The apparent size of gamma‐ray burst afterglows as a test of the fireball model
The apparent size of gamma‐ray burst afterglows as a test of the fireball model
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DOI：
10.1111/j.1365-2966.2004.08247.x
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发表时间：
2004-06
影响因子：
4.8
通讯作者：
Y. Oren;E. Nakar;T. Piran
中科院分区：
文献类型：
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作者：
Y. Oren;E. Nakar;T. Piran
Taylor等人最近报道了对伽玛射线暴（GRB）余辉表观大小的首次直接测量。在这里，我们将这些观测结果与火球模型的预测相对照。我们使用一个简单的模型来研究数值的火球的演变，并确定其表观尺寸，从早期的球形膨胀阶段通过射流突破，并进入牛顿政权。我们在均匀星际介质和大质量恒星风环境的背景下进行这些计算。我们发现，在泰勒等人进行测量时计算的表观尺寸仅弱地依赖于所选择的参数（射流张开角，能量和外部密度分布）。因此，令人放心的是，在合理的参数范围内，模型的唯一可能结果与数据非常吻合。因此，这些测量为我们提供了一个强有力的测试可能的伽玛暴模型，火球模型成功地通过。
Taylor et al. reported recently on the first direct measurement of the apparent size of a gamma-ray burst (GRB) afterglow. Here we confront these observations with the predictions of the fireball model. We use a simple model to study numerically the evolution of the fireball and determine its apparent size, starting at the early spherical expansion phase through the jet break and into the Newtonian regime. We perform these calculations on the background of a uniform interstellar medium and a massive stellar wind environment. We find that the calculated apparent size at the time of the measurements taken by Taylor et al. depends only weakly on the chosen parameters (the jet opening angle, the energy and the external density profile). Thus it is reassuring that the only possible outcome of the model, within the plausible range of parameters, agrees very well with the data. These measurements therefore present us with a strong test of possible GRB models, which the fireball model passes successfully.