对射电脉冲星逆康普顿散射模型参数的限定
发布时间：2019-06-07 16:13
【摘要】：脉冲星是一种能够辐射出周期性脉冲信号的天体。脉冲星典型的半径约为10公里，质量大约与太阳相当，是一种典型的致密星体。脉冲星拥有极强的磁场，最高可达1014G，快速旋转的磁场能够感应出很强的电场，带电粒子在电场中被加速到相对论性，辐射出各个波段的电磁波。理论上可能的加速区模型包括真空间隙加速区模型，狭长间隙加速区模型，外间隙加速区模型和环加速区模型。不同加速区在磁层中的位置不同，出来的带电粒子产生辐射的机制也不一样。可能的辐射机制有等离子体的集体辐射，，带电粒子的曲率辐射、逆康普顿散射等。 逆康普顿散射模型主要用来解释脉冲星在射电波段的辐射特征。该模型假定在中子星表面附近形成频率约为106Hz的低频电磁波，同时磁层内部的“级联”过程会产生大量高能次级电子对。低频光子随后被相对论性次级电子散射，即发生逆康普顿散射，最终高能电子把能量传给低频光子，光子获得能量后以更高的频率出射，形成观测上得到的脉冲星射电辐射。 本文利用从欧洲脉冲星数据库（European Pulsar Network, EPN）中获取的数据，构建了一个包含15颗射电脉冲星的样本。这些脉冲星都具有累积脉冲轮廓宽度随频率升高而减小的现象。通过对样本轮廓数据进行高斯分离，获取轮廓的宽度，然后用两种不同的方法综合限定了逆康普顿散射模型中的两个关键物理参量：次级电子的初始洛伦兹因子γ0和能量损失因子ξ。结果表明样本初始洛伦兹因子的取值范围为γ04000,与真空内加速区模型的理论预言基本符合；能量损失因子20ξ 560，说明次级带电粒子的能量损失比较严重，存在某种有效的能量损失机制。 第一章和第二章主要介绍有关脉冲星的背景情况：脉冲星的发现历史，脉冲星的种类，中子星的内部结构，脉冲星的主要观测特征，理论模型背景，与脉冲星相关的前沿课题等。 第三章阐述了从EPN数据库中选择15颗脉冲星样本的标准，以及用于综合限定逆康普顿散射模型参数的两种方法。第四章介绍了处理的结果，同时对结果进行了理论上的分析和探讨。 第五章对本文做了一个简单的总结与展望。
[Abstract]:Pulsar is a kind of celestial body which can radiate periodic pulse signal. Pulsar is a typical dense star with a radius of about 10 km and a mass about the same as that of the sun. Pulsars have a very strong magnetic field, up to 1014G. The fast rotating magnetic field can induce a strong electric field. Charged particles are accelerated to relativity in the electric field and radiate electromagnetic waves in various bands. Theoretically, the possible acceleration zone models include vacuum gap acceleration zone model, narrow and long gap acceleration zone model, outer gap acceleration zone model and ring acceleration zone model. Different acceleration regions have different positions in the magnetosphere, and the radiation mechanism of charged particles is different. The possible radiation mechanisms are collective radiation of plasma, curvature radiation of charged particles, inverse Compton scattering and so on. The inverse Compton scattering model is mainly used to explain the radiation characteristics of pulsars in radio band. The model assumes that a low frequency electromagnetic wave with a frequency of about 106Hz is formed near the surface of a neutron star, and a large number of high energy secondary electron pairs will be produced in the "cascade" process inside the magnetosphere. The low frequency photons are then scattered by the relative secondary electrons, that is, the inverse Compton scattering occurs. Finally, the high energy electrons transmit the energy to the low frequency photons. After the photons obtain the energy, they emit at a higher frequency to form the observed pulsar radio radiation. Based on the data obtained from the European pulsar database (European Pulsar Network, EPN), a sample containing 15 radio pulsars is constructed in this paper. These pulsars all have the phenomenon that the cumulative pulse profile width decreases with the increase of frequency. By separating the sample outline data with Gao Si, the width of the outline is obtained. Then two key physical parameters in the inverse Compton scattering model are defined by two different methods: the initial Lorentz factor 纬 0 and the energy loss factor Zeta of the secondary electron. The results show that the initial Lorentz factor of the sample is in the range of 纬 04000, which is in good agreement with the theoretical prediction of the accelerated zone model in vacuum. The energy loss factor 20 Zeta 660 indicates that the energy loss of secondary charged particles is serious and there is an effective energy loss mechanism. The first and second chapters mainly introduce the background of pulsars: the discovery history of pulsars, the types of pulsars, the internal structure of neutron stars, the main observational characteristics of pulsars, the background of theoretical models, Frontier topics related to pulsars, etc. In chapter 3, the criteria for selecting 15 pulsar samples from EPN database and two methods for defining the parameters of inverse Compton scattering model are described. In the fourth chapter, the results are introduced, and the results are analyzed and discussed theoretically. The fifth chapter makes a simple summary and prospect of this paper.
