發(fā)布時(shí)間：2018-06-09 00:42

  本文選題：脈沖星 + 星際折射式閃爍�。� 參考：《華中師范大學(xué)》2011年碩士論文

【摘要】：脈沖星星際閃爍的觀測(cè)研究領(lǐng)域一直很活躍,原因可能主要是對(duì)脈沖星的研究具有實(shí)質(zhì)性的意義。脈沖星平均脈沖輪廓的特點(diǎn)揭示了發(fā)生在中子星磁層中的輻射過(guò)程；長(zhǎng)期流量密度的變化則證實(shí)了星際介質(zhì)電子密度漲落譜和散射強(qiáng)度等特性。本論文第一章簡(jiǎn)單地介紹了脈沖星的一些背景知識(shí)。在第二章里主要概述了脈沖星星際閃爍方面的理論模型和最新進(jìn)展。而在第三章詳細(xì)講述了由兩種成分所構(gòu)成的星際閃爍模型。 由于脈沖星輻射流量存在長(zhǎng)期變化的特性曾引起天文學(xué)家關(guān)注。早期人們認(rèn)為這種流量變化是脈沖星本身的內(nèi)稟變化,最近則比較傾向于認(rèn)為是星際介質(zhì)折射引起的閃爍現(xiàn)象。本論文重點(diǎn)講述了對(duì)折射式閃爍的一種嚴(yán)謹(jǐn)?shù)奶幚矸椒?這種折射式閃爍是在Kolmogorov密度譜形式下由兩種成分的星際散射介質(zhì)組成。假定這兩種成分的星際散射介質(zhì)是由薄屏星際介質(zhì)和擴(kuò)散星際介質(zhì)組成。我們考慮到薄屏的散射集中在一個(gè)薄層上且以δ函數(shù)分布,而無(wú)規(guī)則擴(kuò)散介質(zhì)的密度滿足高斯分布。我們研究并詳細(xì)闡述了在散射分布里與這兩種成分的星際介質(zhì)幾何學(xué)相對(duì)應(yīng)的流量密度結(jié)構(gòu)函數(shù)方程,并將結(jié)果與觀測(cè)進(jìn)行了比較。我們推斷出對(duì)于觀測(cè)到的流量密度變化由兩種成分組成的星際散射的折射式閃爍確實(shí)比單個(gè)擴(kuò)散介質(zhì)模型能給出一個(gè)更滿意的解釋。折射式閃爍的起伏對(duì)沿著視線方向上的散射物質(zhì)的分布非常敏感,結(jié)構(gòu)函數(shù)的斜率對(duì)薄屏位置非常敏感而對(duì)薄屏介質(zhì)的散射強(qiáng)度來(lái)說(shuō)相對(duì)不敏感。 本論文主要利用兩種成分的星際散射介質(zhì)模型,分別對(duì)脈沖星PSR B2111+46以及PSR B0136+57進(jìn)行了流量密度的計(jì)算,并與觀測(cè)結(jié)果進(jìn)行了比較,結(jié)果表明這種介質(zhì)是由嵌入在星際介質(zhì)中等離子體湍流的非連續(xù)分布組成。脈沖星PSRB2111+46和PSR B0136+57用兩種成分的星際散射介質(zhì)模型來(lái)擬合,我們發(fā)現(xiàn)在沿視線方向上密度無(wú)規(guī)則的分布遵守Kolmogorov冪律譜的形式,從擬合結(jié)果來(lái)看與觀測(cè)符合的很好,而且與S2000結(jié)論非常一致。
[Abstract]:The observation and study of pulsar interstellar scintillation has been active for a long time, which may be mainly due to the substantial significance of the study of pulsars. The characteristics of the average pulse profile of pulsars reveal the radiation process occurring in the magnetosphere of neutron stars, and the variation of long-term flux density confirms the characteristics of electron density fluctuation spectrum and scattering intensity in interstellar media. In the first chapter of this thesis, we briefly introduce some background knowledge of pulsars. In the second chapter, the theoretical model and recent progress of pulsar interstellar scintillation are summarized. In the third chapter, the interstellar scintillation model composed of two components is described in detail. It is considered that this flow rate change is an intrinsic change of pulsar itself, but recently it tends to be considered as a flicker caused by refraction of interstellar medium. This paper focuses on a rigorous approach to refraction scintillation, which is composed of two interstellar scattering media in the form of Kolmogorov density spectrum. It is assumed that the interstellar scattering media of these two components is composed of a thin screen interstellar medium and a diffusive interstellar medium. We consider that the scattering of the thin screen is concentrated on a thin layer and distributes as a 未 function, while the density of the irregular diffusion medium satisfies the Gao Si distribution. The flow density structure function equation corresponding to the geometry of the interstellar media in the scattering distribution is studied and detailed, and the results are compared with the observations. We infer that the refraction scintillation of interstellar scattering consisting of two components is a more satisfactory explanation than a single diffusion medium model. The undulation of refraction scintillation is very sensitive to the distribution of scattered matter along the line of sight. The slope of the structure function is very sensitive to the position of the thin screen and relatively insensitive to the scattering intensity of the thin screen medium. The flow density of pulsars PSR B211146 and PSR B013657 are calculated and compared with the observed results. The results show that this medium is composed of discontinuous distributions of plasma turbulence embedded in interstellar media. The pulsars PSRB211146 and PSR B013657 are fitted with interstellar scattering media models with two components. We find that the irregular distribution of density along the line of sight follows the form of Kolmogorov power law spectrum. The fitting results are in good agreement with the observations. And it is very consistent with the conclusion of S2000.
【學(xué)位授予單位】：華中師范大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2011
【分類號(hào)】：P145.6

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本文編號(hào)：1997986