Black holes: sculptors of galaxies

现代天体物理学中最令人着迷的发现之一是认识到所有大质量星系的中心都有一个黑洞--这些黑洞可以是巨大的，质量随时可以超过100万个太阳质量。**当一个这样的黑洞积极地从周围吸积物质时，它可能会表现出看似混乱的性质。特别是，它可以变得如此明亮，以至于让它的宿主星系黯然失色，它还可以驱动强大的外流，这些外流往往远远超出银河系的宿主。流入的吸积物质与通过辐射和流出释放的能量之间的相互作用(称为黑洞反馈)，在塑造黑洞周围环境，最终塑造宿主星系本身方面发挥着基础性作用。然而，这种交流背后的细节仍然鲜为人知。因此，辨别这一基本过程的性质是现代天体物理学研究的前沿课题。**拟议的计划旨在显著提高我们对大质量星系中黑洞反馈的理解。最终目标是建立这样一个反馈模型，然后将其作为宇宙学模拟的基本输入。为了做到这一点，我们已经建立了一个广泛的初步样本，包括大范围的具有黑洞外流的大质量星系(&gt；100个天体)。这个样本的范围从贫瘠的孤立星系到已知的最大质量的星系：那些发现在星系团中心的星系。这些星系都有由中央黑洞流出形成的“X射线空洞”形式的外流。“X射线空洞”是一个巨大的坑，在大质量星系周围的热晕中耗尽了发射X射线的气体。这种有针对性的系统为评估黑洞对其周围环境的影响提供了充足的证据。特别是，X射线腔提供了与黑洞反馈相关的能量的干净估计；这是通过直接计算充气所需的能量来确定的。通过利用这个样本，我们将解决三个关键问题，长期目标是建立一个描述这种反馈如何在大质量星系中运行的模型-一个将极大地造福于河外科学界的模型：**(1)我们将确定导致黑洞外流的物理过程是否依赖于星系质量。这涉及到一些问题，比如，较小星系中的流出实际上是在较大质量星系中发现的流出的缩小版本吗？若否，原因为何？活动星系核外流如何依赖于环境效应或其所在星系的性质？**(2)我们将确定黑洞反馈是否能够以及如何通过将富含金属的气体抬升到所在星系的边界之外来丰富星际介质。这将通过研究外流周围的元素丰度来实现。量化活动星系核反馈在重新分配富含金属的气体中所起的作用，对于我们对星系如何形成和演化的一般理解至关重要。**(3)我们最终将研究直接由黑洞产生的辐射性质，为黑洞的爆发提供动力。这包括在我们之前在黑洞活动的基本平面上的工作的基础上，建立X射线光度、射电光度和黑洞质量之间的既定关系，以及首次建立这些物体的光谱能量分布。**该计划将使我们对黑洞物理有大致的了解，并与河外天体物理和宇宙学有关。

One of the most fascinating discoveries in modern astrophysics has been the realization that all massive galaxies harbor a black hole at their centers - and that these black holes can be colossal, with masses readily exceeding a million Solar masses.**When one such black hole is actively accreting matter from its surroundings, it can exhibit seemingly confounding properties. In particular, it can become so luminous as to outshine its host galaxy, and it can drive powerful outflows that often extend well beyond the galactic host. The interplay between the inflowing accreting matter versus the energy released through radiation and outflows (known as black hole feedback), plays a fundamental role in sculpting the surrounding environment of the black hole, and ultimately the host galaxy itself. Yet the details behind this exchange remain poorly understood. Accordingly, discerning the nature of this fundamental process is a forefront topic of research in modern astrophysics.**The proposed program aims to significantly advance our understanding of black hole feedback in massive galaxies. The ultimate goal is to build a model of such feedback, which can then serve as a fundamental input for cosmological simulations. To accomplish this, we have built an extensive preliminary sample that encompasses a large range of massive galaxies with black hole outflows (>100 objects). This sample ranges from anemic isolated galaxies to the most massive galaxies known: those found at the centers of clusters of galaxies. These systems all have outflows in the form of "X-ray cavities" - gargantuan pits which are depleted of X-ray-emitting gas in the hot halos that surround massive galaxies - carved out by the outflows of the central black hole. Such targeted systems provide ample evidence in assessing the impact black holes have on their surrounding environment. In particular, X-ray cavities provide clean estimates for the energetics associated with black hole feedback; this is determined via straightforward calculations of the energy required to inflate them. By utilizing this sample, we will solve three key issues, with the long-term goal of building a model that describes how this feedback operates in massive galaxies - a model that will significantly benefit the extragalactic scientific community:**(1) We will determine if the physical processes giving rise to black hole outflows are dependent upon galaxy mass. This touches upon questions such as, are outflows in smaller galaxies actually scaled-down versions of those found in the more massive systems? If not, why? How do AGN outflows depend on environmental effects or on the properties of their host galaxies?**(2) We will determine if and how black hole feedback is capable of enriching the intergalactic medium by uplifting metal-rich gas beyond the confines of the host galaxies. This will be achieved by studying the elemental abundances surrounding the outflows. Quantifying the role AGN feedback plays in redistributing metal-rich gas, is vital to our general understanding of how galaxies form and evolve.**(3) We will finally study the radiative properties directly arising from the black holes, providing insight into the black holes that power the outbursts. This includes building on our previous work on the fundamental plane of black hole activity, an established relation between X-ray luminosity, radio luminosity, and black hole mass, as well as building for the first time spectral energy distributions for these objects. **The program will inform our general understanding of black hole physics, as well as have bearing in extragalactic astrophysics and cosmology.