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arXiv 1102.1424astro-ph.HE
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长伽马射线暴瞬发辐射的光谱演化:静电加速和绝热膨胀

Spectral evolution of long Gamma Ray Burst prompt emission: electrostatic acceleration and adiabatic expansion

F. Massaro, J. E. Grindlay

摘要:

尽管伽马射线暴(GRB)瞬发辐射的光变曲线变化很大,但它们的光谱能量分布一般是弯曲的,并且有宽的峰值。特别地,当SED峰高S_p随其峰值能量E_p的减小而减小时,它们的光谱演化可以用硬度-强度相关来描述。我们提出了一个基于静电加速的加速方案,解释了~ 0.25MeV处的Ep分布峰值.我们表明,在长的伽玛射线暴光变曲线的各个脉冲的衰减阶段,绝热膨胀损失可能占主导地位的同步辐射冷却效果。由于绝热膨胀引起的能量损失也可以用来描述在它们的衰变阶段期间观察到的光谱演化。我们的方案预测的光谱演化是一致的,在单脉冲的长BATSE伽玛暴的观察。

英文摘要:

Despite the great variation in the light curves of Gamma Ray Burst (GRB) prompt emission, their spectral energy distribution is generally curved and broadly peaked. In particular, their spectral evolution is well described by the hardness-intensity correlation during a single pulse decay phase, when the SED peak height S_p decreases as its peak energy E_p decreases. We propose an acceleration scenario, based on electrostatic acceleration, to interpret the E_p distribution peak at ~ 0.25 MeV. We show that during the decay phase of individual pulses in the long GRB light curve, the adiabatic expansion losses likely dominate the synchrotron cooling effects. The energy loss as due to adiabatic expansion can also be used to describe the spectral evolution observed during their decay phase. The spectral evolution predicted by our scenario is consistent with that observed in single pulses of long BATSE GRBs.

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