基于RXTE实测数据的X射线脉冲星信号特征研究

发布时间：2018-05-31 12:28

本文选题：X射线脉冲星 + 宇宙X射线背景噪声　；参考：《西安电子科技大学》2014年硕士论文

【摘要】：近年来,X射线脉冲星导航作为一种新型的自主导航方式已成为一个研究热点。但是X射线光子信号被淹没在强宇宙背景噪声中,单纯依靠周期叠加难以在短时间内获得高质量的脉冲轮廓,从而影响脉冲到达时间的估计精度。周期特性的研究不仅能够获得准确的周期来提高脉冲到达时间的估计精度,而且有利于脉冲星时的研究。因此,有必要研究X射线脉冲星的信号特征。本文首先对宇宙背景噪声进行了深入研究,通过对美国RXTE卫星的大量实测数据的处理,获取了宇宙X射线背景的流量、能级、分布、历元折叠等特性,表明：2-10keV能级范围对应的光子均值流量最强约为50 ph/s/m2；宇宙X射线背景光子的到达时间服从泊松分布且,泊松分布的强度参数为的平均流量；在历元折叠过程中,宇宙X射线背景光子的影响在每个bin块内都是0均值等方差且不相关的高斯白噪声。其次,利用实测数据对常用的周期搜索算法的搜索精度进行研究,提出了将FFT搜索算法与卡方搜索算法相结合的周期搜索方法。该方法首先利用FFT搜索算法进行粗搜索,为卡方搜索算法提供初始搜索范围,减少了搜索时间,然后利用多项式拟合处理实测数据引起的毛刺现象,提高了卡方搜索的精度。因此,该方法可以在短时间内获得高的搜索精度。最后,利用RXTE多年的观测数据,对Crab脉冲星的周期漂移特性、周期稳定性进行了研究。研究结果表明Crab脉冲星的周期漂移率为-3.731×10-10s/s,在时间间隔为30 s、60 s和1000 s时的稳定度分别为2.1931e-006、1.5874e-006与3.3324e-007。
[Abstract]:In recent years, X-ray pulsar navigation as a new type of autonomous navigation has become a research hotspot. But the X-ray photon signal is submerged in the strong cosmic background noise, so it is difficult to obtain high quality pulse profile in a short time by using period superposition alone, thus affecting the estimation accuracy of the pulse arrival time. The study of periodic characteristics can not only obtain accurate periods to improve the accuracy of pulse arrival time estimation, but also be beneficial to the study of pulsar time. Therefore, it is necessary to study the signal characteristics of X-ray pulsars. In this paper, the cosmic background noise is studied in depth. By processing a large number of measured data from the RXTE satellite of the United States, the characteristics of the cosmic X-ray background, such as flow rate, energy level, distribution, epoch folding and so on, are obtained. It shows that the mean photon flux corresponding to the energy level of: 2-10 Kev is the strongest about 50 phps / s / m ~ 2; the arrival time of photon in cosmic X-ray background is from Poisson distribution and the intensity parameter of Poisson distribution is the average flux; in the folding process of epoch, The effect of cosmic X-ray background photons on each bin block is an uncorrelated Gao Si white noise with equal variance of 0 mean. Secondly, the search accuracy of the commonly used periodic search algorithm is studied by using the measured data, and the periodic search method which combines the FFT search algorithm with the chi-square search algorithm is proposed. In this method, the initial search range is provided for chi-square search algorithm, and the searching time is reduced by using FFT search algorithm. Then, the burr phenomenon caused by measured data is treated by polynomial fitting, and the precision of chi-square search is improved. Therefore, the method can obtain high search accuracy in a short time. Finally, the periodic drift characteristics and the periodic stability of Crab pulsars are studied by using the observed data of RXTE for many years. The results show that the periodic drift rate of Crab pulsar is -3.731 脳 10 ~ (-10) s / s, and the stability is 2.1931 e-006 ~ 1.5874e-006 and 3.3324 ~ (e-007) when the time interval is 30 s ~ 60 s and 1000 s, respectively.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN966

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