本文關(guān)鍵詞：伽馬暴X射線余輝研究與Fermi LAT未證認(rèn)源的統(tǒng)計分類　出處：《華中師范大學(xué)》2013年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 伽馬射線暴 星風(fēng) 費米伽馬射線源

【摘要】：本文的研究內(nèi)容屬于伽馬射線天文學(xué)的范疇。近年來,隨著伽馬射線空間和地面望遠鏡的更新升級以及與其它多波段觀測的緊密結(jié)合,伽馬射線天文學(xué)取得了極大發(fā)展,其研究領(lǐng)域也被大大拓寬。本文的研究主要包括兩個部分,一是對伽馬暴X射線余輝的理論研究,二是對一些未證認(rèn)的Fermi伽馬射線穩(wěn)態(tài)源的統(tǒng)計分類。 伽馬暴是伽馬射線天文學(xué)研究的主要對象之一。自1967年發(fā)現(xiàn)至今,經(jīng)過數(shù)十年的研究人們對伽馬暴的認(rèn)識已較為深入。但是,伽馬暴的中心能源問題仍然是一個未解之謎。近年來,Swift衛(wèi)星觀測到伽馬暴X射線余輝新特征(主要包括早期余輝的緩慢衰減和X射線耀發(fā)現(xiàn)象)為人們了解伽馬暴的中心能源機制提供了重要線索。在標(biāo)準(zhǔn)外激波余輝模型下,這些X射線余輝新特征無法得到有效解釋。因此,本文第一個研究工作將主要針對這一問題。為了有效解釋X射線余輝的早期變平現(xiàn)象,一般認(rèn)為伽馬暴的中心致密天體很可能是一顆高速旋轉(zhuǎn)的磁星,它可能在很長一段時間內(nèi)為外激波注入能量。但是,本文認(rèn)為,磁星能量的釋放實際上很可能是通過攜帶了大量正負(fù)電子對的Poynting流的形式。而由于磁重聯(lián)的原因,Poynting流有可能在追上伽馬暴外激波之前就已經(jīng)轉(zhuǎn)化為相對論性的正負(fù)電子對星風(fēng)。因此,星風(fēng)與伽馬暴拋射物質(zhì)相互作用產(chǎn)生的終止激波將直接導(dǎo)致很強的X射線余輝輻射,甚至完全超過伽馬暴外激波的輻射(即使有部分能量注入)。我們的數(shù)值計算結(jié)果顯示,在星風(fēng)磁化率滿足一定條件的時候,這種情況是完全可能發(fā)生的。因此,我們提出某些觀測到的伽馬暴X射線余輝有可能直接來源于磁星星風(fēng)終止激波的輻射,而不是傳統(tǒng)的外激波。一定程度上講,磁星星風(fēng)終止激波輻射可被認(rèn)為是一種內(nèi)耗散起源的余輝輻射機制。 2008年以來,Fermi衛(wèi)星的LAT探測器觀測到了大量的穩(wěn)態(tài)伽馬射線源,這些源的屬性是人們所關(guān)心的一個重要問題。Fermi合作組的證認(rèn)結(jié)果顯示,2年時間內(nèi)觀測到的1873個源中,有127個源的性質(zhì)被完全確定,另有1171個源和候選對應(yīng)體成協(xié),但是剩下575個源未找到候選對應(yīng)體。本文第二個工作就是對這575個未證認(rèn)的源進行統(tǒng)計分類研究。和具體去找候選對應(yīng)體的證認(rèn)方法不同,我們這里并不是對單個源進行分析,而是選取反映未證認(rèn)源的物理性質(zhì)的觀測量進行統(tǒng)計分析,其中包含空間分布、譜指數(shù)和光變指數(shù)。通過和已證認(rèn)的源進行比較研究,討論這575個未證認(rèn)源的可能候選對應(yīng)體。我們的統(tǒng)計分析結(jié)果顯示,這些未證認(rèn)源可能主要包括：超新星遺跡/脈沖星風(fēng)星云,蝎虎座BL天體,射電平譜類星體和其他類型的活動星系,它們的比例分別為25%,29%,41%和5%。
[Abstract]:In recent years, with the updating and upgrading of gamma ray space and ground telescopes and the close integration with other multi-band observations, the research contents of this paper belong to the field of gamma ray astronomy. Gamma-ray astronomy has made great progress, and its research field has been greatly broadened. This paper mainly includes two parts, one is the theoretical study of X-ray afterglow of gamma-ray storms. The second is the statistical classification of some unauthenticated Fermi gamma ray steady-state sources. Gamma-ray storm is one of the main objects of gamma ray astronomy. Since its discovery in 1967, after decades of research people have been more in-depth understanding of gamma storms. The central energy problem of gamma storms remains an unsolved mystery in recent years. New characteristics of X-ray afterglow of gamma-ray storms observed by Swift satellite (mainly including slow decay of early afterglow and X-ray luminescence). It provides an important clue for people to understand the central energy mechanism of gamma storms, under the standard external shock afterglow model. These new characteristics of X-ray afterglow can not be effectively explained. Therefore, the first study in this paper will focus on this problem, in order to effectively explain the early flattening phenomenon of X-ray afterglow. It is generally believed that the central dense object of the gamma storm is probably a high speed rotating magnetic star which may inject energy into the external shock waves for a long time. The release of energy from magnetic stars may in fact be in the form of a Poynting stream that carries a large number of positron and negative electron pairs, and due to magnetic reconnection. The Poynting current may have been transformed into relativistic positron to star winds before catching up with the external shock waves of gamma storms. The terminating shock produced by the interaction between the starwind and the gamma ray ejection will directly lead to strong X-ray afterglow radiation. Even beyond the radiation of the external shock wave (even if there is partial energy injection), our numerical results show that when the susceptibility of the star wind meets certain conditions. Therefore, we suggest that some observed X-ray afterglow of gamma storms may be directly derived from the radiation of the magnetic star wind terminating shock waves. To some extent, the termination of shock wave radiation by magnetic star wind can be considered as a mechanism of afterglow radiation from the origin of internal dissipation. Since 2008, a large number of steady state gamma ray sources have been observed by the LAT detector of the Fermi satellite. The attributes of these sources are an important issue of concern. The results of the Fermi team's identification show that 127 of the 1 873 sources observed in the 2-year period have been fully identified. In addition, there are 1171 source and candidate counterpart consortia. However, the remaining 575 sources have not found candidate correspondence. The second work of this paper is to study the 575 unauthenticated sources by statistical classification, which is different from the method of identifying candidates. We do not analyze a single source here, but select observations reflecting the physical properties of unauthenticated sources for statistical analysis, including spatial distribution. Spectral index and photovariation index. By comparing with the identified sources, we discuss the possible candidates for these 575 unauthenticated sources. Our statistical analysis results show that: 1. These unidentified sources may include: supernova remnants / pulsar winds nebulae, BL objects in the constellation Scorpius, emissive spectrum quasars and other types of active galaxies, which account for 25% or 29% respectively. 41% and 5.
【學(xué)位授予單位】：華中師范大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2013
【分類號】：P172.3

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本文編號：1411246