伽玛暴能谱和伽玛暴宇宙学
发布时间：2019-06-12 16:51
【摘要】：本文首先简要概述了伽玛射线暴及其余辉的观测特征和理论研究现状,然后详细介绍本人在攻读硕士学位期间在伽玛暴谱能演化性质和伽玛暴宇宙学方面的研究结果。 利用Fermi卫星的多波段观测数据,我们分析了Fermi/GBM仪器所观测到的51个明亮长暴和11个短暴的时间分辨谱,并研究了同一个暴中的Ep演化行为。我们的样本中有8个单脉冲长暴,其中5个暴的谱是由硬变软,3个暴的谱是跟随流量的变化。多脉冲长暴的谱演化更加复杂。在多脉冲暴的第一个脉冲里,差不多有半数暴的谱是由硬变软,另一半的谱是跟随流量的变化。大部分晚期脉冲的谱都是跟随流量强度的变化,但也有2个暴的第二个独立脉冲是由硬变软的。统计上可以看出,由硬变软的脉冲光变一般是快上升慢下降,比跟随流量变化的脉冲更加趋向于不对称。时间分辨率取16毫秒的短暴都是谱跟随流量强度的变化。通过模拟分析,我们发现至少有部分跟随流量变化的晚期脉冲是由硬变软的脉冲相互叠加造成的。但是,一些多脉冲长暴的第一个脉冲和单脉冲暴确实存在跟随流量变化的谱演化行为,说明这种演化方式是一个独立的成分。对于有测量到红移的伽玛暴,我们分析了它们时间分辨谱的Ep-Lr,i50关系,发现该关系的斜率、弥散度都和时间积分谱的Amati/Yonetoku关系相一致。我们讨论了关于E,演化的各种辐射机制模型,包括伽玛暴的喷流进动。观测数据似乎对这些模型都提出了挑战,但它们对揭开伽玛暴瞬时辐射的本质至关重要。 伽玛暴的喷流张角θj,对红移z有一定的依赖性,高红移处的喷流张角相对较小,而低红移处的喷流张角又相对较大。这种演化特征是基于目前观测样本的统计结果。然而我们知道观测样本不可避免地要受到仪器选择效应的影响。我们利用Bootstrapping方法探讨是否能用仪器选择效应来解释喷流张角对红移的依赖性。我们考虑了各种选择效应,包括流量阂值、仪器触发效率、喷流张角刚好指向仪器视角的概率和红移的测量概率。我们的模拟结果能够很好地重现观测上的θj-z依赖性,表明这种依赖性是仪器选择效应造成的。 随着探测到高红移(z4)暴的数量迅速增加,高红移处的伽玛暴爆发率已显著高于恒星形成率的预期。我们通过蒙特卡罗模拟方法,探讨了能够解释伽玛暴在高红移处具有较高爆发率的可能物理原因,物理原因可能是指光度函数的宇宙学演化。
[Abstract]:In this paper, the observational characteristics and theoretical research status of gamma ray bursts and their afterglow are briefly summarized, and then my research results on the evolution properties of gamma burst spectrum energy and gamma storm cosmology during my master's degree are introduced in detail. Using the multi-band observation data of Fermi satellite, we analyze the time-resolved spectra of 51 bright long storms and 11 short bursts observed by Fermi/GBM instruments, and study the evolution behavior of Ep in the same storm. There are eight monopulse bursts in our sample, of which 5 are soft from hard to soft, and three of them follow the flow rate. The spectral evolution of multi-pulse long bursts is more complex. In the first pulse of multi-pulse burst, almost half of the spectrum of the storm changes from hard to soft, and the other half of the spectrum follows the change of flow rate. Most of the late pulse spectra follow the change of flow intensity, but the second independent pulse of two bursts is softened from hard to soft. Statistically, it can be seen that the pulse light from hard to soft generally rises and decreases rapidly, and tends to be asymmetrical than the pulse with the change of flow rate. Short bursts with 16 milliseconds of time resolution are all spectral changes following the flow intensity. Through the simulation analysis, we find that at least part of the late pulse that follows the flow change is caused by the superposition of hard softened pulse with each other. However, the first pulse and monopulse burst of some multi-pulse long bursts do have spectral evolution behavior following the change of flow rate, which indicates that this evolution mode is an independent component. For gamma bursts with red shift, we analyze the Ep-Lr,i50 relation of their time resolution spectrum, and find that the slope and dispersion of the relation are consistent with the Amati/Yonetoku relation of time integral spectrum. We discuss various radiation mechanism models of E evolution, including the jet precession of gamma bursts. The observation data seem to challenge these models, but they are very important to unravel the nature of instantaneous radiation of gamma bursts. The jet tension angle of gamma storm is dependent on red shift z to a certain extent. The jet tension angle at high red shift is relatively small, while the jet tension angle at low red shift is relatively large. This evolution feature is based on the statistical results of the current observation samples. However, we know that the observed samples are inevitably affected by the instrument selection effect. We use Bootstrapping method to explore whether the instrument selection effect can be used to explain the dependence of jet tension angle on red shift. We consider various selection effects, including the flow threshold, the trigger efficiency of the instrument, the probability that the jet angle just points to the angle of view of the instrument and the measurement probability of the redshift. Our simulation results can well reproduce the observed thj 鈮，
