Title: Limits on Expanding Relativistic Shells from Gamma-Ray Burst Temporal Structure Show Chinese title

Title: 伽马射线暴时间结构限制了相对论壳层的膨胀

Abstract: We calculate the expected envelope of emission for relativistic shells under the assumption of local spherical symmetry. Gamma-Ray Burst envelopes rarely conform to the expected shape, which is similar to a FRED; a fast rise and exponential decay. The fast rise is determined by the time that the relativistic shell prodcues gamma rays. The decay has the form of a power law and arises from the curvature of the shell. The amount of curvature comes from the overall size of the shell so the duration of the decay phase is related to the time the shell expands before converting its energy to gamma rays. From the envelope of emission, one can estimate when the central explosion occurred and, thus, the energy required for the shell to sweep up the ISM. The energy greatly exceeds 10^{53} erg unless the bulk Lorentz factor is less than 75. This puts extreme limits on the "external" shock models. However, the alternative, "internal" shocks from a central engine, has a problem: the entire long complex time history lasting hundreds of seconds must be postulated at the central site. Show Chinese abstract

Abstract: 我们计算了相对论壳层在局部球对称假设下的发射包络。伽马射线暴的包络很少符合预期的形状，这种形状类似于FRED（快速上升和指数衰减）。快速上升由相对论壳层产生伽马射线所需的时间决定。衰减具有幂律形式，并且来源于壳层的曲率。曲率的大小取决于壳层的整体尺寸，因此衰减阶段的持续时间与壳层在将能量转化为伽马射线之前扩展的时间有关。从发射包络中，可以估算出中心爆炸发生的时间，从而估计壳层扫过星际介质所需的能量。除非壳层的本征洛伦兹因子小于75，否则能量远远超过10^{53} 尔格。这对外部冲击模型施加了极端限制。然而，另一种选择——来自中心引擎的“内部”冲击——存在问题：整个持续数百秒的复杂时间历史必须在中心位置被假定。