本文關(guān)鍵詞：射電噪活動(dòng)星系核的光度函數(shù)與演化研究　出處：《中國(guó)科學(xué)院研究生院（云南天文臺(tái)）》2013年博士論文　論文類型：學(xué)位論文

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【摘要】：射電噪活動(dòng)星系核（radio-loud AGN）是宇宙中的強(qiáng)射電源，常將這類天體分為平譜源和陡譜源，按照AGN的統(tǒng)一模型，它們的差異很大程度上源于傾角的不同，兩類源都可以用“致密核+噴流+延展射電瓣”的圖像來描述。在傳統(tǒng)的方法中，人們通過獨(dú)立地研究陡譜源和平譜源的射電光度函數(shù)來獲得它們的演化信息。然而，由于AGN射電輻射和活動(dòng)本身的特點(diǎn)，例如延展性、方向性、間歇性等，使得傳統(tǒng)方法獲得的信息比較有限。隨著射電觀測(cè)精度的日益提高，已觀測(cè)到大量的射電核，射電核的存在是AGN射電活動(dòng)性很好的指示。本論文利用現(xiàn)有的觀測(cè)資料，研究了射電核的光度函數(shù)。由于射電核處在AGN的中心位置，對(duì)其光度函數(shù)的研究，可以更直接地探究AGN中心區(qū)域物質(zhì)吸積與噴流的關(guān)系。 首先我們通過文獻(xiàn)查閱和數(shù)據(jù)庫(kù)檢索，建立了一個(gè)包含1063個(gè)源的陡譜射電噪活動(dòng)星系核樣本，基于此樣本，用1/Va方法計(jì)算了這類射電源在408MHz處的射電光度函數(shù)，我們的結(jié)果支持一個(gè)光度依賴的密度演化模式。大多數(shù)源的射電核有5GHz處的流量密度數(shù)據(jù)，利用這些數(shù)據(jù)我們又計(jì)算了射電核在5GHz處的光度函數(shù)。結(jié)果表明射電核的共動(dòng)數(shù)密度是隨紅移增加而逐漸減小的，即呈現(xiàn)出一種負(fù)宇宙演化模式。對(duì)此結(jié)果，一個(gè)很好的解釋是：在AGN早期，吸積率可能較高，反而不利于jet的射電輻射，甚至于jet的產(chǎn)生，在AGN中可能也有類似于X射線雙星的“軟”態(tài)和“硬”態(tài)的演化。我們的結(jié)果與前人從不同角度所得到的結(jié)論也是一致的。我們還注意到射電核的光度函數(shù)與源的總射電光度函數(shù)形式完全不同，由于我們樣本的源都是瓣主導(dǎo)的陡譜源，這說明核和瓣并不是協(xié)同演化的。 此外，我們回顧了經(jīng)典的、用于估計(jì)光度函數(shù)的1/Va方法，以及PC方法，并通過圖像分析的方法對(duì)二者做了比較。通過理論分析和實(shí)例證明，我們指出了兩種方法對(duì)于那些被極限流量曲線L=Llim(z)穿過的小間隔（bin）總是會(huì)給出不同估計(jì)的原因之所在�；谝粋�(gè)由蒙特卡洛方法模擬出的虛擬樣本，我們比較了兩種方法給出的估計(jì)與輸入模型值的差異。結(jié)果發(fā)現(xiàn)，兩種方法對(duì)高光度的那些bin給出的估計(jì)完全相同而且比較理想，但是對(duì)低光度的那些bin，兩者給出的估計(jì)都顯著地低于輸入模型值。我們認(rèn)為，只要光度函數(shù)沿著紅移有演化，那么傳統(tǒng)的、需要?jiǎng)澐珠g隔的非參數(shù)方法就不可能在整個(gè)光度區(qū)間都給出理想的估計(jì)。前人注意到對(duì)于光度函數(shù)的暗端，1/Va給出的結(jié)果總是太小，從而認(rèn)為PC方法要優(yōu)于1/Va方法。實(shí)際上這只是由于隨意選取bin的緣故。我們提出了一種簡(jiǎn)單有效的選擇bin的方法，運(yùn)用此方法，可以對(duì)兩種方法的結(jié)果都有不同程度的改進(jìn)。經(jīng)過改進(jìn)后，，很難說PC方法的結(jié)果要比1/Va方法的更優(yōu)越。
[Abstract]:Radio-loud AGNN (Radio-loud AGNN) is a powerful radio source in the universe. It is often classified as a flat spectral source and a steep spectral source, according to the unified model of AGN. Their differences are largely due to different dip angles, and both types of sources can be described by images of "dense nuclear jet extended radio lobes." in traditional methods. The evolution information is obtained by studying the radio luminosity functions of steep spectral sources and spectral sources independently. However, due to the characteristics of AGN radio radiation and activity itself, such as ductility, directionality, intermittency, etc. With the increasing accuracy of radio observation, a large number of radio cores have been observed. The existence of radio nuclei is a good indication of the radio activity of AGN. In this paper, the luminosity function of radio nuclei is studied by using the available observation data. Because the radio nuclei are located at the center of AGN. The study of its luminosity function can more directly explore the relationship between mass accretion and jet flow in the central region of AGN. Firstly, we establish a steep-spectrum radio noised active galactic nucleus (AGNs) sample containing 1063 sources based on literature review and database retrieval. The radio luminosity function of this kind of radio source at 408 MHz is calculated by using the 1 / V a method. Our results support a photometric dependent density evolution model. Most source radio cores have flow density data at 5GHz. Using these data, we calculate the luminosity function of the radio nucleus at 5GHz. The results show that the density of the coaction number of the radio nucleus decreases with the increase of the red shift. A good explanation for this result is that the accretion rate may be higher in the early stage of AGN, which is not conducive to the radio radiation of jet, even to the production of jet. There may also be "soft" and "hard" states similar to X-ray binaries in AGN. Our results are consistent with the previous conclusions from different angles. We also note that the photometric function of the radio nucleus is completely different from the total radio photometric function of the source. Since the source of our sample is a petal-dominated steep spectrum source, this indicates that the kernel and lobe are not coevolved. In addition, we review the classical 1 / Va method used to estimate the photometric function and the PC method, and compare them with the image analysis method. We point out two methods for small interval bindings that are crossed by the limit flow curve Ln Llimz). The reasons for different estimates are always given based on a virtual sample simulated by the Monte Carlo method. We compare the differences between the estimates given by the two methods and the values of the input model. The results show that the estimates given by the two methods for those bin with high luminosity are identical and ideal. But for those bines with low luminosity, both estimates are significantly lower than the input model values. We think that as long as the photometric function evolves along the redshift, then the tradition is. It is impossible to give an ideal estimate in the whole luminosity region by the nonparametric method which needs to divide the interval. It has been noted that the results given for the dark end of the photometric function 1 / V a are always too small. It is concluded that the PC method is better than the 1 / V a method. In fact, this is only due to the random selection of bin. We propose a simple and effective method to select bin, and use this method. After improvement, it is difficult to say that the result of PC method is better than that of 1 / V a method.
【學(xué)位授予單位】：中國(guó)科學(xué)院研究生院（云南天文臺(tái)）
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2013
【分類號(hào)】：P157.6;P161

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 朱杏芬,褚耀泉;類星體的光度函數(shù)[J];天文學(xué)進(jìn)展;1996年01期

本文編號(hào)：1428644