Where are the Broad Absorption Line Outflows Situated and How Important are they to Active Galactic Nuclei Feedback?

类星体是宇宙中最明亮的物体。活动星系核(AGN)是类星体的动力源，可以让整个宿主星系黯然失色。在它们被发现后的50多年里，出现了一幅类星体的图片，它是一个居住在大星系中心或附近的超大质量黑洞。银河系中的星际气体，可能是恒星在接近黑洞的轨道上运行时受到潮汐作用力破坏的残留物，落入黑洞，在这样做的过程中被加热到非常高的温度，并在广泛的波长范围内发射出丰富的辐射。在气体流入的同时，类星体将气体赶出核区也是显而易见的。少数类星体发射的物质喷流证明了这一点，但在许多类星体的光谱中也可以看到吸收中的外流。这些天体被称为宽吸收线类星体或BAL类星体，因为在它们的紫外线光谱中可以看到温和电离的原子物种具有广泛的光谱特征。长期以来，类星体一直被认为是奇怪的，但现在越来越清楚的是，当沿着特定的视线观察时，许多或大多数类星体表现出这样的光谱特征。一个悬而未决的问题是，BAL资金外流是如何产生的。它是从离黑洞非常近的地方发射的气体，还是从核区以外的某个地方发出的气体？答案很重要，因为BAL风可以通过所谓的类星体反馈影响宿主星系的性质，这取决于它的强度。该项目将使用一些BAL类星体的详细光谱分析和成像来更好地确定BAL气体的来源及其性质。该项目将雇用一些本科生研究人员，其中许多是女性或代表性不足的少数民族。可以想见，对于广泛的吸收线流出，需要确定的最重要的参数是他们到中心源(R)的距离。一个明确的答案将有很长的路要走：(A)确定这些外流是否足够能量来产生所寻求的“类星体模式反馈”，这被理论家认为是影响星系和星系团组装历史的关键机制；(B)确定外流在超大质量黑洞和宿主星系之间的联系中的作用；(C)允许对外流的起源和加速进行现实的建模。大多数活动星系核研究人员，特别是动力学模型者，倾向于一幅从活动星系核吸积盘发射并在其附近(R~0.01-0.1pc)观测到BAL外流的图像。然而，在最近的一系列论文中，首席研究员团队测量了10个类星体中20多个流出成分的R，并在每个案例中发现R在100-10,000秒之间。之前假设的R和测量的R之间的巨大差异具有显著的后果，因为流出的质量通量和动力学光度与R线性相关。一个突出的结果是该团队发现了迄今为止测量到的能量最高的类星体外流，充足的动力学光度是活动星系核反馈的主要贡献。因此，如果这些大的R流代表了大多数BAL外流，它们就可以提供理论上所需的类星体模式反馈。该项目将通过观察一组不同的物体来推进这一独特的观测和建模计划，以在精心设计的调查中分析样本，获取这些流出的直接成像光谱，并从丰富的BAL变异性新数据集中提取R。这一结果应该最终评估BAL风是否可以成为AGN反馈的主导因素。

Quasars are the most luminous objects in the universe. The active galactic nucleus (AGN) that is the quasar's powerhouse can outshine its entire host galaxy. In the more than fifty years since their discovery, a picture has emerged of a quasar as a supermassive black hole residing at or near the center of a large galaxy. Interstellar gas in the galaxy, perhaps the residue of stars disrupted by tidal forces as they orbit close to the black hole, falls into the black hole and in doing so is heated to very high temperatures and emits copious radiation over a wide range of wavelengths. Along with the gas inflow, it is also clear that quasars drive gas out of the nuclear region. This is evidenced by jets of material emitted by a minority of quasars but also by an outflow seen in absorption in the spectra of many quasars. These objects are called broad absorption line quasars or BAL quasars in reference to the broad spectral features due to mildly-ionized atomic species seen in their ultraviolet spectra. Long thought to be oddities, it is becoming clear that many or most quasars demonstrate such spectral features when viewed along certain lines of sight. An outstanding question is how the BAL outflow is generated. Is it gas that is launched from very near the black hole or is its genesis from somewhere outside of the nuclear region? The answer is important because, depending on its strength, the BAL wind can affect the properties of the host galaxy through so-called quasar feedback. This project will use detailed spectral analysis and imaging of a number of BAL quasars to better determine where the BAL gas originates and what its properties are. The project will engage a number of undergraduate researchers many of whom are women or underrepresented minorities.Arguably the most important parameter to be determined for broad absorption line outflows is their distance from the central source (R). A definitive answer will go a long way to: (a) determine whether these outflows are energetic enough to generate the sought after "quasar mode feedback," which is suggested by theorists to be a key mechanism for influencing the assembly history of galaxies and clusters; (b) establish the role of the outflows in the connection between the supermassive black hole and the host galaxy; (c) allow for realistic modeling of the outflow's origin and acceleration. Most AGN researchers and especially dynamical modelers, favor a picture where BAL outflows are launched from the AGN accretion disc and are observed in its vicinity (R~0.01-0.1 pc). However, in a recent series of papers the principal investigator's team measured R to more than 20 outflow components in 10 individual quasars and in every case found R to be between 100-10,000 parsecs. The large difference between the previously assumed and measured R has dramatic consequences since the outflow's mass flux and kinetic luminosity are linearly dependent on R. A prominent result was the team's finding of the most energetic quasar outflow measured to date, with ample kinetic luminosity to be a major contributor to AGN feedback. Therefore, if these large R flows are representative of most BAL outflows, they can supply the theoretically desired quasar mode feedback. This project will advance this unique observational and modeling program by observing a heterogeneous set of objects, to analyzing samples in well-designed surveys, acquiring direct imaging spectroscopy of these outflows, and extracting R from rich new data sets of BAL variability. The result should definitively assess whether BAL winds can be a dominant agent of AGN feedback.