本文關(guān)鍵詞： 伽瑪射線暴 火球激波模型 雙結(jié)構(gòu)噴流 黑洞 磁場 BZ機(jī)制 BP機(jī)制　出處：《華中科技大學(xué)》2011年碩士論文　論文類型：學(xué)位論文

【摘要】：伽瑪射線暴（Gamma-ray Bursts, GRBs，簡稱伽瑪暴）是迄今為止人們觀測到的最劇烈的高能天體物理現(xiàn)象，其劇烈程度可能僅次于宇宙大爆炸。自從20世紀(jì)60年代被發(fā)現(xiàn)以來，伽瑪射線暴就以其短時(shí)標(biāo)、高能量、遠(yuǎn)距離、復(fù)雜光變和譜態(tài)等顯著特征而引起人們的廣泛關(guān)注。半個(gè)世紀(jì)以來，伽瑪射線暴研究領(lǐng)域在觀測和理論兩個(gè)方面都取得了許多令人矚目的成就，但仍然有許多新老問題有待解決，比如前身星問題、中心引擎噴流的產(chǎn)生和加速機(jī)制，噴流的物質(zhì)組分和結(jié)構(gòu)等等。本文主要介紹了伽瑪射線暴的觀測進(jìn)展和標(biāo)準(zhǔn)的火球激波模型，提出了一個(gè)建立在Blandford-Znajek機(jī)制和Blandford-Payne機(jī)制共存基礎(chǔ)上的磁驅(qū)動(dòng)雙結(jié)構(gòu)噴流模型。 本文首先對伽瑪射線暴的觀測進(jìn)展進(jìn)行了介紹�；仡櫫烁鱾�(gè)歷史時(shí)期主要的觀測衛(wèi)星在伽瑪射線暴觀測方面取得的重要發(fā)現(xiàn)，對伽瑪射線暴的時(shí)變特征、譜形特征、伽瑪暴的分類以及根據(jù)觀測數(shù)據(jù)統(tǒng)計(jì)得到的一些經(jīng)驗(yàn)關(guān)系進(jìn)行了概括。 其次，本文對伽瑪射線暴的標(biāo)準(zhǔn)模型——火球激波模型——進(jìn)行了比較詳細(xì)的介紹。詳細(xì)介紹了火球的概念、火球演化的動(dòng)力學(xué)過程和激波輻射理論，最終給出一個(gè)用來解釋伽瑪射線暴瞬時(shí)輻射和余輝輻射的光變曲線和譜形特征的標(biāo)準(zhǔn)火球激波模型的較為清晰的輪廓。 然后，本文對伽瑪射線暴中心引擎噴流的磁驅(qū)動(dòng)機(jī)制——主要是Blandford-Znjek和Blandford-Payne機(jī)制——進(jìn)行了簡要介紹，繼而對建立在BZ機(jī)制和BP機(jī)制共存基礎(chǔ)上雙結(jié)構(gòu)噴流模型做了初步的定量計(jì)算。在該模型中，中心噴流由Kerr黑洞的BZ機(jī)制驅(qū)動(dòng)，其噴流物質(zhì)來自于吸積盤內(nèi)區(qū)，外圍噴流由發(fā)生在吸積盤上的BP機(jī)制驅(qū)動(dòng)。在假定大尺度磁場位形和盤物質(zhì)吸積率隨盤半徑分布函數(shù)的基礎(chǔ)上，本文推導(dǎo)了磁驅(qū)動(dòng)雙成分噴流的內(nèi)外Lorentz因子的解析計(jì)算公式，，其中外圍噴流（由BP機(jī)制驅(qū)動(dòng)）的Lorentz因子取決于中心黑洞的自轉(zhuǎn)、磁場位形以及盤風(fēng)的強(qiáng)弱，中心噴流（由BZ機(jī)制驅(qū)動(dòng)）的Lorentz因子取決于黑洞的自轉(zhuǎn)以及盤內(nèi)區(qū)物質(zhì)進(jìn)入中心噴流的比例。本文發(fā)現(xiàn)BZ噴流的Lorentz因子一般要比BP噴流的Lorentz因子大得多，這意味著BZ機(jī)制和BP機(jī)制可以做為雙結(jié)構(gòu)噴流的十分自然的起源。另外，通過對三個(gè)伽瑪暴和三個(gè)活動(dòng)星系核的雙結(jié)構(gòu)噴流的內(nèi)外洛倫滋因子（Lorentzfactor）的擬合，本文發(fā)現(xiàn)這兩類不同尺度天體的吸積盤可能有很大的不同，具體說來，活動(dòng)星系核的吸積盤有很強(qiáng)的盤風(fēng)，而伽瑪射線暴中心引擎吸積盤的盤風(fēng)則相對較弱。 最后，對本文的主要內(nèi)容和伽瑪暴研究領(lǐng)域尚待解決的若干問題做了總結(jié)，對雙結(jié)構(gòu)噴流磁驅(qū)動(dòng)模型的進(jìn)一步細(xì)化做了展望。
[Abstract]:Gamma-ray burst (GRBs) is the most intense high-energy astrophysical phenomenon observed so far. Its intensity is probably second only to the Big Bang. Since its discovery in 1960s, gamma-ray bursts have been short-lived, high-energy, and long-range. Complex light variation and spectral state have attracted wide attention. In the past half century, many remarkable achievements have been made in both observation and theory in the field of gamma-ray bursts (GRBs). However, there are still many new and old problems to be solved, such as the predecessor star problem, the generation and acceleration mechanism of the central engine jet. This paper mainly introduces the observation progress of gamma ray bursts and the standard fireball shock wave model. A magnetically driven dual-structure jet model based on the coexistence of Blandford-Znajek mechanism and Blandford-Payne mechanism is proposed. In this paper, the observation progress of gamma-ray bursts is introduced, and the important findings made by the main observation satellites in each