脉冲星流量密度变化和星际闪烁模型

发布时间：2018-06-09 00:42

本文选题：脉冲星 + 星际折射式闪烁　；参考：《华中师范大学》2011年硕士论文

【摘要】：脉冲星星际闪烁的观测研究领域一直很活跃,原因可能主要是对脉冲星的研究具有实质性的意义。脉冲星平均脉冲轮廓的特点揭示了发生在中子星磁层中的辐射过程；长期流量密度的变化则证实了星际介质电子密度涨落谱和散射强度等特性。本论文第一章简单地介绍了脉冲星的一些背景知识。在第二章里主要概述了脉冲星星际闪烁方面的理论模型和最新进展。而在第三章详细讲述了由两种成分所构成的星际闪烁模型。由于脉冲星辐射流量存在长期变化的特性曾引起天文学家关注。早期人们认为这种流量变化是脉冲星本身的内禀变化,最近则比较倾向于认为是星际介质折射引起的闪烁现象。本论文重点讲述了对折射式闪烁的一种严谨的处理方法,这种折射式闪烁是在Kolmogorov密度谱形式下由两种成分的星际散射介质组成。假定这两种成分的星际散射介质是由薄屏星际介质和扩散星际介质组成。我们考虑到薄屏的散射集中在一个薄层上且以δ函数分布,而无规则扩散介质的密度满足高斯分布。我们研究并详细阐述了在散射分布里与这两种成分的星际介质几何学相对应的流量密度结构函数方程,并将结果与观测进行了比较。我们推断出对于观测到的流量密度变化由两种成分组成的星际散射的折射式闪烁确实比单个扩散介质模型能给出一个更满意的解释。折射式闪烁的起伏对沿着视线方向上的散射物质的分布非常敏感,结构函数的斜率对薄屏位置非常敏感而对薄屏介质的散射强度来说相对不敏感。本论文主要利用两种成分的星际散射介质模型,分别对脉冲星PSR B2111+46以及PSR B0136+57进行了流量密度的计算,并与观测结果进行了比较,结果表明这种介质是由嵌入在星际介质中等离子体湍流的非连续分布组成。脉冲星PSRB2111+46和PSR B0136+57用两种成分的星际散射介质模型来拟合,我们发现在沿视线方向上密度无规则的分布遵守Kolmogorov幂律谱的形式,从拟合结果来看与观测符合的很好,而且与S2000结论非常一致。
[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.
【学位授予单位】：华中师范大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：P145.6

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