A Multiwavelength Study of the Physics of the Intracluster Medium, Its Multiple Phases and AGN Feedback

星系团是宇宙中最大的引力约束结构。与占主导地位的暗物质不同，重子物质可以直接观察到。它以恒星和一种被称为ICM的炽热稀薄气体的形式存在于各个星系中，充满了星系之间的空间。当ICM冷却时，它在光谱的x射线部分辐射。如果没有人看管，它将继续冷却，在紫外线、光学和红外线中辐射。最终，气体应该冷却到几十度，并被束缚在巨大的分子气云中，然后坍塌形成恒星。在一个丰富的星系团的中心坐落着一个巨大明亮的椭圆星系--最亮的星系团星系(BCG)，它的核心包含一个超大质量的黑洞(SMBH)。人们认为，SMBH向ICM重新提供能量，因为从ICM凝结的一些冷气体落到黑洞周围的吸积盘上，最终增加了黑洞的质量，并助长了强大的外流。这种外流将能量、磁场和相对论电子带入ICM，在那里它可以重新供应通过辐射损失的能量。最近用射电和X射线望远镜进行的观测提供了新的高质量图像，显示了流出的洞穴和驱动压力波进入ICM的情况。因此，很明显，在冷却和加热、流入和流出、吸积和生长之间存在着复杂的相互作用。今天在星系团中运行的相同物理过程很可能发生在50-100亿年前的星系形成期间。天文学家认为，银河系及其中心黑洞的增长是通过反馈过程耦合的。介质、星系生长和中央黑洞之间的反馈必须运行数十亿年，大小从几秒到几十万秒。因此，ICM是一个动态的地方，加热和冷却过程争夺主导地位，超大质量黑洞在星系中心生长，并维持一种不稳定的平衡。这项工作的主要目标是通过对工作中的物理过程进行详细的理解，揭示反馈机制是如何在集群中心运行的。利用我的NSERC发现基金，我将对附近的星系团进行多波长观测研究，以绘制重子物质的空间、热和时间演化图，确定系统能量学，并确定起作用的主要反馈回路。从高中到博士后，我们将与4名HQP一起工作，我们将组装这些复杂系统中重子物质每一阶段的空间分布、运动学、质量含量和能量学的详细图像。影响：这项工作将产生我们和其他天文学家用来发展我们对支配星系团和星系演化的反馈机制和宏观进化规律的理解的信息。

Clusters of galaxies are the largest gravitationally bound structures in the Universe. Baryonic matter, unlike the dominant dark matter, is accessible to direct observations. It is found within individual galaxies as stars and as a hot tenuous gas, dubbed the ICM, filling the space between galaxies. As the ICM cools it radiates in the x-ray part of the spectrum. Left unattended it will continue to cool, radiating in the ultraviolet, optical, and infrared. Ultimately the gas should cool to tens of degrees and be bound in giant molecular gas clouds that collapse to form stars. At the center of a rich cluster sits a massive bright elliptical galaxy, the Brightest Cluster Galaxy (BCG), which houses a super-massive Black Hole (SMBH) at its nucleus. It is believed that the SMBH re-supplies energy to the ICM as some of the cold gas that condenses from the ICM falls onto an accretion disk around the Black Hole, ultimately adding to the mass of the Black Hole and fuelling the ejection of a powerful outflow. This outflow carries energy, magnetic fields, and relativistic electrons into the ICM where it can re-supply energy lost through radiation. Recent observations with radio and X-ray telescopes have provided new high quality images showing the outflow excavating cavities and driving pressure waves into the ICM. Thus it is clear a complex interplay exists between cooling and heating, inflow and outflow, accretion and growth. The same physical processes operating in clusters today likely occurred during galaxy formation 5-10 billion years ago. Astronomers believe that the growth of the galaxy and its central black hole are coupled via feedback process. The feedback between the medium, galaxy growth, and the central black hole must operate over billions of years, and on size scales from parsecs to hundred of thousands of parsecs. Thus, the ICM is a dynamic place where heating and cooling processes vie for dominance, super-massive black holes grow at the centers of galaxies, and an uneasy equilibrium is maintained. The major objective of this work is to uncover how feedback mechanisms operate in the centers of clusters by developing a detailed understanding of the physical processes at work. With my NSERC Discovery grant, I will conduct a multi-wavelength observational study of nearby clusters, to map the spatial, thermal, and temporal evolution of the baryonic matter, determine the system energetics, and identify the dominant feedback loops at play. Working with 4 HQP from high school through postdoc, we will have assembled a detailed picture of the spatial distribution, kinematics, mass content, and energetics of each phase of the baryonic matter in these complex systems. Impact: this work will create the information that we and other astronomers use to develop our understanding of the feedback mechanisms and macro-evolutionary laws that govern cluster and galaxy evolution.