伽瑪暴能譜和伽瑪暴宇宙學
發(fā)布時間：2019-06-12 16:51
【摘要】：本文首先簡要概述了伽瑪射線暴及其余輝的觀測特征和理論研究現(xiàn)狀,然后詳細介紹本人在攻讀碩士學位期間在伽瑪暴譜能演化性質(zhì)和伽瑪暴宇宙學方面的研究結(jié)果。 利用Fermi衛(wèi)星的多波段觀測數(shù)據(jù),我們分析了Fermi/GBM儀器所觀測到的51個明亮長暴和11個短暴的時間分辨譜,并研究了同一個暴中的Ep演化行為。我們的樣本中有8個單脈沖長暴,其中5個暴的譜是由硬變軟,3個暴的譜是跟隨流量的變化。多脈沖長暴的譜演化更加復雜。在多脈沖暴的第一個脈沖里,差不多有半數(shù)暴的譜是由硬變軟,另一半的譜是跟隨流量的變化。大部分晚期脈沖的譜都是跟隨流量強度的變化,但也有2個暴的第二個獨立脈沖是由硬變軟的。統(tǒng)計上可以看出,由硬變軟的脈沖光變一般是快上升慢下降,比跟隨流量變化的脈沖更加趨向于不對稱。時間分辨率取16毫秒的短暴都是譜跟隨流量強度的變化。通過模擬分析,我們發(fā)現(xiàn)至少有部分跟隨流量變化的晚期脈沖是由硬變軟的脈沖相互疊加造成的。但是,一些多脈沖長暴的第一個脈沖和單脈沖暴確實存在跟隨流量變化的譜演化行為,說明這種演化方式是一個獨立的成分。對于有測量到紅移的伽瑪暴,我們分析了它們時間分辨譜的Ep-Lr,i50關(guān)系,發(fā)現(xiàn)該關(guān)系的斜率、彌散度都和時間積分譜的Amati/Yonetoku關(guān)系相一致。我們討論了關(guān)于E,演化的各種輻射機制模型,包括伽瑪暴的噴流進動。觀測數(shù)據(jù)似乎對這些模型都提出了挑戰(zhàn),但它們對揭開伽瑪暴瞬時輻射的本質(zhì)至關(guān)重要。 伽瑪暴的噴流張角θj,對紅移z有一定的依賴性,高紅移處的噴流張角相對較小,而低紅移處的噴流張角又相對較大。這種演化特征是基于目前觀測樣本的統(tǒng)計結(jié)果。然而我們知道觀測樣本不可避免地要受到儀器選擇效應的影響。我們利用Bootstrapping方法探討是否能用儀器選擇效應來解釋噴流張角對紅移的依賴性。我們考慮了各種選擇效應,包括流量閡值、儀器觸發(fā)效率、噴流張角剛好指向儀器視角的概率和紅移的測量概率。我們的模擬結(jié)果能夠很好地重現(xiàn)觀測上的θj-z依賴性,表明這種依賴性是儀器選擇效應造成的。 隨著探測到高紅移(z4)暴的數(shù)量迅速增加,高紅移處的伽瑪暴爆發(fā)率已顯著高于恒星形成率的預期。我們通過蒙特卡羅模擬方法,探討了能夠解釋伽瑪暴在高紅移處具有較高爆發(fā)率的可能物理原因,物理原因可能是指光度函數(shù)的宇宙學演化。
[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，
本文編號：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，
本文編號：2498157
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