對(duì)射電脈沖星逆康普頓散射模型參數(shù)的限定
發(fā)布時(shí)間：2019-06-07 16:13
【摘要】：脈沖星是一種能夠輻射出周期性脈沖信號(hào)的天體。脈沖星典型的半徑約為10公里，質(zhì)量大約與太陽(yáng)相當(dāng)，是一種典型的致密星體。脈沖星擁有極強(qiáng)的磁場(chǎng)，最高可達(dá)1014G，快速旋轉(zhuǎn)的磁場(chǎng)能夠感應(yīng)出很強(qiáng)的電場(chǎng)，帶電粒子在電場(chǎng)中被加速到相對(duì)論性，輻射出各個(gè)波段的電磁波。理論上可能的加速區(qū)模型包括真空間隙加速區(qū)模型，狹長(zhǎng)間隙加速區(qū)模型，外間隙加速區(qū)模型和環(huán)加速區(qū)模型。不同加速區(qū)在磁層中的位置不同，出來(lái)的帶電粒子產(chǎn)生輻射的機(jī)制也不一樣。可能的輻射機(jī)制有等離子體的集體輻射，，帶電粒子的曲率輻射、逆康普頓散射等。 逆康普頓散射模型主要用來(lái)解釋脈沖星在射電波段的輻射特征。該模型假定在中子星表面附近形成頻率約為106Hz的低頻電磁波，同時(shí)磁層內(nèi)部的“級(jí)聯(lián)”過(guò)程會(huì)產(chǎn)生大量高能次級(jí)電子對(duì)。低頻光子隨后被相對(duì)論性次級(jí)電子散射，即發(fā)生逆康普頓散射，最終高能電子把能量傳給低頻光子，光子獲得能量后以更高的頻率出射，形成觀測(cè)上得到的脈沖星射電輻射。 本文利用從歐洲脈沖星數(shù)據(jù)庫(kù)（European Pulsar Network, EPN）中獲取的數(shù)據(jù)，構(gòu)建了一個(gè)包含15顆射電脈沖星的樣本。這些脈沖星都具有累積脈沖輪廓寬度隨頻率升高而減小的現(xiàn)象。通過(guò)對(duì)樣本輪廓數(shù)據(jù)進(jìn)行高斯分離，獲取輪廓的寬度，然后用兩種不同的方法綜合限定了逆康普頓散射模型中的兩個(gè)關(guān)鍵物理參量：次級(jí)電子的初始洛倫茲因子γ0和能量損失因子ξ。結(jié)果表明樣本初始洛倫茲因子的取值范圍為γ04000,與真空內(nèi)加速區(qū)模型的理論預(yù)言基本符合；能量損失因子20ξ 560，說(shuō)明次級(jí)帶電粒子的能量損失比較嚴(yán)重，存在某種有效的能量損失機(jī)制。 第一章和第二章主要介紹有關(guān)脈沖星的背景情況：脈沖星的發(fā)現(xiàn)歷史，脈沖星的種類，中子星的內(nèi)部結(jié)構(gòu)，脈沖星的主要觀測(cè)特征，理論模型背景，與脈沖星相關(guān)的前沿課題等。 第三章闡述了從EPN數(shù)據(jù)庫(kù)中選擇15顆脈沖星樣本的標(biāo)準(zhǔn)，以及用于綜合限定逆康普頓散射模型參數(shù)的兩種方法。第四章介紹了處理的結(jié)果，同時(shí)對(duì)結(jié)果進(jìn)行了理論上的分析和探討。 第五章對(duì)本文做了一個(gè)簡(jiǎn)單的總結(jié)與展望。
[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 緯 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 緯 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.
【學(xué)位授予單位】：廣州大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2012
【分類號(hào)】：P145.6
本文編號(hào)：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 緯 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 緯 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.
【學(xué)位授予單位】：廣州大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2012
【分類號(hào)】：P145.6
【參考文獻(xiàn)】
相關(guān)期刊論文 前2條
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;陳建玲;劉怡;徐仁新;喬國(guó)俊;;脈沖星輻射區(qū)結(jié)構(gòu)研究[J];天文學(xué)進(jìn)展;2007年04期
本文編號(hào)：2494921
本文鏈接：http://sikaile.net/kejilunwen/tianwen/2494921.html
最近更新
教材專著
