The impact of magnetic fields on gas accretion onto supermassive black holes and AGN feedback: the next frontier of galaxy formation cosmological simu

现在已经很好地确定，为超大质量黑洞（SMBH）提供燃料的主要机制是磁旋转不稳定性（Balbus & Hawley 1991）。也有令人信服的观测证据表明，SMBH是无处不在的，并通过极其活跃的AGN反馈事件在调节星系属性（质量，大小，形态）方面发挥着重要作用。然而，宇宙学的星系形成模拟，总的来说，忽略了磁场的影响。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。基于我们小组以前的工作（Beckmann，Devriendt，Slyz 2018，Beckmann，Slyz & Devriendt 2019，Martin-Alvarez et al 2018，Katz，Martin-Alvarez et al 2019，Martin-Alvarez et al 2020），这个DPhil项目的目的是在明确的宇宙学背景下开发SMBH和AGN反馈的完全磁化实现。DPhil项目将有几个步骤，从重新审视经典的Bondi-Hoyle-Lyttleton吸积模型到一个点源将其磁化，将黑洞放置在一个孤立的星系盘中，在最终进入宇宙学环境之前，将AGN反馈添加到它。学生还将根据这些星系和宇宙学MHD模拟的后处理开发星系同步辐射模型，为了给即将到来的平方公里阵列仪器及其前体仪器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）。

It is now well established that the main mechanism to fuel super massive black holes (SMBH) around which a sub-parsec sized accretion disk is spinning, is the magneto-rotational instability (Balbus & Hawley 1991). There also exists compelling observational evidence that SMBHs are ubiquitous and play an important role in regulating galaxy properties (mass, size, morphology) through extremely energetic AGN feedback events. However, cosmological galaxy formation simulations, by and large, ignore the effect of magnetic fields. 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. Building on previous work within our group (Beckmann, Devriendt, Slyz 2018, Beckmann, Slyz & Devriendt 2019, Martin-Alvarez et al 2018, Katz, Martin-Alvarez et al 2019, Martin-Alvarez et al 2020), the aim of this DPhil project is to develop a fully magnetised implementation of SMBHs and AGN feedback in an explicit cosmological context. The DPhil project will have several steps starting from revisiting the classic Bondi-Hoyle-Lyttleton accretion model onto a point source to magnetize it, placing the black hole within an isolated galactic disk, adding AGN feedback to it before finally moving to the cosmological environment.The student will also develop a model for galaxy synchrotron emission based on the post-processing of these galactic and cosmological 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).