Superluminal motion of a relativistic jet in the neutron-star merger GW170817
Superluminal motion of a relativistic jet in the neutron-star merger GW170817
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DOI：
10.1038/s41586-018-0486-3
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发表时间：
2018-06
期刊：
影响因子：
64.8
通讯作者：
K. Mooley;K. Mooley;A. Deller;O. Gottlieb;E. Nakar;G. Hallinan;S. Bourke;D. Frail;A. Horesh;A. Corsi;K. Hotokezaka
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文献类型：
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作者：
K. Mooley;K. Mooley;A. Deller;O. Gottlieb;E. Nakar;G. Hallinan;S. Bourke;D. Frail;A. Horesh;A. Corsi;K. Hotokezaka
GW170817双中子星合并伴随着电磁波谱上的辐射，定位于距离地球约41百万秒差距的星系NGC 4993。GW170817的射电余辉和x射线余辉表现出延迟发生，，-，随着时间的推移，辐射逐渐增加（比例为0.8），在合并事件发生后约150天达到峰值，随后相对快速下降。到目前为止，已经提出了各种各样的模型来解释余辉的发射，包括一个阻塞的喷气茧…和一个成功的喷气茧，，，，，，，，-（也称为结构喷气）。然而，关于GW170817是否成功发射了相对论性喷流，观测数据仍然没有定论。在这里，我们报告使用甚长基线干涉测量的无线电观测。我们发现与GW170817相关的紧凑型射电源在合并事件发生后的75天到230天之间表现出超光速的视运动。这一测量打破了阻塞射流和成功射流茧模型之间的简并，并表明，尽管早期的射电发射是由广角流出（一个茧）提供动力，但后期的发射很可能是由一个高能的窄准直射流（开口角度小于5度）主导的，并且从大约20度的视角观察到。从GW170817中产生的准直相对论性流出物的成像为将双中子星合并和短γ射线爆发联系起来的证据增加了实质性的分量。
The binary neutron-star merger GW170817 was accompanied by radiation across the electromagnetic spectrum and localized to the galaxy NGC 4993 at a distance of about 41 megaparsecs from Earth. The radio and X-ray afterglows of GW170817 exhibited delayed onset, , –, a gradual increase in the emission with time (proportional tot0.8) to a peak about 150 days after the merger event, followed by a relatively rapid decline,. So far, various models have been proposed to explain the afterglow emission, including a choked-jet cocoon,,, –and a successful-jet cocoon,,, , , , , , –(also called a structured jet). However, the observational data have remained inconclusive,,,as to whether GW170817 launched a successful relativistic jet. Here we report radio observations using very long-baseline interferometry. We find that the compact radio source associated with GW170817 exhibits superluminal apparent motion between 75 days and 230 days after the merger event. This measurement breaks the degeneracy between the choked- and successful-jet cocoon models and indicates that, although the early-time radio emission was powered by a wide-angle outflow (a cocoon), the late-time emission was most probably dominated by an energetic and narrowly collimated jet (with an opening angle of less than five degrees) and observed from a viewing angle of about 20 degrees. The imaging of a collimated relativistic outflow emerging from GW170817 adds substantial weight to the evidence linking binary neutron-star mergers and short γ-ray bursts.