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Line profiles of the two-phase medium broad-line region in active galactic nuclei
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作者 薛随建 林宣滨 +1 位作者 程福臻 John Kwan 《Science China Mathematics》 SCIE 1996年第8期883-896,共14页
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 ... 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. 展开更多
关键词 active GALACTIC NUCLEI (agns) BROAD LINE region (blr) EMISSION LINE profiles.
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Kinematic Models of BLR Gas and Line Profiles of HeIλ5876 and Hβ in AGNs
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作者 薛随建 程福臻 John Kwan 《Science China Mathematics》 SCIE 1994年第4期487-496,共10页
The present paper derives the modified expression of broad emission line profiles for the kinematic model of radiation pressure driving BLR gas outflow in the BLR, and discusses the intrinsic emission difference betwe... The present paper derives the modified expression of broad emission line profiles for the kinematic model of radiation pressure driving BLR gas outflow in the BLR, and discusses the intrinsic emission difference between the two lines HeIλ5876 and Hβ. It is shown that the fact that the observed line width of HeIλ5876 is broader than that of Hβ cannot be explained by W. G. Mathews’ modified model. For comparison, line profiles of gravitational infall model and orbital disk model are also calculated; the latter is in good agreement with the observations. Thereupon, conclusion is reached that gravitational infall is an important process in the BLR gas motion. 展开更多
关键词 agns broad-line region (blr) broad-line profiles.
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