KMS of Xinjiang Astronomical Observatory, CAS
| 脉冲星单脉冲辐射特性的观测研究 | |
| Alternative Title | An Observational Study of Single Pulse Emission Properties of Pulsars |
茹克娅·热介甫
| |
| Subtype | 博士 |
| Thesis Advisor | 王娜 |
| 2022-05-25 | |
| Degree Grantor | 中国科学院大学 |
| Place of Conferral | 北京 |
| Degree Name | 理学博士 |
| Degree Discipline | 天体物理 |
| Keyword | 脉冲星，单脉冲，脉冲消零，子脉冲漂移，偏振 |
| Abstract | 射电脉冲星单脉冲的研究为理解其潜在的辐射机制提供了独特的机会。本论文主要研究射电脉冲星的单脉冲辐射特性和偏振特性。 在本文的第一章中,本论文研究简要的介绍射电脉冲星的基本性质,单脉冲的主要辐射特性,射电脉冲星的辐射机制以及其可能的理论解释,脉冲星的自转特性以及星际介质对脉冲信号传播的影响等。 本文的第二章主要介绍了 Parkes 64-m 射电望远镜,接收机,观测终端以及本论文研究所用数据。 在本文的第三章中,通过分析 2014 年 4 月至 10 月期间使用 Parkes 64-m 射电望远镜在中心频率 1369 MHz 进行的五次单脉冲观测,本研究对 PSR J1727−2739的单脉冲辐射特性进行了研究,其脉冲积分轮廓由两个成分组成。从总长约为 6.1 个小时的观测数据中,去除射频干扰(radio frequency interference,简称 RFI) 之后,总共得到了 16718 个单脉冲。根据之前的研究,PSR J1727−2739 同时显示脉冲消零以及子脉冲漂移现象。本研究估计这颗源的消零比为 66%±1.4%,这与先前研究公布的结果是相一致的。在前人对前导成分子脉冲漂移的研究基础上,观测到这颗源的后随成分也显示出漂移特性。观测到有两种不同的漂移模式,它们的漂移带的垂直分离 P3 与早期研究一致。发现两个轮廓成分在一定的漂移模式下具有相同的漂移周期 P3 ,然而测量得到的漂移水平间隔 P2 大相同。PSRJ1727−2739 是在不同漂移模式之间显示出漂移周期性变化以及在给定的漂移模式下各成分之间的漂移速率变化的一颗脉冲星。随着漂移模式的变化而表现出消零的脉冲星,如 PSR J1727−2739,为研究这些现象的物理机制提供了一个独特的机会。 本文的第四章中,分析研究了使用 Parkes 64-m 射电望远镜分别在 732 和 3100 MHz 在两段时间对 PSR B0950+08 进行的同时单脉冲观测。同时分析了另一个 1369 MHz 非同时观测的数据,以比较这颗脉冲星在不同频率的偏振特性。先前研究报道的间歇脉冲和主脉冲之间的低水平桥辐射在 732 MHz 观测显著存在。然而,在更高的频率,桥辐射变得非常微弱或无法检测。对同时观测的互相关分析结果表明,单脉冲的总强度是高度相关的,这意味着两个不同频率的辐射机制是相同的。本研究证实了这颗脉冲星中的偏振位置角(polarization angle,简称 PA)跳变是非正交的,这可能是由两个非正交偏振模式的重叠辐射造成的,并且不同偏振模式之间的分离与频率有关。本研究发现在所有三个不同频率,占主导的偏振模式明显与圆偏振的负值有关,但弱模式的关联性似乎不清楚。 |
| Other Abstract | Single pulse studies of the radio pulsars provide the unique opportunity to understand the underlying emission mechanism. In this thesis, we mainly investigate thesingle pulse emission properties and the polarization properties of radio pulsars. In the first chapter of this thesis, we briefly introduce the basic properties of radio pulsars, the main emission properties of single pulses, the emission mechanism of radio pulsars and its possible theoretical explanations, the rotation characteristics of pulsars and the influence of interstellar medium on pulse signal propagation. The second chapter mainly introduces the Parkes 64-m radio telescope, the receiver, the backend system and the observational data used in this paper. In the third chapter of this thesis, by analysing five single pulse observations that were made using the Parkes 64-m radio telescope with a central frequency of 1369 MHz between 2014 April and October, we have carried out a study of single pulse emission properties of PSR J1727−2739, whose mean pulse profile has two main components. The total observation time is about 6.1 hours which contains 16718 pulses after removal of radio frequency interference (RFI). According to previous studies, PSR J1727−2739 exhibits both nulling and subpulse drifting. Consistent with previously published results, we estimate the nulling fraction to be 66%±1.4%. In addition to the previously known subpulse drifting in the leading component, we also explore the drifting properties for the trailing component. There are two distinct drift modes whose vertical drift band separations (P3 ) are consistent with earlier studies. We find that both profile components share the same drift periodicity P3 in a certain drift mode, but the measured horizontal separations (P2 ) are quite different for them. That is, PSR J1727−2739 is a pulsar showing both changes of drift periodicity P3 between different drift modes and drift rate variations between components in a given drift mode. Pulsars exhibiting nulling along with drift mode changing, such as PSR J1727−2739, give an unique opportunity to investigate the physical mechanism of these phenomena. Chapter 4 presents a study of simultaneous single-pulse observations of PSR J0953+0755 at 732 and 3100 MHz made using the Parkes 64-m radio telescope at two epochs. We have also analysed another one non-simultaneous 1369 MHz observation to compare polarization properties of this pulsar at different frequencies. The previously reported low-level bridge emission between the interpulse and the main pulse is notably present at 732 MHz. However, the bridge emission becomes very weak or undetectable at higher frequencies. The cross-correlation analysis of simultaneous observations indicates that the total intensity of single pulses is highly correlated, which implies a same emissionmechanism responsible for the two frequencies. We confirm that the abrupt polarization angle (PA) jumps are non-orthogonal in this pulsar which probably results from the overlapping emission from two non-orthogonal polarization modes and the separation between different polarization modes is frequency-dependent. At all three frequencies, the dominant modes are clearly associated with negative values of circular polarization, but the association seems unclear for weak modes. |
| Pages | 106 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.xao.ac.cn/handle/45760611-7/5168 |
| Collection | 研究生学位论文 |
| Affiliation | 中国科学院新疆天文台 |
| First Author Affilication | Xinjiang Astronomical Observatory, Chinese Academy of Sciences |
| Recommended Citation GB/T 7714 | 茹克娅·热介甫. 脉冲星单脉冲辐射特性的观测研究[D]. 北京. 中国科学院大学,2022. |
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