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）。超大质量黑洞（SMBH）的周围有一个次秒差距大小的吸积盘在旋转。也有令人信服的观测证据表明，SMBHs无处不在，并且通过极其高能的AGN反馈事件在调节星系特性（质量、大小、形态）方面发挥着重要作用。然而，总的来说，宇宙星系形成模拟忽略了磁场的影响。这种失败可能反映了这样一个事实，即恒星形成和恒星反馈，以及SMBH的形成、吸积和反馈，都发生在极小的亚星系尺度上，这使得在解决星系更大尺度环境的同时，以合理的精度对它们进行模拟是一个巨大的挑战。基于我们小组之前的工作（Beckmann, Devriendt, Slyz 2018, Beckmann, Slyz & Devriendt 2019， Martin-Alvarez等人2018，Katz， Martin-Alvarez等人2019，Martin-Alvarez等人2020），本博士项目的目标是在明确的宇宙学背景下开发SMBHs和AGN反馈的全磁化实现。博士项目将有几个步骤，从重新审视经典的邦迪-霍伊尔-利特尔顿吸积模型到一个点源磁化它，把黑洞放在一个孤立的星系盘中，在最后移动到宇宙环境之前给它添加AGN反馈。该学生还将基于这些星系和宇宙学MHD模拟的后处理开发一个星系同步辐射模型，以期为即将到来的平方公里阵列仪器及其前体产生真实的模拟观测数据（与牛津大学以Jarvis教授为中心的射电天文观测小组互动）。

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).