The Relation between the Inclinations of Broad Line Regions and the Accretion Disk     

Wei-Hao BianNational Astronomical Observatories  Chinese Academy of Sciences  Beijing Department of Physics  Nanjing Normal University  Nanjing   《中国天文和天体物理学报》2005,5(1):21-26

According to the standard model, an active galactic nucleus (AGN) consists of an inner accretion disk with a jet around a central massive black hole, and a number of outer broad line regions (BLRs) and narrow line regions (NLRs). The geometrical relationship between the BLRs and the accretion disk is not well understood. Assuming the motion of the BLRs is virialized and its configuration is disk-like, we derived its inclination to the line of sight for a sample of AGNs from their bulge stellar velocity dispersion, their size of the BLRs and their Hβ linewidth. Compared with the inclination of the accretion disk obtained from the X-ray Fe Kα emission lines, we found that there is no positive correlation between the two. Our results showed that BLRs are not coplanar with the accretion disk and that we should be cautious of using the BLRs inclination as the disk inclination. The non-coplanar geometry of the outer BLRs and the inner accretion disk provides clues to the origin of BLRs and the properties of the accretion disk. Our preferable interpretation is that BLRs arise out of the outer part of a warped accretion disk.  相似文献   

天文学进展第29卷2011年总目录     

《天文学进展》2011,(4):477-478

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An Analytic Model of Galactic Winds and Mass Outflows     

Cheng-Gang Shu  Hou-Jun Mo  Shu-De Mao Joint Center for Astrophysics  Shanghai Normal University  Shanghai  cgshu@center. shao. ac. cn Shanghai Astronomical Observatory  Chinese Academy of Sciences  Shanghai Max-Planck-Institut fur Astrophysik  Karl-Schwarzschild-Strasse  Postfach D- Garching  Germany Astronomy Department  University of Massachusetts  Amherst  MA  USA Jodrell Bank Observatory  Univ. of Manchester  Macclesfield  Cheshire SK DL  UK 《中国天文和天体物理学报》2005,5(4):327-346

Galactic winds and mass outflows are observed both in nearby starburst galaxies and in high-redshift star-forming galaxies. We develop a simple analytic model to understand the observed superwind phenomenon with a discussion of the model uncertainties. Our model is built upon the model of McKee & Ostriker for the interstellar medium. It allows one to predict how properties of a superwind, such as wind velocity and mass outflow rate, are related to properties of its starforming host galaxy, such as size, gas density and star formation rate. The model predicts a threshold of star formation rate density for the generation of observable galactic winds. Galaxies with more concentrated star formation activities produce superwinds with higher velocities. The predicted mass outflow rates are comparable to (or slightly larger than) the corresponding star formation rates. We apply our model to both local starburst galaxies and high-redshift Lyman break galaxies, and find its predictions to be in good agreement with current observations. Our model is simple and so can be easily incorporated into numerical simulations and semi-analytical models of galaxy formation.  相似文献   

伴有OH 1720 MHz脉泽发射的混合形态超新星遗迹的X射线特征研究     

俞志尧 《天文学报》2005,46(2):145-150

在银河系中，超新星遗迹的射电巡视揭示了19个伴有OH1720MHz脉泽发射的超新星遗迹．在从超新星遗迹膨胀到分子云的激波波面的后面产生了这一类不寻常的脉泽源．这个模型的重要点是从超新星遗迹来的X射线促使产生OH分子．研究伴有OH1720MHz脉泽发射的混合形态超新星遗迹的X射线特征是很重要的．研究了这19个伴有OH1720MHz脉泽发射的混合形态超新星遗迹的X射线特征．得到了这些源的X射线物理参数之间的一些相关关系和反相关关系．X射线电离率ζ与θ、D、r、r^2等物理量均不相关，而与Lx之间存在着正相关关系．另外超新星遗迹的X射线光度与相伴的OH1720MHz脉泽的最弱的束流量密度之间存在着紧密的正相关关系．这些都说明从超新星遗迹来的X射线发射足够在激波波阵面后面分解水分子并产生OH1720MHz脉泽．  相似文献   

The Optical Variability of 3C 273     

《中国天文和天体物理学报》2001,1(3):245-249

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银河系，还可以这样来看     

《地理教学》2011,(13):63-64

以银河为灵感来源,国际著名的天文艺术家、来自美国的乔恩·朗姆博格带来了他的最新创意——银河系花园,用直径30米的花园来表现直径10万光年的银河系。  相似文献   

河北省天桂山典型溶洞景观成因类型   总被引：1，自引：0，他引：1  

王健  陈琢  张梅平  黄华芳 《山地学报》2011,29(2)

河北省天桂山地区的喀斯特洞穴集中分布在早古生代寒武纪-奥陶纪碳酸盐岩地层中,多沿NW-SE、NE-SW和近S-N断裂发育.受第四纪间歇性构造抬升影响,溶洞具有成层分布特点.以溶洞景观类型为基础,将该区溶洞分为侵蚀型和堆积型两大类,分别以银河洞和珍珠洞为代表,前者多发育各种窝穴、流痕、边槽等侵蚀及坍塌景观,后者则发育各种化学堆积景观.研究溶洞景观成因类型及特征对于天桂山旅游资源的合理开发和保护具有重要指导意义.  相似文献   

Separation of Different Contributions to the Total X-ray Luminosity in Gamma-ray Loud Blazars     

Gustavo E.Romero 《中国天文和天体物理学报》2005,5(5):457-462

The relativistic beaming model has been successfully used to explain many of the observational properties of active galactic nuclei. In this model the total emission is formed by two components, one beamed, one unbeamed. However, the exact contribution from each component in unresolved sources is still not clear. In the radio band, the core and extended emissions are clearly separated. We adopt the method proposed by Kembhavi to separate the two contributions in the X-ray emissions in a sample of 19 gamma-ray loud blazars. It is clearly shown that the beamed emission dominates the X-ray flux and the unbeamed X-ray emission is correlated with the extended radio emission of the considered objects. We also find that the ratio of the beamed to the unbeamed X-ray luminosity is correlated with the X-ray spectral index, an effect that should be a consequence of the underlying X-ray emission mechanism.  相似文献   

银河系化学元素的丰度特征和合成图像(I):星际介质中轻元素丰度的观测及其特征     

侯金良 《天文学进展》1997,(4)

给出并解释了星际介质中轻元素D，3He，4He和Li的最新观测数据．星际介质中轻元素的丰度观测结果可以用来检验标准大爆炸核合成理论，因此对这些元素的丰度研究具有重要的天体物理意义．到目前为止，轻元素丰度的观测结果基本上支持开放宇宙的观点．根据最新的观测结果，在本地星际介质中D丰度可能存在小尺度不均匀性，而对类星体吸收云的观测表明不同观测者所获得的原初D丰度结果最大差别可达一个量级．如果观测是可靠的，那么在目前的标准大爆炸核合成理论和星系化学演化模型框架下还不能解释这种结果．另外种种迹象表明太阳系丰度可能不代表45亿年前本地星际介质的丰度．  相似文献   

脉冲星在银河系z方向上的演化     

赵永恒  黄克谅 《中国天文和天体物理学报》1992,(4)

本文试图确定脉冲星在银河系z方向上分布的标高与其年龄的关系。我们采用银河系引力场分布的模型,使用Monte Carlo方法随机投点,计算具有一定初始位置分布和速度分布的脉冲星的标高随年龄的演化,并同观测结果进行了比较.  相似文献