窄线SeyfertⅠ型星系  

NARROW-LINE SEYFERT Ⅰ GALAXIES

作　　者：赵崇山[1] 周又元[1] 

机构地区：[1]中国科学技术大学天体物理中心

出　　处：《物理学进展》2002年第3期249-264,共16页Progress In Physics

基　　金：973项目"星系的形成与演化"资助 (G1 9990 75 4 );国家自然基金资助项目( 1 99730 0 1 ;1 98630 0 1 )

摘　　要：本文将概述窄线SeyfertⅠ型星系 (包括具有类似性质但光度较大的类星体 )的主要观测特征、物理内涵及其理论解释和在活动星系核内部结构上的反映。窄线SeyfertⅠ型星系 (NLS1 ,以后NLS1都认为包括NLSI星系和NLS1类星体 )具有窄的允许线Hβ,它兼有Sy1和Sy2的某些特征。它具有强的FeⅡ光学线和弱的 [OⅢ ]λ5 0 0 7禁线 ,这明显不同于Sy2。在观测相关量的主成分统计分析中表明NLS1是活动星系核第一主向量表现为极端的一类。这包括 :( 1 )HβFWHM取极小 ;( 2 )FeⅡλ45 70 /Hβ 取极大 ;( 3)SⅢ ]λ1 892 /CⅢ ]λ1 90 9取极大 ,亦一定范围内宽线区电子密度取大值 ;( 4 )CⅣλ1 5 4 9线中心蓝移取极大 ;( 5 )高光度NLS1的软X射线光子数谱指数Γx 取极大 ;( 6)X射线相对流量变化方差最大等。基于以上观测结构和相应统计规律 (观测量与HβFWHM的关系 ) ,解释NLS1现象最佳的模型是高相对吸积率L/LEdd模型。NLS1比之典型宽线活动星系核具有较低的中心黑洞质量MBH。进一步 ,还发现这一模型是活动星系核主导物理参量L/MBH的直接结果 ;另一方面 ,由于活动星系核结构的非球对性 ,可能引起速度分布的各向异性 ,这是视角效应模型的基础。在与观测对比中发现视向效应是不可少的 ,但不可能解释全部观测 。We summarized the main observational properties of Narrow_line Seyfert Galaxies(Including more luminous QSOs). Thereafter, we discuss their physical implications, the theoretic interpretations and the indications on the inner structures of Active Galactic Nuclei(AGNs). Narrow_line Serfert Galaxies(NLS1s) are identified as the Narrow Hβ permitted emission lines in their optical spectra, in which the properties of Seyfert Ⅰ and Ⅱ galaxies are presented partically. NLS1s with the strongest optical FeⅡ line blends and weak forbidden lines, obviously differ from SeyfertⅡ galaxies. Classified as the subclass of normal Seyfert Ⅰ galaxies, NLS1s have the extreme properties of the observational parameters in Principal Components Analysis(PCA). Therefore, they are the primary objects to understand the characteristics and structures of board emission line region and the innermost machines surrounding the central black hole. By means of PCA,NLSI s locate in the extreme end of the Board_line AGNs, such as (1)the narrowest H β line, (2)the largest ratio of Fe Ⅱλ4507/ H β , (3)the largest ratio of Si Ⅲ]λ1892/C Ⅲ]λ1909 indicating electron density of board line clouds in a certain range, (4)the largest C Ⅳλ1549 emission line blueshift, (5)the steepest soft X ray photon spectrum index, (6)the giant amplitude of the soft X ray excess variance. Following the above observational properties and statistical analysis results ( H β FWHM vs. other observation quantities), we comment that the L/L Edd model is the best interpretation. As the prediction of this model, NLS1s have a reasonably estimate of the low black hole masses. On the other hand, the non_spherical structure of AGNs possibly rises the anisotropic velocitis dispersion. The orientation effect can not be neglected when we try to build the kinetic model of NLS1s. The high accretion rate model with the orientation effect should let us to understand the dominant emission mechanism of AGNs and its influence on the observational

关 键 词：窄线Seryfert Ⅰ Seryfet型星系 活动星系核 射电性质 紫外发射线性质 

分 类 号：P157.7[天文地球—天文学] P158