本文编号：2498157
[Abstract]:In this paper, the observational characteristics and theoretical research status of gamma ray bursts and their afterglow are briefly summarized, and then my research results on the evolution properties of gamma burst spectrum energy and gamma storm cosmology during my master's degree are introduced in detail. Using the multi-band observation data of Fermi satellite, we analyze the time-resolved spectra of 51 bright long storms and 11 short bursts observed by Fermi/GBM instruments, and study the evolution behavior of Ep in the same storm. There are eight monopulse bursts in our sample, of which 5 are soft from hard to soft, and three of them follow the flow rate. The spectral evolution of multi-pulse long bursts is more complex. In the first pulse of multi-pulse burst, almost half of the spectrum of the storm changes from hard to soft, and the other half of the spectrum follows the change of flow rate. Most of the late pulse spectra follow the change of flow intensity, but the second independent pulse of two bursts is softened from hard to soft. Statistically, it can be seen that the pulse light from hard to soft generally rises and decreases rapidly, and tends to be asymmetrical than the pulse with the change of flow rate. Short bursts with 16 milliseconds of time resolution are all spectral changes following the flow intensity. Through the simulation analysis, we find that at least part of the late pulse that follows the flow change is caused by the superposition of hard softened pulse with each other. However, the first pulse and monopulse burst of some multi-pulse long bursts do have spectral evolution behavior following the change of flow rate, which indicates that this evolution mode is an independent component. For gamma bursts with red shift, we analyze the Ep-Lr,i50 relation of their time resolution spectrum, and find that the slope and dispersion of the relation are consistent with the Amati/Yonetoku relation of time integral spectrum. We discuss various radiation mechanism models of E evolution, including the jet precession of gamma bursts. The observation data seem to challenge these models, but they are very important to unravel the nature of instantaneous radiation of gamma bursts. The jet tension angle of gamma storm is dependent on red shift z to a certain extent. The jet tension angle at high red shift is relatively small, while the jet tension angle at low red shift is relatively large. This evolution feature is based on the statistical results of the current observation samples. However, we know that the observed samples are inevitably affected by the instrument selection effect. We use Bootstrapping method to explore whether the instrument selection effect can be used to explain the dependence of jet tension angle on red shift. We consider various selection effects, including the flow threshold, the trigger efficiency of the instrument, the probability that the jet angle just points to the angle of view of the instrument and the measurement probability of the redshift. Our simulation results can well reproduce the observed thj 鈮，
本文编号：2498157
本文链接：https://www.wllwen.com/kejilunwen/tianwen/2498157.html
