Early spectra of the gravitational wave source GW170817: Evolution of a neutron star merger
Early spectra of the gravitational wave source GW170817: Evolution of a neutron star merger
复制标题
DOI：
10.1126/science.aaq0186
复制
发表时间：
2017-10
期刊：
影响因子：
56.9
通讯作者：
B. Shappee;J. Simon;M. Drout;A. Piro;N. Morrell;J. Prieto;J. Prieto;D. Kasen;D. Kasen;
中科院分区：
文献类型：
--
作者：
B. Shappee;J. Simon;M. Drout;A. Piro;N. Morrell;J. Prieto;J. Prieto;D. Kasen;D. Kasen;
来自引力波事件的光子两颗中子星合并在一起会产生引力波信号，也被预测会发出电磁辐射。当引力波事件GW 170817被发现时，天文学家们急忙使用传统望远镜寻找来源（见史密斯的介绍）。Coulter等人描述了一米两半球（1 M2 H）合作如何首次定位电磁源。德劳特等人提出了1 M2 H的光学和红外亮度测量，沙皮等人报告了他们对该事件的光谱学，这与以前探测到的天文瞬态源不同。Kilpatrick等人展示了如何用一种被称为kilonova的爆炸来解释这些观察结果，这种爆炸在核反应中产生大量的重元素。《科学》，本期第1556页，第1570页，第1574页，第1583页;另见第1554页中子星星合并的光谱与其他天文瞬变不同，表明了源的快速演化。2017年8月17日，斯沃普超新星巡天2017 a（SSS 17 a）被发现是双星中子星星引力波事件GW 170817的光学对应物。我们报告了SSS 17 a从合并后11.75小时到8.5天的时间序列光谱。在观测的第一个小时里，喷出物迅速膨胀和冷却。通过对光谱进行黑体拟合，我们测量了光球从11，000 −900+3400开尔文冷却到9300−300+300开尔文，并确定光球速度约为光速的30%。SSS 17 a的光谱在1.46天后开始显示出广泛的特征，并在随后的每一天进行定性演变，具有明显的蓝色（早期）和红色（晚期）成分。晚期成分与r-过程富集中子星星喷出物的理论模型一致，而蓝色成分需要高速、不含镧系元素的物质。
Photons from a gravitational wave event Two neutron stars merging together generate a gravitational wave signal and have also been predicted to emit electromagnetic radiation. When the gravitational wave event GW170817 was detected, astronomers rushed to search for the source using conventional telescopes (see the Introduction by Smith). Coulter et al. describe how the One-Meter Two-Hemispheres (1M2H) collaboration was the first to locate the electromagnetic source. Drout et al. present the 1M2H measurements of its optical and infrared brightness, and Shappee et al. report their spectroscopy of the event, which is unlike previously detected astronomical transient sources. Kilpatrick et al. show how these observations can be explained by an explosion known as a kilonova, which produces large quantities of heavy elements in nuclear reactions. Science, this issue p. 1556, p. 1570, p. 1574, p. 1583; see also p. 1554 Spectra of a neutron star merger are unlike other astronomical transients and demonstrate rapid evolution of the source. On 17 August 2017, Swope Supernova Survey 2017a (SSS17a) was discovered as the optical counterpart of the binary neutron star gravitational wave event GW170817. We report time-series spectroscopy of SSS17a from 11.75 hours until 8.5 days after the merger. Over the first hour of observations, the ejecta rapidly expanded and cooled. Applying blackbody fits to the spectra, we measured the photosphere cooling from 11,000−900+3400 to 9300−300+300 kelvin, and determined a photospheric velocity of roughly 30% of the speed of light. The spectra of SSS17a began displaying broad features after 1.46 days and evolved qualitatively over each subsequent day, with distinct blue (early-time) and red (late-time) components. The late-time component is consistent with theoretical models of r-process–enriched neutron star ejecta, whereas the blue component requires high-velocity, lanthanide-free material.