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研究生： 陸勇志
Loke, Young Tzee
論文名稱： Color Variabilities of QSOs at z = 0.3 - 1.2
指導教授： 黃崇源
Chorng-Yuan Hwang
口試委員:
學位類別： 博士
Doctor
系所名稱： 理學院 - 天文研究所
Graduate Institute of Astronomy
論文出版年： 2019
畢業學年度： 107
語文別： 英文
論文頁數： 86
中文關鍵詞： 類星體 、活躍星系核 、星系
外文關鍵詞： QSO, AGN, Galaxy
相關次數： 點閱：25  下載：0 
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    • 我們研究了類星體的顏色變化的特性。我們交叉比對史隆數位化巡 (SDSS) 所釋出的第七版資料 (DR 7) 和第十二版資料 (DR 12) 的類星體目錄，選出 608 個在兩個版本都有觀測資料且紅移在 0.3 到 1.2 之間的類星體。我們選用在靜止坐標系下 3000 埃與 4000 埃的光通量密度比值來定義顏色值。我們透過比較兩個版本類星體的顏色值來定義顏色變化。我們發現在靜止坐標系下，類星體的顏色變化分佈類似常態分佈，但部分類星體在數年的時間尺度下有著明顯的顏色變化。另外，我們還發現了八個類星體的光譜變化可以被塵埃紅化現象來解釋。我們的結果也顯示了類星體的顏色變化可能存在多個物理機制。

    We investigate the color variabilities of QSOs at z = 0.3 – 1.2. We selected the sample of 608 QSOs, which have multi-epoch spectra in both the Sloan Digital Sky Survey (SDSS) Data Released 7 (DR7) and Data Released 12 (DR12). We defined the spectral color ofthe QSOs by the ratio of flux densities of 3000 Å to 4000 Å in the rest frame. In each sample, the color variability is defined by the differences of color in DR7 and DR12.We find that the color variabilities show a Gaussian distribution with some QSOs displaying significant color changes within the timescale of a few years. We find that the spectral variabilities of eight color-change QSOs could be explained by dust reddening. Our results also show that the color variabilities of QSOs might originate from more than one physics mechanisms.

    摘要 vii Abstract ix Contents xi List of Figures xiii 1 Introduction 1 1.1 Active Galactic Nucleus....................................................... 1 1.2 Unification model ............................................................. 2 1.3 Subclass of QSOs.............................................................. 3 1.4 Red QSOs ..................................................................... 4 1.5 Variabilities of QSOs.......................................................... 4 2 Sample Selection 7 2.1 Spectroscopic Data............................................................ 7 2.2 Sample Selection and Defi nition of the Color ................................ 8 2.3 Defi nition of Color-change QSOs ............................................. 9 3 Results 11 3.1 Redshift Distribution of Color-change QSOs ................................. 11 3.2 Time Distribution of Color-change QSOs .................................... 13 3.3 Color of QSOs................................................................. 14 4 Discussions 25 4.1 Host Galaxy Contamination .................................................. 25 4.2 Dust reddening of the QSOs continuum...................................... 26 4.3 The intrinsic variabilities of QSOs............................................ 33 5 Conclusion 35 Bibliography 37 A Information of the selected QSOs 39 B Spectra of the color-change QSOs 61 C Example spectra of the controlled QSOs 69

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