标题： 伽马射线暴X射线耀发的内冲击模型研究 显示英文标题

标题： Modeling Gamma-Ray Burst X-Ray Flares within the Internal Shock Model

摘要： 对于超过400个费米伽马射线暴的X射线余辉光变曲线已经收集完成，其中将近一半的光变曲线上叠加有X射线耀发。证据表明伽马射线暴的瞬时辐射和X射线耀发具有共同的起源，并且至少一些耀发只能通过长时间的中心引擎活动来解释。我们开发了一个壳模型代码来探讨在内部冲击模型框架下如何产生X射线耀发。该壳模型从一个中心引擎随机生成伽马射线暴爆炸，并跟踪这些壳层如何碰撞、合并和扩散，从而产生瞬时辐射和X射线耀发。我们特别关注中心引擎活动的时间历史、内部冲击以及观测到的耀发，但并未详细计算冲击动力学和辐射过程。使用经验Ep-Eiso（阿马蒂）关系，并假设每个碰撞具有Band函数谱和经验耀发时间轮廓，我们计算了任意中心引擎活动下的伽马射线（费米/GBM带宽）和X射线（费米/GBM带宽）光变曲线，并将模型结果与观测数据进行比较。我们展示了观测到的X射线耀发现象可以在内部冲击模型中得到解释。然后，耀发的数量、宽度和发生时间被用来诊断中心引擎活动，对喷出壳层的能量、喷出时间、宽度和数量施加限制。我们发现观测到的X射线耀发时间历史通常反映了中心引擎的时间历史，在瞬时辐射阶段之后多次重新激活，能量逐渐减少... 显示英文摘要

摘要： X-ray afterglow light curves have been collected for over 400 Swift gamma-ray bursts with nearly half of them having X-ray flares superimposed on the regular afterglow decay. Evidence suggests that gamma-ray prompt emission and X-ray flares share a common origin and that at least some flares can only be explained by long-lasting central engine activity. We have developed a shell model code to address the question of how X-ray flares are produced within the framework of the internal shock model. The shell model creates randomized GRB explosions from a central engine with multiple shells and follows those shells as they collide, merge and spread, producing prompt emission and X-ray flares. We pay special attention to the time history of central engine activity, internal shocks, and observed flares, but do not calculate the shock dynamics and radiation processes in detail. Using the empirical E_p - E_iso (Amati) relation with an assumed Band function spectrum for each collision and an empirical flare temporal profile, we calculate the gamma-ray (Swift/BAT band) and X-ray (Swift/XRT band) lightcurves for arbitrary central engine activity and compare the model results with the observational data. We show that the observed X-ray flare phenomenology can be explained within the internal shock model. The number, width and occurring time of flares are then used to diagnose the central engine activity, putting constraints on the energy, ejection time, width and number of ejected shells. We find that the observed X-ray flare time history generally reflects the time history of the central engine, which reactivates multiple times after the prompt emission phase with progressively reduced energy...