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arXiv 2602.20893astro-ph.HEastro-ph.CO
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磁约束吸积盘模拟中的磁填充及其对M87喷流的影响

The magnetic filling in magnetically arrested accretion disk simulations and its impact on the jet in M87

University of Würzburg(维尔茨堡大学);Goethe Universität Frankfurt(法兰克福歌德大学);Shanghai Jiao Tong University(上海交通大学)

Felix Glaser, Christian M. Fromm, Yosuke Mizuno, Matthias Kadler, Karl Mannheim

AI总结:

研究磁填充对M87喷流的影响,通过GRMHD模拟探讨磁能分布与喷流特性,发现高磁填充增强电磁能量和角动量传输,提高极化率,支持低亮度AGN模型。

摘要:

磁约束吸积盘(MAD)在黑洞喷流模拟中成功建模低亮度活动星系核如M87*。Fishbone-Moncrief环被广泛用于此目的。我们研究了环内磁矢量势的范围,即磁填充因子,其在MAD模拟中尚未被研究。我们使用五组三维广义相对论磁流体力学(GRMHD)模拟,初始时大规模环体浸没在弱的环向磁场中。为了研究初始磁场空间范围的影响,即环中的磁能含量,我们将其按磁填充因子与环向几何面积的比例进行缩放。常见的填充因子选择被补充并研究,以考虑改变的能耗和角动量传输。进一步,我们研究了同步辐射在M87上86 GHz的极化辐射印记,与VLBI观测进行比较。我们的模拟显示,提高的填充因子显著增加喷流中的电磁能量贡献和向外角动量传输,由于环中初始磁能含量的增加。高磁填充显示出增加的线性极化率,与M87*观测到的15%一致。我们发现喷流形态更倾向于由MAD事件产生的盘垂直磁通管。我们显示,GRMHD模拟在M87*喷流基底处括定了喷流宽度测量。环中磁填充的增加产生比参考模型更明亮的喷流,因此我们发现高填充适合其他低亮度AGN的扩展GRMHD喷流模型。

英文摘要:

Magnetically arrested accretion disks (MADs) in black hole jet launching simulations are very successful in modelling low-luminosity active galactic nuclei (AGN) like M87*. The Fishbone-Moncrief torus is well established for this purpose in numerical astrophysics. The extent of the magnetic vector potential inside the torus that we coin the filling factor has not been studied before in the case of MAD simulations. We employ five 3D general relativistic magneto-hydrodynamics (GRMHD) simulations initialized with large-scale tori, that are immersed in weak, poloidal magnetic fields. To study the impact of the spatial extent of the initial magnetic field, hence the magnetic energy content in the torus, we scale it with the filling factor w.r.t. the poloidal geometric area of the mass density distribution. A common choice of the filling factor is complimented and investigated in terms of altered energetics and angular momentum transport. Further, we investigate the polarized, radiative imprints of synchrotron emission on M87 at 86 GHz, comparing them with VLBI observations. Our simulations show that elevated filling factors significantly increase the electromagnetic energy contributions and outward angular momentum transport in the jet, due to the initially increased magnetic energy-content in the torus. High magnetic fillings exhibit increased linear polarization fractions, agreeing with the observed 15$\%$ in M87*. We find the jet morphology more prone to disk-vertical flux tubes generated by MAD events. We show, that GRMHD simulations bracket the jet width measurements at the jet base in M87*. Increased magnetic filling of the torus produces jets that are noticeably brighter downstream compared to our reference models, hence, we find high fillings well suited for extended GRMHD jet models of other low-luminosity AGN, as well.

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