伽马射线暴喷流能量分布暗示随宇宙时间演化的准通用弱磁化喷流
The Gamma-ray Burst Jet Energy Distribution Suggests A Quasi-universal, Weakly Magnetized Jet Evolving Over Cosmic Time
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中文总结 AI 辅助
该研究通过分析具有红移的伽马射线暴的能量分布，提出了随宇宙时间演化的准通用弱磁化喷流模型，可拟合观测分布，且与相关模拟结果一致。
中文摘要 AI 辅助
我们给出了具有红移的伽马射线暴（GRB）的观测及推导性质的分布。我们表明，各向同性能量分布跨越四个数量级，可在一个简单假设下得到合理再现：每个观测到的GRB都源自一个准通用喷流，其能量随角度变化的幂律谱指数满足$3 \lesssim \zeta \lesssim 4$，且具有大致相同的递减幂律轮廓。观测分布的弥散可仅由观测视角的变化来解释。此外，若各向同性能量归一化按一系列已发表研究提出的方式随红移演化，这种幂律喷流结构能更好地拟合各向同性能量和光度分布。该喷流相对陡峭的幂律指数与坍缩星中弱磁化喷流模拟预测的结构一致，而流体动力学喷流模拟预测的结构比我们发现的更平缓。该模型框架内预测的余辉光变曲线在与观测到的喷流断裂时间相当的时刻表现出陡化行为。
英文摘要
We present distributions of gamma-ray burst observed and inferred properties for those GRBs with redshifts. We show that the isotropic energy distribution, which spans over four orders of magnitude, can be reproduced reasonably well under a simplistic assumption that every observed GRB originates from a quasi-universal jet with roughly the same decreasing power-law profile of energy as a function of angle, with a power-law index of $ 3 \lesssim ζ\lesssim 4$. The spread in the observed distribution can be explained by the variation in observer viewing angle alone. Furthermore, this power-law jet structure provides an even better fit to both the isotropic energy and luminosity distributions if the isotropic energy normalization evolves as a function of redshift in a manner that has been suggested by a range of previously published studies. The relatively steep power-law index of this jet is consistent with the structure predicted by simulations of weakly magnetized jets in collapsars, whereas simulations of hydrodynamic jets predict a structure shallower than what we find here. The predicted afterglow light curves within this model framework show steepening behavior at times commensurate with observed jet break times.
