BL Lac天体的光变研究

发布时间：2018-10-25 07:52

【摘要】：BL Lac天体是活动星系核中性质最为奇特的子类之一,它们普遍具有大幅且快速的多波段光变。光变是研究BL Lac天体物理特性的一种有力工具。通过研究BL Lac天体的光变,可以限制其辐射机制和辐射区域物理过程等。虽然BL Lac天体的光变观测已经有一百多年的观测历史,但是由于其光变的随机性和光学能谱变化的复杂性,其中很多物理性质还需要更多的观测数据进行限制。本文第一章简单介绍了活动星系核和blazar的基本特征、分类和统一模型等。第二章介绍了BL Lac天体的发现、基本特征和多波段能谱的分布。第三章介绍了BL Lac天体不同时标光变的观测结果和光变的产生机制。第四章简单介绍了BL Lac天体的测光观测和孔径测光流程。第五章介绍了我们利用云南天文台的多色测光数据,对一个典型的BL Lac天体OJ 287的光变分析。最后,对整个论文的内容进行了总结。OJ 287(0851+202,红移0.306)是一个典型的BL Lac天体,是目前唯一被确定具有长时标光变周期的BL Lac天体。从2006年到2012年,我们对其进行了长期的多色光学监测。利用这些数据,我们对OJ 287的光变时标、光变过程中谱形的变化和不同波段间光变的相关性进行了分析,此外结合SMARTS和Steward天文台的观测数据,对OJ 287的长时标色指数和周期进行了分析。通过对三个波段时延的分析,我们发现不论短时标还是长时标,三个波段之间并没有发现显著的时延。对于一天内的色指数,通过对V和I波段之间的分析,我们发现OJ 287显示强的变亮变蓝的趋势;对长时标而言,也显示了变亮变蓝趋势。说明OJ 287的色指数由变亮变蓝的趋势所主导,这个结果支持了喷流激波模型。通过对2006年到2017年V和R波段的周期性分析,我们发现一些可能的周期,分别是513、176、36、30、26、17和14天。这些周期的形成可能是由于喷流的进动,喷流的螺旋形磁场,或者吸积盘的轨道周期。
[Abstract]:BL Lac objects are one of the most peculiar subclasses of active galactic nuclei (AGNs). They generally have large and fast multiband light variations. Photovariability is a powerful tool for studying the physical properties of BL Lac astrophysics. The radiation mechanism and the physical processes of the radiation region can be restricted by studying the light variation of the BL Lac celestial body. Although BL Lac objects have been observed for more than one hundred years, due to their randomness and complexity of optical spectrum variation, many of the physical properties need to be limited by more observational data. In the first chapter, we briefly introduce the basic characteristics, classification and unified model of AGNs and blazar. In the second chapter, the discovery, basic characteristics and multiband energy spectrum distribution of BL Lac objects are introduced. In chapter 3, we introduce the observation results and the mechanism of light variation of BL Lac objects at different time scales. In chapter 4, the flow of photometry and aperture photometry of BL Lac objects is briefly introduced. In chapter 5, we use the polychromatic photometry data of Yunnan Observatory to analyze the optical variation of a typical BL Lac object OJ 287. Finally, the whole thesis is summarized. OJ 287 (0851 2022, Redshift 0.306) is a typical BL Lac object, which is the only BL Lac object that has been determined to have a long period of light variation. From 2006 to 2012, we carried out long-term multi-color optical monitoring. Using these data, we analyze the optical time scale of OJ 287, the variation of spectral shape in the process of optical transformation and the correlation between different wavelengths. In addition, we combine the observational data of SMARTS and Steward observatories. The long time scale color index and period of OJ 287 are analyzed. Through the analysis of the time delay in the three bands, we find that there is no significant delay between the three bands, regardless of the short time scale or the long time scale. Based on the analysis between V and I bands, we find that OJ 287 shows a strong trend of brightening and turning blue, as well as a trend of brightening and turning blue for a long time scale. It shows that the color exponent of OJ 287 is dominated by the trend of changing brightness to blue, which supports the jet shock model. Based on the periodic analysis of V and R bands from 2006 to 2017, we have found that some possible periods are 513 ~ 1766 ~ 36 ~ 30 ~ 2617 and 14 ~ (th) days, respectively. These periods may be due to the precession of the jet, the spiral magnetic field of the jet, or the orbital period of the accretion disk.
【学位授予单位】：中国科学院大学(中国科学院云南天文台)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P157.7

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