本文選題：X射線脈沖星 + 宇宙X射線背景噪聲　； 參考：《西安電子科技大學(xué)》2014年碩士論文

【摘要】：近年來(lái),X射線脈沖星導(dǎo)航作為一種新型的自主導(dǎo)航方式已成為一個(gè)研究熱點(diǎn)。但是X射線光子信號(hào)被淹沒(méi)在強(qiáng)宇宙背景噪聲中,單純依靠周期疊加難以在短時(shí)間內(nèi)獲得高質(zhì)量的脈沖輪廓,從而影響脈沖到達(dá)時(shí)間的估計(jì)精度。周期特性的研究不僅能夠獲得準(zhǔn)確的周期來(lái)提高脈沖到達(dá)時(shí)間的估計(jì)精度,而且有利于脈沖星時(shí)的研究。因此,有必要研究X射線脈沖星的信號(hào)特征。本文首先對(duì)宇宙背景噪聲進(jìn)行了深入研究,通過(guò)對(duì)美國(guó)RXTE衛(wèi)星的大量實(shí)測(cè)數(shù)據(jù)的處理,獲取了宇宙X射線背景的流量、能級(jí)、分布、歷元折疊等特性,表明：2-10keV能級(jí)范圍對(duì)應(yīng)的光子均值流量最強(qiáng)約為50 ph/s/m2；宇宙X射線背景光子的到達(dá)時(shí)間服從泊松分布且,泊松分布的強(qiáng)度參數(shù)為的平均流量；在歷元折疊過(guò)程中,宇宙X射線背景光子的影響在每個(gè)bin塊內(nèi)都是0均值等方差且不相關(guān)的高斯白噪聲。其次,利用實(shí)測(cè)數(shù)據(jù)對(duì)常用的周期搜索算法的搜索精度進(jìn)行研究,提出了將FFT搜索算法與卡方搜索算法相結(jié)合的周期搜索方法。該方法首先利用FFT搜索算法進(jìn)行粗搜索,為卡方搜索算法提供初始搜索范圍,減少了搜索時(shí)間,然后利用多項(xiàng)式擬合處理實(shí)測(cè)數(shù)據(jù)引起的毛刺現(xiàn)象,提高了卡方搜索的精度。因此,該方法可以在短時(shí)間內(nèi)獲得高的搜索精度。最后,利用RXTE多年的觀測(cè)數(shù)據(jù),對(duì)Crab脈沖星的周期漂移特性、周期穩(wěn)定性進(jìn)行了研究。研究結(jié)果表明Crab脈沖星的周期漂移率為-3.731×10-10s/s,在時(shí)間間隔為30 s、60 s和1000 s時(shí)的穩(wěn)定度分別為2.1931e-006、1.5874e-006與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.
【學(xué)位授予單位】：西安電子科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TN966

【參考文獻(xiàn)】

相關(guān)碩士學(xué)位論文 前1條

1 劉琳;脈沖星的積分輪廓的高斯擬合及譜指數(shù)的研究[D];西南大學(xué);2011年

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本文編號(hào)：1959681