Cool cores of galaxy clusters are thought to be heated by low-power active galactic nuclei (AGN), whose accretion is regulated by feedback. However, the interaction between the hot gas ejected by the AGN and the ambient intracluster medium is extremely difficult to simulate as it involves a wide range of spatial scales and gas that is Rayleigh-Taylor (RT) unstable. Here we present a series of three-dimensional hydrodynamical simulations of a self-regulating AGN in a galaxy cluster. Our adaptive-mesh simulations include prescriptions for radiative cooling, AGN heating and a subgrid model for RT-driven turbulence, which is crucial to simulate this evolution. AGN heating is taken to be proportional to the rest-mass energy that is accreted onto the central region of the cluster. For a wide range of feedback efficiencies, the cluster regulates itself for at least several $10^9$ years. Heating balances cooling through a string of outbursts with typical recurrence times of around 80 Myrs, a timescale that depends only on global cluster properties. Under certain conditions we find central dips in the metallicity of the intracluster medium. Provided the sub-grid model used here captures all its key properties, turbulence plays an essential role in the AGN self-regulation in cluster cores.
A Chandra Study of the Radio Galaxy NGC 326: Wings, Outburst History, and AGN Feedback
NGC 326是最突出的X或Z形射电星系（XRG/ZRG）之一，并一直是几项研究的主题，试图通过流体运动或喷流轴的重新定向来解释其形态。我们研究了一个100 ks的档案钱德拉曝光，并发现与射电星系相关的几个功能：高温前，可能表明一个冲击，高温结周围的无线电发射的边缘，和一个腔与东翼的射电星系。根据射电数据对这些特征的合理解释使我们能够重建活动星系核爆发的历史。这次活跃的爆发很可能曾经是一个强大的射电源，但后来已经衰减，间接证据表明，重新定向是产生翅膀的手段。由于射电星系与ICM之间存在明显的相互作用，并且主动叶和翼之间存在很大的间隔，我们得出结论，XRG是通过测量与主动和被动加热机制相关的加热率来研究星系群中AGN反馈的极好来源。
Gas Accretion from a Neighbouring Galaxy Fuels the Low-luminosity AGN in NGC 4278
National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；Guizhou Radio Astronomical Observatory, Guizhou University（贵州大学贵州无线电天文观测站）
Radio AGN in nearby dwarf galaxies: the important role of AGN in dwarf-galaxy evolution
本文结合超超极凸轮和低频阵列（LOFAR）的深空光学和射电观测资料，对附近（z<0.5）矮星系的78个射电活动星系核进行了研究。与控制样本相比，匹配的恒星质量和红移，表明活动星系核和控制居住在类似的环境中，显示出类似的恒星形成率（跟踪气体的可用性），并表现出可比的潮汐特征的发生率（这表明最近的相互作用）。我们探索活动星系核的性质相结合的预测气体条件的矮星从宇宙流体动力学模拟与蒙特卡洛套件的模拟射电源，基于半解析模型的射电星系演化。在LOFAR可探测的模拟源子集中，其射电光度分布与我们观测到的活动星系核相似，喷流功率、年龄和吸积率的中值分别为$\sim 10^{35}$ W、$\sim 5$ Myr和$\sim 10^{-3.4}$ M $_{\odot}$ yr $^{-1}$。这些源的机械能输出中值比矮气藏中预期的结合能中值大$\sim100$倍，这使得活动星系核反馈似乎是合理的。由于活动星系核的存在并不需要特殊的环境条件（如环境、气体可用性和相互作用），而且中心气体质量被预测为比活动星系核所需的燃料大一个数量级，因此活动星系核在矮星系中的触发可能是随机的，是一种普遍现象。再加上能量反馈的不确定性，这表明活动星系核可能是矮星系演化的重要驱动力，就像大质量星系一样。
Chandra X-ray and Hubble Space Telescope Imaging of Optically Selected Kiloparsec-Scale Binary Active Galactic Nuclei II: Host Galaxy Morphology and AGN Activity
Separating the Optical to Near-Infrared Light of AGN and Their Host Galaxies
Department of Physics & Astronomy, The University of Western Ontario（韦仕敦大学物理与天文系）；Institute for Earth & Space Exploration, The University of Western Ontario（韦仕敦大学地球与太空探索研究所）
Tracing AGN-Galaxy Co-Evolution with UV Line-Selected Obscured AGN
University of Cape Town（开普敦大学）；Inter-University Institute for Data Intensive Astronomy, Department of Astronomy, University of Cape Town（开普敦大学天文学系跨大学数据密集型天体物理研究所）；INAF - Istituto di Radioastronomia（意大利国家天体物理研究所射电天文台）；Inter-University Institute for Data Intensive Astronomy, Department of Physics and Astronomy, University of the Western Cape（西开普大学物理与天文学系跨大学数据密集型天体物理研究所）；Dipartimento di Fisica e Astronomia “Augusto Righi”, Università degli Studi di Bologna（博洛尼亚大学“奥古斯托·里吉”物理与天文学系）；INAF-OAS, Osservatorio di Astrofisica e Scienza dello Spazio di Bologna（意大利国家天体物理研究所博洛尼亚天体物理学与空间科学观测站）；Instituto de Astrofísíca e Ciências do Espaço, Faculdade de Ciências, Universidade de Lisboa（里斯本大学理学院空间科学与天体物理研究所）；Astronomy and Astrophysics division, Physical Research Laboratory（物理研究实验室天文与天体物理部）；Astrophysics, Department of Physics, University of Oxford（牛津大学物理系天体物理学组）；Institute for Astronomy, University of Edinburgh（爱丁堡大学天体物理研究所）；Department of Physics and Electronics, Rhodes University（罗德岛大学物理与电子学系）；South African Radio Astronomy Observatory（南非射电天文观测台）；Department of Physics and Astronomy, University of the Western Cape（西开普大学物理与天文学系）
