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arXiv 2104.11301astro-ph.HE
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黑洞磁场及其在圆极化图像上的印记

Black Hole Magnetic Fields and Their Imprint on Circular Polarization Images

Angelo Ricarte, Richard Qiu, Ramesh Narayan

摘要:

黑洞吸积流的圆极化可以编码底层磁场结构的性质。利用广义相对论磁流体动力学(GRMHD)模拟,我们研究了磁场几何形状对事件视界望远镜(EHT)可能观测到的圆偏振图像的影响。我们将图像分解成在这些模型中产生圆偏振的不同机制,这些机制对视线方向和磁场的扭曲都很敏感。在这些模型中,随着时间的推移,一个稳定的符号的圆偏振,观察到的几个来源,可以归因于这些属性的稳定性。我们说明了如何不同方面的一个通用的螺旋磁场几何形状成为印在圆偏振图像。我们还确定了新的影响光弯曲的圆偏振图像上的事件视界尺度。结果之一是在正面系统中连续光子环的符号翻转,如果可以观察到并且没有被法拉第旋转破坏,可以直接编码接近的磁场的旋向。

英文摘要:

The circular polarization of black hole accretion flows can encode properties of the underlying magnetic field structure. Using general relativistic magnetohydrodynamics (GRMHD) simulations, we study the imprint of magnetic field geometry on circular polarization images potentially observable by the Event Horizon Telescope (EHT). We decompose images into the different mechanisms that generate circular polarization in these models, which are sensitive to both the line of sight direction and twist of the magnetic field. In these models, a stable sign of the circular polarization over time, as observed for several sources, can be attributed to a stability of these properties. We illustrate how different aspects of a generic helical magnetic field geometry become imprinted on a circular polarization image. We also identify novel effects of light bending that affect the circular polarization image on event horizon scales. One consequence is the sign flipping of successive photon rings in face-on systems, which if observable and uncorrupted by Faraday rotation, can directly encode the handedness of the approaching magnetic field.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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