Line profiles of the two-phase medium broad-line region in active galactic nuclei  

作　　者：薛随建 林宣滨 程福臻 John Kwan 

机构地区：[1]Also in Shaanxi Astronomical Observatory.Chinese Academy of Scienocs,Lintong 710600,China. [2]The Center for Astrophysics, University of Science and Technology of China, Hefei 230026, China [3]Department of Physics and Astrophysics,University of Massachusetts,USA

出　　处：《Science China Mathematics》1996年第8期883-896,共14页中国科学：数学（英文版）

基　　金：Project supported by Pangden Project Foundation;National Natural Science Foundation of China.

摘　　要：In the framework of BLR in AGNs, i.e. large number of small, cold and dense emission-line clouds immerging in an intercloud hot medium, a delicate radiation model for a typical emission cloud is established, in which the backside photoionization of the cloud against the central continuum source by the scattered diffuse continuum in the hot medium is considered. Under the assumption of the radial kinematics of the BLR clouds, the line profiles for the two important UV emission-lines, Lya and CIV/11549 are computed; and based on these calculations, various physical factors that affect the properties of the emission-line profiles are discussed. It is concluded that: (i) when the BLR clouds is inflow, there exists a confining hot medium with density around 2 x 105 cm-3. In this case, theoretical line profiles agree well with the observational; (ii) both symmetric Lya and nearly symmetric CIV line profiles show blue velocity shifts, the quantities of which are sensitive to the cutoff of the outer radius of the BLR. It is suggested that this cutoff effect is physical background to explain the observations that high ionization lines in the spectra of AGNs have some systematic blue shifts relative to those low ionization lines which usually characterize their source system velocities.In the framework of BLR in AGNs, i.e. large number of small, cold and dense emission-line clouds immerging in an intercloud hot medium, a delicate radiation model for a typical emission cloud is established, in which the backside photoionization of the cloud against the central continuum source by the scattered diffuse continuum in the hot medium is considered. Under the assumption of the radial kinematics of the BLR clouds, the line profiles for the two important UV emission-lines, Lya and CIV/11549 are computed; and based on these calculations, various physical factors that affect the properties of the emission-line profiles are discussed. It is concluded that: (i) when the BLR clouds is inflow, there exists a confining hot medium with density around 2 x 105 cm-3. In this case, theoretical line profiles agree well with the observational; (ii) both symmetric Lya and nearly symmetric CIV line profiles show blue velocity shifts, the quantities of which are sensitive to the cutoff of the outer radius of

关 键 词：active GALACTIC NUCLEI (AGNs) BROAD LINE region (BLR) EMISSION LINE profiles. 

分 类 号：P156[天文地球—天文学]