（ATCA）的无线电监测显示，该源已经衰减到低于我们的检测阈值（<33 uJy，3 sigma）。通过假设光谱指数β =0.585，我们得出未吸收的X射线通量约为1.4 E-15 erg/cm ^2/s，高于先前的预测，但仍与简单的结构喷流模型相一致。我们讨论了可能的情况下，可以解释X射线的长时间发射。目前的数据集出现一致的能量注入由一个长寿命的中央发动机和一个kilonova余辉的发病，所产生的子相对论合并喷出物与周围介质的相互作用。对这一来源的长期监测对于测试这些不同的模型至关重要。
英文摘要：
Recent observations with the Chandra X-ray telescope continue to detect X-ray emission from the transient GW170817. In a total exposure of 96.6 ks, performed between March 9 and March 16 2020 (935 d to 942 d after the merger), a total of 8 photons are measured at the source position, corresponding to a significance of about 5 sigma. Radio monitoring with the Australian Telescope Compact Array (ATCA) shows instead that the source has faded below our detection threshold (<33 uJy, 3 sigma). By assuming a constant spectral index beta=0.585, we derive an unabsorbed X-ray flux of approximately 1.4E-15 erg/cm^2/s, higher than earlier predictions, yet still consistent with a simple structured jet model. We discuss possible scenarios that could account for prolonged emission in X-rays. The current dataset appears consistent both with energy injection by a long-lived central engine and with the onset of a kilonova afterglow, arising from the interaction of the sub-relativistic merger ejecta with the surrounding medium. Long-term monitoring of this source will be essential to test these different models.
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