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题名	一个射电噪类星体样本的XMM-Newton能谱的研究
作者	窦立明
学位类别	硕士
答辩日期	2007-06-29
授予单位	中国科学院研究生院（云南天文台）
授予地点	北京
导师	袁为民
关键词	射电噪类星体 X-ray辐射 核主导参数 统一模型
其他题名	XMM-Newton spectral study of a Radio-loud QSO sample
学位专业	天体物理
中文摘要	本论文主要研究射电噪类星体的X-ray辐射和它对类星体取向的依赖性。我们 采用了一个核主导参数分布跨度很大的射电噪类星体样本，其中包括核主导射电源5个（R $>$ 1.0），瓣主导射电源4个(R $<$ 0.5)，还有3个介于两者之间。我们分析了样本来自X-ray卫 星（主要来自XMM-Newton，还有一部分来自Chandra）的光谱数据。我们发现我们样本中 的所有源都至少需要一个主导硬X-ray波段的平的幂律分量。对核主导源（5/12），光子指数平均值$\Gamma$ $\sim$ 1.5；对于瓣主导 射电源（4/12），都可以用双幂律模型来拟合，较平的幂律成分的光子指数平均值$\Gamma$ $\sim$ 1.6，；对于介于两者之间的射电源（3/12），较平的幂律成分的光子指数 平均值$\Gamma$ $\sim$ 1.5。 我们检验了样本的X-ray辐射的可能来源：来自喷流的X-ray辐射、来自黑洞吸积盘-冕的X-ray辐射和来 自大尺度射电喷流外部或延展区的X-ray辐射。我们依照以前基于射电噪类星体的统一模型给出的来自喷流的X-ray光度 同5 GHz射电核区的光度依赖关系估算了来自喷流的X-ray辐射的光度；通过光学[O III]发射线光度或光学2500{\AA}的光度估计来自吸积盘-冕的X-ray辐射的光度。通过对比我们估计的X-ray光度和观测 到的X-ray光度，我们发现以下结果。对于样本中的核主导射电噪源，可以很好用来自相对论性喷流的辐射解释，其 辐射机制是逆康普顿散射，有很强的相对论集束放大效应。对于样本中的瓣主导射电噪源，虽然考虑我们所用的 两个相关关系的误差后可以解释个别源观测到的X-ray光度，但估计的来自喷流或吸积盘-冕的X-ray光度相 对于观测到的光度都系统性的显著偏小。部分样本源的Chandra的高分辨率成像显示尺度在几个kpc的核区的X-ray辐射 远大于来自大尺度的喷流或瓣区的X-ray辐射。同时，在个别源的较平幂律分量中还发现了其流量和光谱 存在年量级时标的大幅变化。基于以上事实，我们推测在瓣主导射电源发现的多余的较平幂律分量的X-ray辐射还是 主要来喷流，也就是说对于瓣主导射电源来自喷流的X-ray辐射比以前简单统一模型预期的要大。 基于这种情况，射电噪类星体的简单统一模型对于瓣主导射电源需要修正。这其中的物理原因还不清楚。 我们讨论了几种可能的解释：在瓣主导射电噪喷流的X-ray辐射主要有外逆康普顿散射主导， 或者X-ray喷流的张角与射电喷流的张角不同，或者喷流是弯曲的。我们还检验了射电喷流的内禀功率同黑洞质量、爱丁 顿比和吸积率之间的关系。 除了以上主要的论文工作外，我还参与了3项其他研究的合作工作，主要 承担其中的X-ray数据处理和分析部分，包括对一个窄线Seyfert星系样本的研究，矮星系SDSS J160531.84+174826.1中的活动星系核和中等质量黑洞的新发现和类星体 SDSS J144842.45+042403.1 中的奇特宽吸收线。
英文摘要	This thesis is mainly on the X-ray radiation from radio loud quasars and its dependence on quasar orientation. We compiled a sample of radio-loud quasars which samples over a large range of the radio core-dominance parameter R, including 5 core-dominated quasars (R $>$ 1.0), 4 lobe-dominated quasars (R $<$ 0.5), and 3 quasars with intermediate radio core-dominance. We analyzed their X-ray spectroscopic data from observations taken with the X-ray satellites, mostly with XMM-Newton and some with Chandra. We found that a flat power law component, which dominates at least the hard X-ray band, is needed to fit the X-ray spectra of all the objects in our sample. For core-dominated sources, the average photon index of the flat X-ray component is $\sim$1.5. For lobe-dominated sources, the X-ray spectra are best fitted with two power law components, with the average photon index of the flat component being $\sim$ 1.6. The average photon index of the flat component for intermediate core-dominance objects is $\sim$ 1.5. We examined the possible origins of the observed X-ray radiation, namely, emission from core-jets, black hole accretion disk-corona, as well as extended radio jets/lobes. We predicted X-ray emission from jets assuming the dependence of jet X-rays on radio 5 GHz core luminosity, as established in previous studies in the framework of the unified model of radio loud quasars. X-ray emission contributed from disk-corona was estimated from either the optical [O III] emission line luminosity or the optical luminosity at 2500{\AA}. By comparing the estimated and the observed X-ray luminosities, we found the following results. For the core-dominated sources in our sample, the observed X-ray luminosities can be satisfactorily explained by X-rays from the relativistic jets, which is produced via likely inverse-Compton radiation and is relativistically beamed. For the lobe-dominated sources, the superposition of the estimated X-rays from both, jets and disk-corona is systematically and significantly smaller than the observed X-ray luminosity, although scatters inherent in the estimation may explain the discrepancy for some individual objects. High spatial resolution X-ray imaging observations with Chandra of some of the sample objects show that the bulk of the X-ray emission comes from the compact, unresolved core of a few kilo-parsec in scale, rather than from diffuse emission of radio lobes or large scale jets. Furthermore, flux and spectral variability in the flat component has also been found in a few objects having more than one epoch observation on timescales of years. Based on these facts, we postulate that the excess flat X-ray emission found in the lobe-dominated sources is actually from the jets, i.e. the X-ray emission from jets in these objects is actually stronger than that predicted by the current unification model. If this is the case, the simple unification model for radio-loud quasars needs to be modified. The underlying physical reason for this finding is not clear. We discussed some possible mechanisms in terms of the dominance of external inverse-Compton scattering in lobe dominated sources, or X-ray and radio jets having different opening angles, or bending jets. We also examined the relationship between the intrinsic power of radio jets with black hole mass, Eddington ratio, and mass accretion rate. Besides the main thesis work above, I was also involved in 3 other research projects, in which I mainly worked on X-ray data analysis. These include studies of a sample of narrow line Seyfert AGN, the newly discovered dwarf AGN with an intermediate mass black hole SDSS J160531.84+174826.1, and the peculiar broad absorption line quasar SDSS J144842.45+042403.1.
语种	中文
学科主题	天文学
页码	85
内容类型	学位论文
源URL	[http://ir.ynao.ac.cn/handle/114a53/5077]
专题	云南天文台_高能天体物理研究组
推荐引用方式 GB/T 7714	窦立明. 一个射电噪类星体样本的XMM-Newton能谱的研究[D]. 北京. 中国科学院研究生院（云南天文台）. 2007.

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