Understanding the origin of AGN absorption line profiles and their diversity could help to explain the physical structure of the accretion flow, and also to assess the impact of accretion on the evolution of the AGN host galaxies. Here we present our first attempt to systematically address the issue of the origin of the complexities observed in absorption profiles. Using a simple method, we compute absorption line profiles against a continuum point source for several simulations of accretion disk winds. We investigate the geometrical, ionization, and dynamical effects on the absorption line shapes. We find that significant complexity and diversity of the absorption line profile shapes can be produced by the non-monotonic distribution of the wind velocity, density, and ionization state. Non-monotonic distributions of such quantities are present even in steady-state, smooth disk winds, and naturally lead to the formation of multiple and detached absorption troughs. These results demonstrate that the part of a wind where an absorption line is formed is not representative of the entire wind. Thus, the information contained in the absorption line is incomplete if not even insufficient to well estimate gross properties of the wind such as the total mass and energy fluxes. In addition, the highly dynamical nature of certain portions of disk winds can have important effects on the estimates of the wind properties. For example, the mass outflow rates can be off up to two orders of magnitude with respect to estimates based on a spherically symmetric, homogeneous, constant velocity wind.
The physics of galactic winds driven by active galactic nuclei
活动星系核（AGN）在其宿主星系的星际介质中驱动快速风。一般认为，星系核中的高密度和强辐射场意味着冷却时间短，因此使外流动量守恒。我们发现，在AGN的高速，冲击风的冷却实际上是在很大范围的情况下，包括超亮红外星系（ULIRGs）的相关条件下，在节能外流效率低下。我们进一步表明，快速节能外流可以容忍大量的混合与冷却气体之前，辐射损失变得重要。对于初速度v_in>~ 10，000 km·s^-1的风，正如紫外线和X射线吸收所观察到的那样，激波形成了一种双温结构。虽然大部分的热压支持是由质子提供的，但冷却过程只直接作用于电子。这显著减慢了逆康普顿冷却，而自由冷却可以忽略不计。v_in约为1，000 km s^-1的低速风，例如可能由尘埃上的辐射压力驱动的低速风，也可以经历能量守恒阶段，但条件更为严格。在能量守恒阶段，激波后热气体的做功使外流的动量通量增加了~v_in/2v_s，其中v_s是后掠物质的速度。因此，由快速活动星系核风（v_in~0.1c）驱动的能量守恒外流可以解释最近在亮类星体和ULIRGs中测量到的星系尺度外流的动量通量Pdot>>L_AGN/c。冲击风泡在星系盘的法线方向上膨胀，也可以解释在某些系统中观察到的大规模双极结构，包括银河系中心周围，并且可以产生显著的无线电，X射线和伽马射线发射。[删节]
Metal enrichment by radiation pressure in active galactic nucleus outflows -- theory and observations
活动星系核的外流可能是由丰富的金属离子的紫外共振线吸收连续辐射产生的，如在宽吸收线类星体（BALQ）中所观察到的。施加在金属离子上的辐射压力通过金属离子的库仑碰撞耦合到气体的其余部分。我们计算的光子密度和气体密度，使去耦的金属离子从其余的气体。这些条件可导致主要由金属离子组成的流出物。基于Ly α和Si iv λλ1394，1403的吸收曲线，我们导出了一种限制金属/H比的方法.我们将这种方法应用于BALQs的SDSS样本中，以获得少数具有高于太阳能金属/H比率的候选流出物。如果存在具有强吸收边的连续源的屏蔽，则这种机制可以产生超快的UV流出。
The limits of feedback from active galactic nuclei
Institute for Computational Cosmology, Department of Physics, Durham University（达勒姆大学物理学院计算宇宙学研究所）；Institute of Astronomy and Kavli Institute for Cosmology, University of Cambridge（剑桥大学天体物理与卡弗里宇宙学研究所）；Cavendish Laboratory, Department of Physics, University of Cambridge（剑桥大学物理学院卡文迪许实验室）；The Oskar Klein Centre, Department of Physics, Stockholm University（斯德哥尔摩大学物理学院奥斯卡·克莱因中心）；Leiden Observatory, Leiden University（莱顿大学莱顿天文台）；Lorentz Institute for Theoretical Physics, Leiden University（莱顿大学洛伦兹理论物理研究所）
