标题： 黑洞周围的磁化等离子体阴影：轴子等离子云 显示英文标题

标题： Shadow of black hole surrounded by magnetized plasma: Axion-plasmon cloud

摘要： 通过利用黑洞（BH）的极端环境作为轴子-光子相互作用的潜在场所，我们使用一种产生轴子的磁化等离子体模型来研究渐近平坦旋转黑洞浸入轴子-等离子体云时的阴影。 为了揭示轴子在黑洞黑暗阴影中的足迹，本文探讨了固定轴子-等离子体背景对围绕旋转黑洞的入射光子运动的影响。 在某些自由参数设定下，我们发现围绕旋转黑洞的轴子-等离子体云会影响阴影的形状和大小，其作用方式使其与非磁化等离子体和标准真空解区分开来。 通过对高自旋黑洞的限制，我们表明随着轴子-等离子体耦合强度的增加，黑洞阴影的大小也会增大。 有趣的是，我们的分析表明，随着轴子质量变重，它会在阴影上留下微妙的印记。 相反，在非旋转极限（Schwarzschild）情况下，通过恢复黑洞阴影形状的球对称性，其大小会减小。 与阴影大小变化趋势一致，对周围有磁化等离子体包围的黑洞能量发射的研究表明，存在轴子-等离子体云的情况下，旋转黑洞的最大能量发射率比非磁化等离子体和真空解的情况有所增加。 随后，通过放松旋转条件，轴子-等离子体云会导致黑洞的能量发射率下降。 显示英文摘要

摘要： By exploiting the extreme environment of the black hole (BH) as a potential place for axion-photon interaction, we use an axion-producing model of the magnetized plasma to study the shadow of an asymptotically flat rotating BH immersed into an axion-plasmon cloud. By aiming to reveal footprints of axion in the dark shadow of BH, we in this paper explore the influence of the fixed axion-plasmon background on the motion of incident photons around the rotating BH. Under some free parameter settings, we find that axion-plasmon cloud around rotating BH affects the shape and size of the shadow in such a way that its role is distinguishable from non-magnetized plasma and standard vacuum solutions. By being limited to high rotation BH, we show that the size of the BH shadow increases as the axion-plasmon coupling gets strong. Interestingly, our analysis indicates that as the mass of axion gets heavier, it can leave a subtle imprint of itself on the shadow. Conversely, in the non-rotating limit (Schwarzschild), by recovering the spherical symmetry of the shadow shape of BH, its size decreases. In coordination with the trend of change in shadow size, the investigation of the energy emission from the BH surrounded by the magnetized plasma shows that the maximal energy emission rate from the rotating BH in the presence of axion-plasmon cloud increases compared to the non-magnetized plasma and the vacuum solutions. Subsequently, by relaxing the rotation, the axion-plasmon cloud causes a decrease in the energy emission rate from the BH.