【学位授予单位】：广州大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：P145.6
本文编号：2494921
[Abstract]:Pulsar is a kind of celestial body which can radiate periodic pulse signal. Pulsar is a typical dense star with a radius of about 10 km and a mass about the same as that of the sun. Pulsars have a very strong magnetic field, up to 1014G. The fast rotating magnetic field can induce a strong electric field. Charged particles are accelerated to relativity in the electric field and radiate electromagnetic waves in various bands. Theoretically, the possible acceleration zone models include vacuum gap acceleration zone model, narrow and long gap acceleration zone model, outer gap acceleration zone model and ring acceleration zone model. Different acceleration regions have different positions in the magnetosphere, and the radiation mechanism of charged particles is different. The possible radiation mechanisms are collective radiation of plasma, curvature radiation of charged particles, inverse Compton scattering and so on. The inverse Compton scattering model is mainly used to explain the radiation characteristics of pulsars in radio band. The model assumes that a low frequency electromagnetic wave with a frequency of about 106Hz is formed near the surface of a neutron star, and a large number of high energy secondary electron pairs will be produced in the "cascade" process inside the magnetosphere. The low frequency photons are then scattered by the relative secondary electrons, that is, the inverse Compton scattering occurs. Finally, the high energy electrons transmit the energy to the low frequency photons. After the photons obtain the energy, they emit at a higher frequency to form the observed pulsar radio radiation. Based on the data obtained from the European pulsar database (European Pulsar Network, EPN), a sample containing 15 radio pulsars is constructed in this paper. These pulsars all have the phenomenon that the cumulative pulse profile width decreases with the increase of frequency. By separating the sample outline data with Gao Si, the width of the outline is obtained. Then two key physical parameters in the inverse Compton scattering model are defined by two different methods: the initial Lorentz factor 纬 0 and the energy loss factor Zeta of the secondary electron. The results show that the initial Lorentz factor of the sample is in the range of 纬 04000, which is in good agreement with the theoretical prediction of the accelerated zone model in vacuum. The energy loss factor 20 Zeta 660 indicates that the energy loss of secondary charged particles is serious and there is an effective energy loss mechanism. The first and second chapters mainly introduce the background of pulsars: the discovery history of pulsars, the types of pulsars, the internal structure of neutron stars, the main observational characteristics of pulsars, the background of theoretical models, Frontier topics related to pulsars, etc. In chapter 3, the criteria for selecting 15 pulsar samples from EPN database and two methods for defining the parameters of inverse Compton scattering model are described. In the fourth chapter, the results are introduced, and the results are analyzed and discussed theoretically. The fifth chapter makes a simple summary and prospect of this paper.
【学位授予单位】：广州大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：P145.6
【参考文献】
相关期刊论文 前2条
1 ;An Analysis of Average Pulsar Profiles and A Study of the ρ-P relation of Pulsars[J];Chinese Journal of Astronomy and Astrophysics;2003年05期
2 徐守喜;王洪光;陈建玲;刘怡;徐仁新;乔国俊;;脉冲星辐射区结构研究[J];天文学进展;2007年04期
本文编号：2494921
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