标题： 单脉冲伽马射线暴具有普遍的硬到软光谱演化特性 显示英文标题

标题： Single-Pulse Gamma-Ray Bursts have Prevalent Hard-to-Soft Spectral Evolution

摘要： 我们分析了62个亮的费米伽马射线暴的光谱演化，这些暴发具有足够大的信噪比，可以进行时间分辨的光谱分析。 我们开发了一种新的算法来检测单脉冲形态，该算法不受脉冲特定形状的影响。 相反，它只检查光变曲线中是否存在多个孤立的统计显著峰值。 此外，我们还进行了公民科学测试，以评估光变曲线形态和光谱演化。 我们发现，无论采用何种评估方法，单峰初始辐射光变曲线的暴发往往更倾向于表现出一致衰减的峰值能量，或者硬到软的光谱演化。 这与多峰暴发的行为形成对比，后者的峰值频率往往不是单调递减的。 我们在内部/外部冲击的理论框架下讨论了这一发现，并发现至少一些单脉冲暴发与特别高密度环境相关联是一致的。 显示英文摘要

摘要： We analyze the spectral evolution of 62 bright Fermi gamma-ray bursts with large enough signal to noise to allow for time resolved spectral analysis. We develop a new algorithm to test for single-pulse morphology that is insensitive to the specific shape of pulses. Instead, it only checks whether or not there are multiple, isolated, statistical significant peaks in the light curve. In addition, we carry out a citizen science test to assess light curve morphology and spectral evolution. We find that, no matter the adopted assessment method, bursts characterized by single-peaked prompt emission light curves have a greater tendency to also have a consistently decaying peak energy, or hard-to-soft spectral evolution. This contrasts the behavior of multi-peaked bursts, for which the tendency is to have a peak frequency that is not monotonically decreasing. We discuss this finding in the theoretical framework of internal/external shocks, and find it to be consistent with at least some single pulse bursts being associated with particularly high-density environments.