论文标题
中子恒星合并中的茧冷却排放
Cocoon cooling emission in neutron star mergers
论文作者
论文摘要
在引力波事件GW170817中，电磁（EM）观察之前有一个$ \ sim 10 $小时的间隙，而无需检测到茧。茧由\ textit {short}伽马射线爆发（\ textit {s} grb）喷气飞机通过中子星（ns）合并的弹射器传播，茧的一部分以$ 20^{\ circ} $ 30^$ 30^{\ circ}的开头逃脱了弹出。在这里，我们对茧进行建模并计算其EM发射。我们的2D流体动力模拟表明，在逃脱的茧的每个相对论和非友善的部分中，进入同源膨胀后的密度和能量分布都具有幂律函数。为这些特征进行建模，我们通过分析计算冷却排放。我们发现，茧在早期（10---10 $^{3} $ s）的R-Process Kilonova/Macronova均超过了紫外乐队的峰值。 Cocoon的光球的相对论速度可以用Swift，Ultrasat和LSST等仪器来测量。我们还暗示，包括失败的喷气机在内的充满活力的茧可以被检测为X射线闪光灯。我们的模型阐明了物理和参数依赖性，涵盖了多种信用工区的各种中央引擎和NS合并的弹射器和\ textit {s} grbs。
In the gravitational wave event GW170817, there was a $\sim 10$ hours gap before electromagnetic (EM) observations, without detection of the cocoon. The cocoon is heated by a \textit{short} gamma-ray burst (\textit{s}GRB) jet propagating through the ejecta of a Neutron Star (NS) merger, and a part of the cocoon escapes the ejecta with an opening angle of $20^{\circ}$--$30^{\circ}$. Here we model the cocoon and calculate its EM emission. Our 2D hydrodynamic simulations suggest that the density and energy distributions, after entering homologous expansion, are well-fitted with power-law functions, in each of the relativistic and non-relativistic parts of the escaped cocoon. Modeling these features, we calculate the cooling emission analytically. We find that the cocoon outshines the r-process kilonova/macronova at early times (10--10$^{3}$ s), peaking at UV bands. The relativistic velocity of the cocoon's photosphere is measurable with instruments such as Swift, ULTRASAT and LSST. We also imply that energetic cocoons, including failed jets, might be detected as X-ray flashes. Our model clarifies the physics and parameter dependence, covering a wide variety of central engines and ejecta of NS mergers and \textit{s}GRBs in the multi-messenger era.
