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，它的亮度可以超过整个宿主星系。在它们被发现后的50多年里，一幅关于类星体的图片出现了，它是一个超大质量黑洞，位于或靠近一个大星系的中心。星系中的星际气体，可能是恒星在靠近黑洞的轨道上被潮汐力破坏的残留物，落入黑洞，在这个过程中被加热到非常高的温度，并在很宽的波长范围内释放出丰富的辐射。随着气体的流入，类星体也很清楚地将气体赶出了核区域。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吸收中也可以看到流出物。这些天体被称为宽吸收线类星体或BAL类星体，因为在它们的紫外光谱中可以看到轻微电离的原子种类。长期以来，人们一直认为类星体是奇怪的，但现在越来越清楚的是，当沿着某些视线观察时，许多或大多数类星体都表现出这种光谱特征。一个突出的问题是BAL流出是如何产生的。它是从离黑洞很近的地方发射出来的气体，还是从核区域以外的某个地方产生的？答案很重要，因为根据其强度，BAL风可以通过所谓的类星体反馈影响宿主星系的特性。这个项目将使用详细的光谱分析和一些BAL类星体的成像来更好地确定BAL气体的起源和它的性质。该项目将聘请一些本科生研究人员，其中许多是妇女或代表性不足的少数民族。可以说，宽吸收线流出物需要确定的最重要参数是它们与中心源的距离(R)。一个明确的答案将有很长的路要走：(A)确定这些外流是否有足够的能量来产生人们所追求的“类星体模式反馈”，理论家认为这是影响星系和星系团聚集历史的关键机制；(b)确定流出物在超大质量黑洞与宿主星系之间的联系中所起的作用；(c)允许对流出源和加速度进行逼真的建模。大多数AGN研究人员，尤其是动力学建模者，倾向于这样一种图景：BAL流出物是从AGN吸积盘发射出来的，并在其附近被观察到（R~0.01-0.1 pc）。然而，在最近的一系列论文中，首席研究员的团队测量了10个单独类星体的R到20多个流出成分，并且在每种情况下都发现R在100-10,000秒差距之间。先前假设和测量的R之间的巨大差异具有戏剧性的后果，因为流出的质量通量和动力学光度与R呈线性关系。一个突出的结果是该团队发现了迄今为止测量到的最具能量的类星体流出，具有充足的动力学光度，是AGN反馈的主要贡献者。因此，如果这些大R流是大多数BAL流出的代表，它们可以提供理论上期望的类星体模式反馈。该项目将通过观察一组异质物体，分析精心设计的调查样本，获取这些流出物的直接成像光谱，并从丰富的BAL变异性新数据集中提取R，来推进这一独特的观测和建模程序。结果应该明确地评估BAL风是否可以成为AGN反馈的主要因素。

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.