historical period are reviewed, and the time-varying characteristics of the gamma-ray bursts are also discussed. The spectral features, the classification of gamma-ray bursts and some empirical relationships based on observational data are summarized. Secondly, the standard model of gamma-ray bursts, the fireball shock model, is introduced in detail. The concept of fireball, the dynamic process of fireball evolution and the theory of shock radiation are introduced in detail. Finally, a clear outline of the standard fireball shock wave model, which is used to explain the phototropic curves and spectral characteristics of the instantaneous and afterglow radiation of gamma ray bursts, is given. And... In this paper, the magnetic driving mechanism of the GRB center engine jet, mainly the Blandford-Znjek and Blandford-Payne mechanisms, is briefly introduced. Then, the dual structure jet model based on the coexistence of BZ mechanism and BP machine is calculated. In this model, the central jet is driven by the BZ mechanism of Kerr black hole. The jet material comes from the inner area of the accretion disk, and the external jet is driven by BP machine which occurs on the accretion disk. On the basis of the assumption of the large scale magnetic field configuration and the distribution function of the mass accretion rate with the radius of the disk. In this paper, the analytical formula for the internal and external Lorentz factor of a magnetically driven two-component jet is derived, in which the Lorentz factor of the external jet (driven by a BP machine) is determined by the rotation of the central black hole. The configuration of the magnetic field and the strength of the disk wind. Central jet (driven by BZ mechanism). The Lorentz factor of BZ is determined by the rotation of the black hole and the ratio of the mass in the disk to the central jet. It is found that the Lorentz factor of the BZ jet is generally higher than that of the Lorentz factor of the BP jet. Son is much bigger. This means that BZ mechanism and BP machine system can be used as a very natural origin of dual-structure jet. The internal and external LorentzFactor of three gamma bursts and three active galactic nuclei were fitted. In this paper, we find that the accretion disks of these two kinds of objects with different scales may be very different. Specifically, the accretion disks of the active galactic nuclei have very strong disk winds, while the disk winds of the accretion disks of the center engine of the gamma ray bursts are relatively weak. Finally, the main contents of this paper and some problems that remain to be solved in the field of gamma-ray bursts are summarized, and the further refinement of the dual-structure jet magnetic drive model is prospected.
【學(xué)位授予單位】：華中科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2011
【分類號】：P172.3

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本文編號：1476316