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arXiv 1302.0201astro-ph.CO
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类星体外流的物理和物理性质

The Physics and Physical Properties of Quasar Outflows

Fred Hamann, Daniel Capellupo, George Chartas, Sean McGraw, Paola Rodriguez Hidalgo, Joseph Shields, Jane Charlton, Michael Eracleous

摘要:

我们描述了两个研究,旨在表征总柱密度,动能,和加速物理的宽吸收线(BAL)流出类星体。第一项研究使用新的钱德拉X射线和地面静止框架紫外线观测7个类星体与迷你BAL在极高的速度,在0.1c至0.2c的范围内,以测试的想法,需要强大的辐射屏蔽来缓和迷你BAL电离,并促进其加速到极端速度。我们发现,X射线吸收很弱或不存在,通常N_H <几个x 10^22 mc^-2,辐射屏蔽并不重要。我们认为,微型BAL电离是由小流出子结构中n_H ~ 4 x 10^8 cm^-3量级的高气体密度控制的。如果我们保守地假设微型BAL气体中的总柱密度为N_H < 10^22 cm^-2,沿着我们的视线(基于测得的谱线深度)覆盖>15%的紫外连续光源,那么这些流出物的径向厚度仅为Delta_R < 3 x 10^13 cm,横向尺寸> 8 x 10^15 cm。因此,流出区的形状非常薄的“煎饼”看起来正面,或他们占据较大的体积像一个喷雾的密集的小云粒与一个非常小的体积填充因子。我们推测,这种情况(与无效的屏蔽和小的密集流出子结构)适用于大多数类星体的外流,包括BALs。我们的第二项研究关注低丰度离子的BALs,主要是PV 1118、1128 A,它们的显著强度意味着较大的柱密度,NH> 10^22 cm^-2,这可能进一步挑战外流加速模型。尽管在Ly-alpha森林中很难找到这条线,但通过对SDSS DR 9类星体目录的搜索,我们发现了超过50个红移z>2.3的BAL源,具有强PV BALs,我们现在正在使用它们来表征高柱流出的一般性质。

英文摘要:

We describe two studies designed to characterize the total column densities, kinetic energies, and acceleration physics of broad absorption line (BAL) outflows in quasars. The first study uses new Chandra X-ray and ground-based rest-frame UV observations of 7 quasars with mini-BALs at extreme high speeds, in the range 0.1c to 0.2c, to test the idea that strong radiative shielding is needed to moderate the mini-BAL ionizations and facilitate their acceleration to extreme speeds. We find that the X-ray absorption is weak or absent, with generally N_H < few x 10^22 mc^-2, and that radiative shielding is not important. We argue that the mini-BAL ionizations are controlled, instead, by high gas densities of order n_H ~ 4 x 10^8 cm^-3 in small outflow substructures. If we conservatively assume that the total column density in the mini-BAL gas is N_H < 10^22 cm^-2, covering >15% of the UV continuum source along our lines of sight (based on measured line depths), then the radial thickness of these outflows is only Delta_R < 3 x 10^13 cm and their transverse size is > 8 x 10^15 cm. Thus the outflow regions have the shape of very thin "pancakes" viewed face-on, or they occupy larger volumes like a spray of dense cloudlets with a very small volume filling factor. We speculate that this situation (with ineffective shielding and small dense outflow substructures) applies to most quasar outflows, including BALs. Our second study focuses from BALs of low-abundance ions, mainly PV 1118,1128 A, whose significant strengths imply large column densities, N_H > 10^22 cm^-2, that can further challenge models of the outflow acceleration. In spite of the difficulties of finding this line in the Ly-alpha forest, a search through the SDSS DR9 quasar catalog reveals >50 BAL sources at redshifts z>2.3 with strong PV BALs, which we are now using to characterize the general properties of high-column outflows.

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