Bloated stars as AGN broad-line clouds: the emission-line spectrum
Bloated stars as AGN broad-line clouds: the emission-line spectrum
复制标题
DOI：
10.1093/mnras/270.4.781
复制
发表时间：
1994-04
影响因子：
4.8
通讯作者：
T. Alexander;H. Netzer
中科院分区：
文献类型：
--
作者：
T. Alexander;H. Netzer
膨胀恒星假说认为AGN宽线辐射起源于膨胀恒星（BS）的风或包层。与BLR云模型相比，它的主要优点是气体的引力限制，而它的主要困难是BSs的估计数量大，由此导致的质量损失率高。我们通过详细的数值光电离代码计算了大范围风结构的发射谱线和详细的QSO核模型，其中L（离子）=7E45 erg/s， M(bh)=8E7 Mo。风的大小和边界密度由各种过程决定：中心电离源的合成（自一致计算），黑洞的潮汐破坏和风的有限质量设定的极限。我们发现，发射光谱主要取决于风的线发射分数的边界条件，而不是风的内部结构。复合导致边界处的电离参数非常高，从而产生过量的未观察到的宽高激发禁线。有限质量约束限制了风的大小，增加了边界密度，从而改善了结果。具有高气体密度（1E8-1E12 cm^-3）的缓慢减速质量约束流在再现观测线方面与云一样成功。内部1/3 pc只需要5E4个密集风BSs。这一小部分接近太阳附近的超巨星（SG），质量损失与观测条件一致。BS数是风结构的一个非常敏感的函数。类sg的BSs由于其高质量损失而被排除在外。具有密集风的BSs可以复制BLR线谱，并得到恒星群的支持，而不会造成过多的质量损失和碰撞破坏率。
The Bloated Stars Scenario proposes that AGN broad line emission originates in the winds or envelopes of bloated stars (BS). Its main advantage over BLR cloud models is the gravitational confinement of the gas and its major difficulty the large estimated number of BSs and resulting high mass loss rate. We calculate the emission line spectrum by a detailed numerical photoionization code for a wide range of wind structures and a detailed QSO nucleus model with L(ion)=7E45 erg/s, M(bh)=8E7 Mo. The size and boundary density of the wind are determined by various processes: Comptonization by the central ionizing source (calculated self consistently), tidal disruption by the black hole and the limit set by the wind's finite mass. We find that the emission spectrum is mainly determined by the conditions at the boundary of the line emitting fraction of the wind rather than by its internal structure. Comptonization results in very high ionization parameters at the boundary which produces an excess of unobserved broad high excitation forbidden lines. The finite mass constraint limits the wind size, increases the boundary density and thus improves the results. Slow decelerating mass-constrained flows with high gas densities (1E8-1E12 cm^-3) are as success- ful as clouds in reproducing the observed lines. Only 5E4 dense wind BSs are required in the inner 1/3 pc. This small fraction approaches that of super- giants (SG) in the solar neighborhood and the mass loss is consistent with the observational constraints. The BS number is a very sensitive function of the wind structure. SG-like BSs are ruled out by their high mass loss. BSs with dense winds can reproduce the BLR line spectrum and be supported by the stellar population without excessive mass loss and collisional destruction rates.