INAF-Astronomical Observatory of Bologna, Italy.
Sci Rep. 2011;1:91. doi: 10.1038/srep00091. Epub 2011 Sep 14.
Prompt γ-ray emissions from gamma-ray bursts (GRBs) exhibit a vast range of extremely complex temporal structures with a typical variability time-scale significantly short - as fast as milliseconds. This work aims to investigate the apparent randomness of the GRB time profiles making extensive use of nonlinear techniques combining the advanced spectral method of the Singular Spectrum Analysis (SSA) with the classical tools provided by the Chaos Theory. Despite their morphological complexity, we detect evidence of a non stochastic short-term variability during the overall burst duration - seemingly consistent with a chaotic behavior. The phase space portrait of such variability shows the existence of a well-defined strange attractor underlying the erratic prompt emission structures. This scenario can shed new light on the ultra-relativistic processes believed to take place in GRB explosions and usually associated with the birth of a fast-spinning magnetar or accretion of matter onto a newly formed black hole.
伽马射线暴（GRB）的 prompt γ 射线发射表现出极其复杂的时间结构，其典型的可变性时间尺度非常短——快至毫秒级。这项工作旨在通过结合奇异谱分析（SSA）的先进谱方法和混沌理论提供的经典工具，利用非线性技术广泛研究 GRB 时间曲线的明显随机性。尽管它们的形态复杂，但我们在整个爆发期间检测到了短期非随机可变性的证据——似乎与混沌行为一致。这种可变性的相空间描绘显示出存在一个明确的奇异吸引子，这是不规则的 prompt 发射结构的基础。这种情况可以为人们相信在 GRB 爆炸中发生的超相对论过程提供新的视角，这些过程通常与快速旋转的磁星的诞生或新形成的黑洞上物质的吸积有关。
