标题： 伽马射线暴GRB 060218余辉的解释与启示 显示英文标题

标题： The Interpretation and Implication of the Afterglow of GRB 060218

摘要： 编号为060216的伽马射线暴（GRB）伴随的超新星SN 2006aj是一个持续时间极长、强度较弱且非常软的伽马射线暴。 它在许多方面都显得与众不同。 我们在这里表明，编号为060218的伽马射线暴的X射线、紫外/光学以及射电余辉必须归因于来自不同辐射区域的不同物理过程。 在这次爆发的余辉中存在几个成分，只有射电余辉可以用常见的外部冲击模型来解释。 从射电数据中我们推断出，爆炸波的动能为$\sim 10^{50}$尔格，并且爆炸环境中的物质表现出常数而非风状分布。 到第22天仍未出现“喷流断裂”，这表明喷流是宽广的$\theta_j >1$。 尽管晚期的X射线余辉以正常速率衰减，但由于其非常陡峭的能谱，它不可能是由外部冲击产生的。 此外，由此推测出的动能会产生过多的射电波。 我们认为，这个X射线余辉可能与中心引擎的持续活动有关，在塌缩星情景下，这种活动可能是由于吸积物质回坠引起的。 “中心引擎余辉”在低亮度伽马射线暴中可能很常见，因为这些伽马射线暴的爆炸波动能较小，外部冲击不会主导这一成分。 这类低亮度伽马射线暴可能非常普遍，但由于只能从短距离内检测到它们，因此很少被记录下来。 显示英文摘要

摘要： The nearby GRB 060216/SN 2006aj was an extremely long, weak and very soft GRB. It was peculiar in many aspects. We show here that the X-ray, ultraviolet/optical and radio afterglow of GRB 060218 have to be attributed to different physical processes arising from different emission regions. From the several components in this burst's afterglow only the radio afterglow can be interpreted in terms of the common external shock model. We infer from the radio that the blast wave's kinetic energy was $\sim 10^{50}$ erg and the circumburst matter had a constant rather than a wind profile. The lack of a "jet break" up to 22 days implies that the outflow was wide $\theta_j >1$. Even though the late X-ray afterglow decays normally it cannot result from an external shock because of its very steep spectrum. Furthermore, the implied kinetic energy would have produced far too much radio. We suggest that this X-ray afterglow could be attributed to a continued activity of the central engine that within the collapsar scenario could arise from fall-back accretion. "Central engine afterglow" may be common in under-luminous GRBs where the kinetic energy of the blast wave is small and the external shock does not dominate over this component. Such under-luminous GRBs might be very common but they are rarely recorded because they can be detected only from short distances.