發(fā)布時(shí)間：2018-11-09 07:33

【摘要】：活動(dòng)星系核(Active Galactic Nucleus)的中心以一個(gè)超大質(zhì)量的黑洞為引擎,周圍是環(huán)繞著黑洞旋轉(zhuǎn)的吸積盤。黑洞吸積周圍的物質(zhì),將引力能轉(zhuǎn)化為輻射能,由于吸積的物質(zhì)具有角動(dòng)量,下落的過程中會環(huán)繞黑洞形成吸積盤,吸積盤上發(fā)出光學(xué)、紫外、X射線等波段的輻射。在吸積盤兩側(cè)存在著相對論性噴流,噴流上幾乎存在著各個(gè)波段的輻射。活動(dòng)星系核有一個(gè)子類叫Blazar天體,由于觀測者的視線方向與噴流的方向只有很小的夾角,所以觀測上有一些極端的性質(zhì),如大幅度快速光變、高且變化的偏振、視超光速運(yùn)動(dòng)等。Blazars在觀測上顯示出不同變化時(shí)標(biāo),不同變化幅度混合的復(fù)雜光變,光變與天體內(nèi)在的結(jié)構(gòu)和機(jī)制相聯(lián)系。對于如此復(fù)雜的變化,是需要引入統(tǒng)計(jì)方法對其進(jìn)行定性和定量的分析。對光變的類型進(jìn)行統(tǒng)計(jì)是一個(gè)很有意義的工作。前人在Blazar天體光變研究中,多集中在光變中的準(zhǔn)周期信號,有一系列的周期被發(fā)現(xiàn)。也有很多研究者從另一個(gè)角度出發(fā),發(fā)現(xiàn)Blazars天體的光變曲線在頻域上服從冪律,類似于紅噪聲,但沒有進(jìn)一步的深入研究。在此工作中,采用了最簡單的紅噪聲模型—布朗噪聲或高斯過程,來檢驗(yàn)Blazars天體的光變曲線是否與之相類似。在具體做法上,第一步采用K-S檢驗(yàn)來比較130個(gè)源的每日流量變化的分布與高斯分布是否一致,結(jié)果表明大多數(shù)源的每日流量變化分布與高斯分布相同的置信度小于1%,說明光變可能與Blazar天體的內(nèi)部物理機(jī)制有關(guān);第二步將任意兩個(gè)源的每日流量變化分布用K-S檢驗(yàn)進(jìn)行比較,發(fā)現(xiàn)有些源之間的分布很相似,說明那些相類似的源之間可能有相同的物理機(jī)制;由于的每日流量變化分布與高斯分布不相似,所以第三步檢驗(yàn)了分布兩翼的偏差,發(fā)現(xiàn)負(fù)的每日流量變化的分布比正的每日流量變化的分布要更平坦,這說明負(fù)的部分彌散比正的部分大,即負(fù)的部分,流量變化的尺度時(shí)大時(shí)小,而正的部分,流量變化的尺度基本差不多;第四步計(jì)算了分布的偏度和峰度,發(fā)現(xiàn)峰度隨著偏度的增加而增加。
[Abstract]:The center of the AGNs (Active Galactic Nucleus) is a supermassive black hole, surrounded by accretion disks orbiting the black hole. The matter around the accretion of the black hole is converted into radiation energy. Because the accretion material has angular momentum, it will form accretion disk around the black hole in the process of falling. The accretion disk emits optical, ultraviolet and X-ray radiation. There are relativistic jets on both sides of the accretion disk. The active galactic nucleus has a subclass called the Blazar object. Because the observer has only a very small angle of view to the direction of the jet, there are some extreme properties in the observations, such as large, fast light changes, high and varying polarization. The apparent superluminal motion and so on. The observation of Blazars shows that the complex light variation with different time scales and different variation amplitude is related to the inner structure and mechanism of the celestial body. For such complex changes, it is necessary to introduce statistical methods to analyze them qualitatively and quantitatively. It is a meaningful job to count the types of light change. In the study of Blazar celestial light variation, most of the quasi-periodic signals are concentrated in the light variation, and a series of periods have been discovered. From another point of view, many researchers have found that the optical variation curve of Blazars objects obeys the power law in frequency domain, similar to Yu Hong noise, but there is no further study. In this work, the simplest red noise model-Brownian noise or Gao Si process is used to test whether the optical curve of Blazars objects is similar to it. In the specific practice, the first step is to use K-S test to compare whether the distribution of daily flow changes of 130 sources is consistent with that of Gao Si. The results show that the daily flow variation distribution of most sources is the same as that of Gao Si, and the confidence level is less than 1. It is suggested that the light variation may be related to the internal physical mechanism of Blazar objects. In the second step, the distribution of daily flux of any two sources is compared with K-S test, and it is found that the distribution of some sources is very similar, which indicates that there may be the same physical mechanism among those similar sources. Since the distribution of daily flow changes is not similar to that of Gao Si, the third step examines the deviation of the two wings of the distribution, and finds that the distribution of the negative daily flow changes is more flat than that of the positive daily flow changes. This shows that the negative part is larger than the positive part, that is, the negative part, the scale of flow change is large and small, and the positive part, the scale of flow change is almost the same; In the fourth step, the skewness and kurtosis of the distribution are calculated, and it is found that the kurtosis increases with the increase of skewness.
【學(xué)位授予單位】：廣州大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：P145.8;P157.6

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本文編號：2319761