【作者】 王洪涛；

【导师】 施勇；

【作者基本信息】 南京大学 ， 天文学， 2019， 博士

【摘要】 类星体自上世纪60年代被发现以来,就一直是天体物理领域的研究热点之一。而类星体最显著的特点之一就是具有很强的光变。因此,对类星体光变的研究就成为我们了解类星体内部物理机制的主要手段之一。本论文从光变的角度对类星体进行了系统性研究,主要的三个成果如下:1.基于从类星体斯隆巡天样本中随机选取的144个射电静类星体,我们对它们在光学波段的光变进行了分析。结构函数法的结果表明这些源总体是符合阻尼随机游走模型的,逐一进行分析的结果显示其中有10个源可能偏离阻尼随机游走模型,进一步用模拟的光变曲线进行验证表明其中有70%的概率偏离阻尼随机游走模型。2.基于斯隆DR7类星体样本,结合来自于WISE卫星的红外数据,我们对类星体中红外波段的光变进行了分析研究,结果分为下面四部分:(1).结构函数在1年处的光变并没有显示出随热光度、红移、黑洞质量以及爱丁顿比的变化。(2).在W1波段和W2波段结构函数的斜率要比前人的结果略陡,我们认为可能是由于WISE不同的采样率造成的。(3).我们进一步调研了中红外波段光变幅度与光学波段光变幅度的关系,结果并没有表现出明显的相关性。同时进一步调研了类型体中红外波段色指数和光学波段色指数的关系,也没有发现明显的相关性。我们认为可能是由于来自更大更延展辐射区域的中红外辐射被平滑掉了,从而使得它们之间的相关性表现得不明显。(4).我们基于射电噪子样本进一步分析了中红外波段的光变幅度与射电1.4 GHz功率之间的关系,但从结果来看并没有发现它们之间可能存在的相关性,这表明射电噪类星体的中红外辐射中来自相对论喷流部分的贡献可能是比较弱的。3.我们结合Pan-STARRS1的测光数据对窄线Seyfert 1(NLS1)星系光学波段的光变性质进行了分析,结果如下:(1).我们分析了NLS1星系的光变幅度随相应波段光度的变化,结果显示随着源的变亮NLS1星系在光学波段的光变幅度呈现出明显变弱的趋势,与前人的分析结果一致。(2).我们进一步分析了NLS1星系的光变幅度随MBH、L5100A、爱丁顿比等参数的变化,结果表明NLS1星系的光变随这些参数的变化没有呈现出明显的相关性。(3).最后,我们分析了NLS1星系的光变幅度随射电噪度的变化,结果显示随着射电噪度的增加NLS1星系的光变呈现出比较明显增大的趋势。同时我们进一步分析了NLS1星系的光变与射电1.4 GHz功率的关系,并没有发现光变与1.4 GHz功率的相关性。我们认为可能是由于NLS1星系光学波段的光变较弱,从而从统计角度比较难发现喷流成分对射电光变的贡献。我们下一步计划对光变较强的几个NLS1的光变进行更加细致的研究,来进一步验证射电喷流部分对光学波段光变可能存在的贡献。最后,我们对类星体光变领域的未来发展趋势进行了展望。随着诸如LSST、eROSITA等巡天项目的不断投入使用,类星体领域期待会有更多激动人心的发现。更多还原

【Abstract】 Since the 1960s,the quasar was fist discovered which was always one of the hot topic field in astrophysics.Extreme variability is one characteristics of quasars.Therefore,the study on variability of quasars is one means for us to understand the physical mech-anism in quasars.The thesis study the variability of quasar carefully.The three works in variability aspects are listed as follows.First,we mainly study the variability of 144 radio quiet quasars from random se-lection in SDSS.The ensemble result indicates it is consistent with the damped random walk(DRW)model.The individual result suggest ten objects are deviated from the damped random walk model.We further examine the probability deviating from the damped random walk model by simulating light curve,which present 70%probability deviated from the DRW model.Second,we select the data release 7 quasar sample and analyze the mid-infrared variability of quasars.The analysis are presented as follows,(1).There are no obvious variation between the structure function in one year and bolometric luminosity,black hole mass as well as Eddington ratio.(2).The slopes in W1 band and W2 band are steeper than that in previous studies,which may be caused by different sampling.(3).We further investigate the relationship of variability amplitude between optical band and mid-infrared band.No obvious trend is found.We also investigate the color re-lationship between W1-W2 and g-r,which shows no obvious correlation.We think it may be smoothed out by the extended emission region in infrared band.(4).We select a radio-loud subsample to investigate the relationship between variability amplitude and radio power at 1.4 GHz,thus the results suggest they are no obvious correlation.The results indicate the mid-infrared emission originated from relativistic jet is weak.Third,we investigate the optical variability of a large narrow-line Seyfert 1 sample,and the optical data sets are from Pan-STARRS1.The results are listed as follows,(1).We analyze the variability amplitude with the luminosity in g,r,i,z and y bands.The results suggest the amplitude become weaker with brighter,which is consistent with previous results.(2).We analyze the relation between variability amplitude and MBH.L5100A and other parameters,but no previous correlations are found in our results.(3).At last,we analyze the relation between variability amplitude and radio power at 1.4 GHz,but also no obvious correlations are found.The variability in narro-line Seyfert 1 galaxies is weak in optical band,then it is difficult to find the contribution of variation from relativistic jet by statistical method.In order to probe the contribution from relativistic jet,we will mainly focus on a few narrow-line Seyfert 1 galaxies with strong variability in the future.At last,the development in the field of quasar in the future is included in section five.With the LSST,eROSITA,etc will be put into use,we anticipate much more exciting discovery in the field of quasar.更多还原