The role played by super massive black holes in magnetizing the circum-galactic medium

超大质量黑洞在磁化环绕银河系介质中所起的作用

• 批准号: 2285832
• 金额: --
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2285832
• 关键词: role; played; super; massive; black

The circum-galactic medium (CGM) holds the key to galaxy formation and evolution as it provides direct constrains on the stellar and supermassive black hole (SMBH) feedback processes widely believed to regulate galaxy global properties (mass, size, morphology). Yet, detailed numerical hydrodynamics simulations designed to capture these feedback processes have so far failed to produce a CGM which matches that observed around high-redshift galaxies. Presumably this failure reflects the fact that star formation and stellar feedback, and SMBH formation, accretion and feedback, take place on extremely small, sub-galactic scales, making it a tremendous challenge for simulations to model them with reasonable accuracy whilst resolving the galaxy larger scale environment at the same time. Thanks to a super Lagrangian refinement technique specifically tuned to increase numerical resolution in the CGM, coupled to an accurate radiative transfer method to self-consistently follow the interaction of ionising photons with the gas, the NEPHTHYS suite of cosmological zoom simulations we have recently embarked upon has started to remedy the situation. Indeed, such an approach has, for the first time, revealed a richness of features in the CGM comparable to that observed. On the other hand, important physics is still missing from the simulations. In particular, the impact of magnetic fields --- which are measured to be in equipartition with thermal and turbulent energy in the interstellar medium of galaxies --- on the structure of the CGM remains uncharted territory. Meanwhile, theoretical predictions regarding the role these fields play in shaping galaxy evolution will undoubtedly be required to help make sense of the unprecedentedly deep radio data soon to revolutionize the field. The DPhil project therefore consists of two stages. At first, the student will expand the NEPHTHYS suite of high-resolution cosmological simulations targetting the CGM of massive galaxies, by running their MHD counterpart and including SMBH accretion and feedback, building upon state-of-the-art algorithms previously developed within our group. Secondly, they will develop their own model for galaxy synchrotron emission based on the post-processing of these MHD simulations, in a view to produce realistic mock observational data for the coming Square Kilometer Array instrument and its precursors (in interaction with the radio astronomy observational group at Oxford centred around Prof. Jarvis). This research falls within STFC's science programme challenge A: How did the Universe begin and how it is evolving?, and more specifically sub-challenges A.4: When and how were the first stars, black holes and galaxies born? and A.5: How do stars and galaxies evolve?

环星系介质（CGM）是星系形成和演化的关键，因为它对恒星和超大质量黑洞（SMBH）的反馈过程提供了直接的约束，广泛认为这些反馈过程可以调节星系的整体性质（质量，大小，形态）。然而，详细的数值流体动力学模拟设计来捕捉这些反馈过程，迄今未能产生一个CGM匹配，观察高红移星系周围。据推测，这一失败反映了这样一个事实，即星星的形成和恒星反馈，以及SMBH的形成，吸积和反馈，发生在非常小的，亚星系尺度，使其成为一个巨大的挑战，模拟以合理的精度，同时解决星系更大规模的环境。得益于专门用于提高CGM数值分辨率的超级拉格朗日细化技术，再加上精确的辐射传输方法来自洽地跟踪电离光子与气体的相互作用，我们最近开始的NEPHTHYS宇宙学变焦模拟套件已经开始纠正这种情况。事实上，这样的方法，第一次，揭示了丰富的功能，在CGM相比，所观察到的。另一方面，模拟中仍然缺少重要的物理学。特别是，磁场的影响-这是测量到在星系的星际介质中的热能和湍流能均分-对CGM的结构仍然是未知的领域。与此同时，关于这些场在塑造星系演化中所起作用的理论预测无疑将有助于理解前所未有的深度无线电数据，这些数据将很快使该领域发生革命性变化。因此，哲学博士项目包括两个阶段。首先，学生将通过运行MHD对应物并包括SMBH吸积和反馈，扩展NEPHTHYS高分辨率宇宙学模拟套件，以大规模星系的CGM为目标，建立在我们小组以前开发的最先进的算法基础上。第二，他们将根据这些磁流体动力学模拟的后处理，开发自己的星系同步辐射模型，以便为即将到来的平方公里阵列仪器及其前体提供真实的模拟观测数据（与以Jarvis教授为中心的牛津射电天文学观测小组进行互动）。这项研究福尔斯属于STFC的科学计划挑战A：宇宙是如何开始的，它是如何演变的？，更具体地说，子挑战A.4：第一颗恒星、黑洞和星系是何时以及如何诞生的？和A.5：恒星和星系是如何演化的？