First M87 Event Horizon Telescope Results. VIII. Magnetic Field Structure near The Event Horizon
First M87 Event Horizon Telescope Results. VIII. Magnetic Field Structure near The Event Horizon
复制标题
第一个 M87 事件视界望远镜结果。
DOI：
10.3847/2041-8213/abe4de
复制
发表时间：
2021-03
影响因子：
7.9
通讯作者：
Bouman
中科院分区：
文献类型：
--
作者：
Akiyama Kazunori;Algaba Juan Carlos;Alberdi Antxon;Alef Walter;Anantua Richard;Asada Keiichi;Azulay Rebecca;Baczko Anne-Kathrin;Ball David;Balokovic Mislav;Barrett John;Benson Bradford A.;Bintley Dan;Blackburn Lindy;Blundell Raymond;Bol;Wilfred;Bouman
事件视界望远镜（EHT）在230 GHz的观测现在已经在事件视界尺度上成像了M87超大质量黑洞周围的偏振辐射。这种偏振同步辐射探测了黑洞附近的磁场结构和等离子体特性。在这里，我们比较了解决的极化结构观察到的EHT，沿着与同时未解决的意见与阿塔卡马大型毫米/亚毫米阵列，从理论模型的预期。低分数的线性偏振在解决的图像表明，偏振被打乱的尺度小于EHT光束，我们归因于法拉第旋转内部的发射区域。在一个简单的单区发射模型中，我们估计了辐射等离子体的平均密度n_e为10^4-7 cm-3量级，磁场强度B为1-30 G量级，电子温度Te为（1-12）× 10^10 K量级。我们表明，净方位线极化图案可能会导致有组织的，极向磁场的发射区。在定量比较与一个大型库的模拟极化图像从广义相对论磁流体动力学（GRMHD）模拟，我们确定了一个子集的物理模型，可以解释的极化EHT观测的关键功能，同时产生足够的功率相对论射流。一致的GRMHD模型都是磁吸积盘，其中近视界磁场在动力学上是重要的。我们利用这些模型推断出M87黑洞的质量吸积速率为（3-20）× 10^-4 Msun yr-1。
Event Horizon Telescope (EHT) observations at 230 GHz have now imaged polarized emission around the supermassive black hole in M87 on event-horizon scales. This polarized synchrotron radiation probes the structure of magnetic fields and the plasma properties near the black hole. Here we compare the resolved polarization structure observed by the EHT, along with simultaneous unresolved observations with the Atacama Large Millimeter/submillimeter Array, to expectations from theoretical models. The low fractional linear polarization in the resolved image suggests that the polarization is scrambled on scales smaller than the EHT beam, which we attribute to Faraday rotation internal to the emission region. We estimate the average density n_e of order 10^4-7 cm-3, magnetic field strength B of order 1-30 G, and electron temperature Te of order (1-12) x 10^10 K of the radiating plasma in a simple one-zone emission model. We show that the net azimuthal linear polarization pattern may result from organized, poloidal magnetic fields in the emission region. In a quantitative comparison with a large library of simulated polarimetric images from general relativistic magnetohydrodynamic (GRMHD) simulations, we identify a subset of physical models that can explain critical features of the polarimetric EHT observations while producing a relativistic jet of sufficient power. The consistent GRMHD models are all of magnetically arrested accretion disks, where near-horizon magnetic fields are dynamically important. We use the models to infer a mass accretion rate onto the black hole in M87 of (3-20) x 10^-4 Msun yr-1.