发表机构
College of Physics Science and Technology, Hebei University; Institute of Astrophysics, Central China Normal University; Institute for Frontier in Astronomy and Astrophysics, Beijing Normal University; Department of Astronomy, Beijing Normal University（河北大学物理科学与技术学院; 华中师范大学天体物理研究所; 北京师范大学天文与天体物理前沿研究院; 北京师范大学天文学系）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过含漏斗泄漏的单区模型，发现双中子星并合后早期维恩火球的漏斗泄漏能量损失显著，或可解释短伽马射线暴延展辐射的准热成分。
AI 中文摘要
双中子星（NS）并合后幸存的新生中子星，会在抛射物仍处于光学厚阶段时，将其转动能量注入周围抛射物中。注入的能量通过正负电子对级联过程重新分布，星云成为由光子和正负电子对组成的辐射主导等离子体，其中康普顿散射主导能量交换，且散射过程中光子数守恒。本研究采用包含对产生、对湮灭、光子注入、扩散，以及特有的喷流诱导极向漏斗泄漏过程的单区模型演化该星云。对于典型参数，我们发现早期康普顿参数y远大于1，因此星云在100秒至数千秒内（具体时长取决于并合后中子星的磁场强度）保持饱和康普顿化状态，其辐射场呈现具有康普顿平衡温度的维恩谱，这类星云即所谓的维恩火球。早期康普顿温度从数十keV降至数keV，只要抛射物仍处于光学厚阶段，漏斗泄漏的能量损失就与绝热损失相当或超过绝热损失。漏斗辐射为准热辐射，其各向等效光度远高于自转减速光度。我们提出，短伽马射线暴延展辐射中观测到的准热成分，可能源自星云火球的漏斗泄漏。
英文摘要
A newborn neutron star (NS) that survives after a binary NS merger can inject its rotational energy into the surrounding ejecta while the ejecta are still optically thick. The injected energy is redistributed by the pair cascade, and the nebula becomes a radiation-dominated plasma composed of photons and e^+- pairs. Compton scattering then governs the energy exchange while the photon number is conserved in scattering. This nebula is evolved with a one-zone model that includes pair creation, annihilation, photon injection, diffusion, and in particular the leakage through the jet-induced polar funnel. For typical parameters, we find that the Compton parameter y is much larger than unity at early times. The nebula therefore remains in saturated Comptonization for 100 s to a few thousand seconds, depending on the magnetic field strength of the post-merger NS. The radiation field takes a Wien spectrum with a Compton equilibrium temperature. The nebula is then a so-called Wien fireball. The Compton temperature decreases from tens of keV to a few keV at early times. As long as the ejecta are optically thick, the funnel leakage is comparable to or exceeds the adiabatic loss. The funnel emission is quasi-thermal, and its isotropic-equivalent luminosity is much higher than the spin-down luminosity. We suggest that the quasi-thermal components observed in the extended emission of short gamma-ray bursts could come from the funnel leakage of the nebula fireball.
Comments12 pages, 8 figures, submitted to ApJ
