Bimodal distribution of the autocorrelation function in gamma-ray bursts
Bimodal distribution of the autocorrelation function in gamma-ray bursts
复制标题
伽马射线暴中自相关函数的双峰分布
DOI：
10.1051/0004-6361:20034567
复制
发表时间：
2004
影响因子：
6.5
通讯作者：
L. Borgonovo
中科院分区：
文献类型：
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作者：
L. Borgonovo
伽马射线爆发（GRB）是主要在伽马射线波段观察到的零星闪光。它们是宇宙诞生以来最明亮的爆炸，也是目前检测到的最远的天文来源。自从 20 世纪 60 年代末偶然发现伽玛暴以来，伽玛暴的研究已发展成为天体物理学中最活跃的领域之一，并在许多其他科学领域产生影响。尽管进行了大量研究，但有关伽玛暴性质的许多基本问题仍未得到解答。长时间的爆发被认为是与超大质量恒星坍缩相关的超相对论外流的结果。负责发射的机制、发射器的几何形状以及所涉及的辐射过程仍然是一个研究问题。常见的多脉冲爆发显示出与其光变曲线一样复杂的光谱演化。然而，尚不清楚是什么产生了观察到的变异性。本论文提出的工作旨在为回答这些开放性问题奠定必要的基础。提出了光谱演化的表征（基于时间分辨光谱分析），它提供了对潜在发射过程的深入了解，并对当前物理模型施加了严格的约束（论文 I）。我们报告了对涵盖时间和光谱特性的广泛伽玛暴物理参数进行多变量分析的结果。经验关系被发现表明爆发光曲线的自相似特性以及与作为距离指示器的潜在用途的光度相关性（论文II）。确定任何天文现象的相关时间尺度对于理解其相关的物理过程至关重要。时间序列分析中的线性方法是研究人员的强大工具，可以深入了解所研究系统的潜在动态。这些方法首次用于伽玛暴光变曲线，校正宇宙时间膨胀效应，揭示了两类变异性。讨论了这些类别的可能起源（论文 III 和 IV）。
Gamma-ray bursts (GRBs) are sporadic flashes of light observed primarily in the gamma-ray band. Being the brightest explosions in the Universe since its birth, they are at present also the furthest astronomical sources detected. Since their serendipitous discovery in the late 1960s the study of GRBs has grown into one of the most active fields in astrophysics with ramifications in many other scientific areas.Despite intense studies many of the basic questions about the nature of GRBs remain unanswered. Long duration bursts are believed to be the result of ultra-relativistic outflows associated with the collapse of very massive stars. The mechanisms responsible for the emission, the geometry of the emitter, and the radiative processes involved are still a matter of research. Common multi-pulse bursts display a spectral evolution as complex as their light curves. However, it is unclear what produces the observed variability. The works presented in this thesis aim to build the necessary base to answer these open questions.A characterization of the spectral evolution is presented (based on time-resolved spectral analysis) that provides insight into the underlying emission processes and imposes severe constraints on current physical models (Paper I).We report the results of a multi-variate analysis on a broad range of GRB physical parameters covering temporal and spectral properties. Empirical relations were found that indicate a self-similar property in burst light curves and a luminosity correlation with potential use as a distance indicator (Paper II).Determining the relevant timescales of any astronomical phenomenon is essential to understand its associated physical processes. Linear methods in time-series analysis are powerful tools for the researcher that can provide insight into the underlying dynamics of the studied systems. For the first time these methods were used on GRB light curves correcting for cosmic time dilation effects which revealed two classes of variability. The possible origin of these classes is discussed (Papers III & IV).