论文标题
高度离子灯笼的不透明度以及对基尔洛诺瓦早期的影响
Opacity of the highly ionized lanthanides and the effect on the early kilonova
论文作者
论文摘要
我们首次在中子星合并后的T〜小时，研究了Lanthanides（Z = 57-71）的存在（Z = 57-71）的影响。为此，我们计算选定的灯笼：ND（Z = 60），SM（Z = 62）和EU（Z = 63）的原子结构和不透明性。我们考虑到合并后几个小时，在T〜10^5 k后的第十（XI）的电离学度（XI）。使用新的不透明度，我们执行辐射转移模拟，以表明与无灯笼的弹射器相比，早期的光曲线在t〜0.1天时比（最大）四个（最大）因子变得淡淡。但是，由于不透明度在喷射的最外层的不透明度的迅速演变，光曲线受影响的周期相对较短。我们预测，对于〜100 mpc的源，富含灯笼的弹射器的紫外线亮度显示在T〜0.1天时下降至〜21-22 mag，而紫外线峰值在t〜0.2天左右，幅度为〜19 mag。现有的紫外线卫星（如Swift或即将到来的UV卫星Ultrasat）对这种KILONOVA的未来检测将对外喷射的丰度以及中子星合并中相应的核合成条件提供有用的约束。
We investigate the effect of the presence of lanthanides (Z = 57- 71) on the kilonova at t~hours after the neutron star merger for the first time. For this purpose, we calculate the atomic structures and the opacities for selected lanthanides: Nd (Z = 60), Sm (Z = 62), and Eu (Z = 63). We consider the ionization degree up to tenth (XI), applicable for the ejecta at t ~ a few hours after the merger, when the temperature is T ~ 10^5 K. We find that the opacities for the highly ionized lanthanides are exceptionally high, reaching k_exp~1000 cm^2/g for Eu, due to the highly dense energy levels. Using the new opacity, we perform radiative transfer simulations to show that the early light curves become fainter by a (maximum) factor of four, in comparison to lanthanide-free ejecta at t~0.1 day. However, the period at which the light curves are affected is relatively brief due to the rapid time evolution of the opacity in the outermost layer of the ejecta. We predict that for a source at a distance of ~100 Mpc, UV brightness for lanthanide-rich ejecta shows a drop to ~21-22 mag at t~0.1 day and the UV peaks around t~0.2 day with a magnitude of ~19 mag. Future detection of such a kilonova by the existing UV satellite like Swift or the upcoming UV satellite ULTRASAT will provide useful constraints on the abundance in the outer ejecta and the corresponding nucleosynthesis conditions in the neutron star mergers.
