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，亚帕秒大小的吸积盘围绕着超大质量黑洞(SMBH)旋转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，SMBHs无处不在，并通过极高能量的活动星系核反馈事件在调节星系属性(质量、大小、形态)方面发挥重要作用。然而，宇宙星系形成的模拟大体上忽略了磁场的影响。据推测，这种失败反映了这样一个事实，即恒星的形成和恒星的反馈，以及SMBH的形成、吸积和反馈，都是在极小的亚星系尺度上发生的，这使得模拟在以合理的精度对它们进行建模同时分辨星系更大尺度的环境方面面临着巨大的挑战。在我们小组以前工作(Beckmann，Devriendt，Slyz 2018，Beckmann，Slyz&Devriendt 2019，Martin-Alvarez等2018，Katz，Martin-Alvarez等2019，Martin-Alvarez等2020)的基础上，DPhil项目的目标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，从重温经典的Bondi-Hoyle-Lyttleton吸积模型到点源上将其磁化，将黑洞放在一个孤立的银盘中，添加活动星系核反馈，最后转移到宇宙学环境。学生还将基于这些星系和宇宙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千米阵列仪器及其前体产生真实的模拟观测数据(与以贾维斯教授为中心的牛津大学射电天文观测小组合作)。

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).