Optical/Ultraviolet Emission From Active Galactic Nuclei

AST95-29230 PI：活动星系核的光学/紫外线发射目前还不清楚活动星系核的光学/紫外光谱的起源。X射线观测表明，标准的薄吸积盘模式可以这样改变，即相当大一部分引力能量被转移和释放到盘的光学厚度部分之外，但目前还不清楚这样的模型是否能解释所有的光学/紫外观测。PI将调查两相模型(圆盘和覆盖的热晕)对光学和紫外线观测的影响，特别是集中在非LTE、自洽的大气代码将产生的光谱和偏振。该模型假定圆盘和日冕在每个半径处局部耦合，将探索由日冕中吸积功率耗散分数和日冕光学厚度定义的参数空间。还将研究紫外线/光学对X射线可变性的响应。

AST 95-29230 PI: Omer Blaes Optical/Ultraviolet Emission from active Galactic Nuclei The origin of the optical/UV spectrum in Active Galactic Nuclei is not currently understood. X-ray observations suggest that the standard thin accretion disk paradigm be altered in such a way that a substantial fraction of the gravitational energy be transferred and released outside the optically thick portion of the disk, but it is not clear that such a model can explain all the optical/UV observations. The PI will investigate the consequences of two-phase models (disk and overlying hot corona) for the optical and ultraviolet observations, concentrating in particular on the spectrum and polarization that a non-LTE, self-consistent, atmosphere code would produce. The model, which assumes that the disk and corona are locally coupled at each radius, will explore the parameter space defined by the fraction of accretion power dissipated in the corona and the coronal optical depth. The UV/optical response to X-ray variability will also be studied.