Probing the Magnetic Field Structure in on Black Hole Horizon Scales with Polarized Radiative Transfer Simulations
Probing the Magnetic Field Structure in on Black Hole Horizon Scales with Polarized Radiative Transfer Simulations
复制标题
DOI：
10.3847/1538-4357/aa6193
复制
发表时间：
2016-01
期刊：
影响因子：
--
通讯作者：
R. Gold;J. McKinney;Michael D. Johnson;S. Doeleman
中科院分区：
文献类型：
--
作者：
R. Gold;J. McKinney;Michael D. Johnson;S. Doeleman
磁场被认为是驱动黑洞吸积系统中的吸积和相对论喷流，但控制这些现象的磁场结构仍然不确定。我们进行广义相对论（GR）偏振辐射传输的时间相关的三维GR磁流体动力学模拟模型的热同步辐射从银河系中心源人马座A*（Sgr A*）。我们将我们的结果与事件视界望远镜（EHT）的新偏振测量结果进行比较，并展示了在可见度（傅立叶）域中的偏振如何区分和约束具有不同磁场结构的吸积流模型。这些模型包括由磁旋转不稳定性驱动的磁盘中的小尺度场模型，以及磁制动磁盘中的大尺度有序场模型。我们还考虑了不同的电子温度和射流质量加载处方，控制磁盘，漏斗壁射流，和Blandford-Znajek驱动的漏斗射流的亮度。我们的模拟和观测之间的比较有利于模型与有序的磁场附近的黑洞事件视界在Sgr A*，虽然磁盘和喷流为主的发射可以令人满意地解释大多数当前的EHT数据。我们还讨论了如何黑洞阴影可以填充喷流发射或模仿的漏斗喷流发射的情况下。我们表明，更强的模型约束应该是可能的，即将到来的圆极化和更高的频率（349 GHz）的测量。
Magnetic fields are believed to drive accretion and relativistic jets in black hole accretion systems, but the magnetic field structure that controls these phenomena remains uncertain. We perform general relativistic (GR) polarized radiative transfer of time-dependent three-dimensional GR magnetohydrodynamical simulations to model thermal synchrotron emission from the Galactic Center source Sagittarius A* (Sgr A*). We compare our results to new polarimetry measurements by the Event Horizon Telescope (EHT) and show how polarization in the visibility (Fourier) domain distinguishes and constrains accretion flow models with different magnetic field structures. These include models with small-scale fields in disks driven by the magnetorotational instability as well as models with large-scale ordered fields in magnetically arrested disks. We also consider different electron temperature and jet mass-loading prescriptions that control the brightness of the disk, funnel-wall jet, and Blandford–Znajek-driven funnel jet. Our comparisons between the simulations and observations favor models with ordered magnetic fields near the black hole event horizon in Sgr A*, though both disk- and jet-dominated emission can satisfactorily explain most of the current EHT data. We also discuss how the black hole shadow can be filled-in by jet emission or mimicked by the absence of funnel jet emission. We show that stronger model constraints should be possible with upcoming circular polarization and higher frequency (349 GHz) measurements.