The capability of the Event Horizon Telescope (EHT) to image the nearest supermassive black hole candidates at horizon-scale resolutions offers a novel means to study gravity in its strongest regimes and to test different models for these objects. Here, we study the observational appearance at 230 GHz of a surfaceless black hole mimicker, namely a non-rotating boson star, in a scenario consistent with the properties of the accretion flow onto Sgr A*. To this end, we perform general relativistic magnetohydrodynamic simulations followed by general relativistic radiative transfer calculations in the boson star space-time. Synthetic reconstructed images considering realistic astronomical observing conditions show that, despite qualitative similarities, the differences in the appearance of a black hole -- either rotating or not -- and a boson star of the type considered here are large enough to be detectable. These differences arise from dynamical effects directly related to the absence of an event horizon, in particular, the accumulation of matter in the form of a small torus or a spheroidal cloud in the interior of the boson star, and the absence of an evacuated high-magnetization funnel in the polar regions. The mechanism behind these effects is general enough to apply to other horizonless and surfaceless black hole mimickers, strengthening confidence in the ability of the EHT to identify such objects via radio observations.

中文翻译：

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如何从黑洞中分辨出吸积的玻色子星

事件视界望远镜 (EHT) 在视界尺度分辨率下对最近的超大质量黑洞候选者进行成像的能力提供了一种新颖的方法来研究其最强区域的引力并测试这些物体的不同模型。在这里，我们在与人马座 A* 上的吸积流特性一致的情况下研究了无表面黑洞模拟物（即非旋转玻色子星）在 230 GHz 的观测外观。为此，我们执行一般相对论磁流体动力学模拟，然后在玻色子星时空进行一般相对论辐射传递计算。考虑到真实天文观测条件的合成重建图像表明，尽管存在质量相似性，黑洞（无论是否旋转）与此处考虑的这种类型的玻色子在外观上的差异大到可以被探测到。这些差异源于与缺乏事件视界直接相关的动力学效应，特别是物质在玻色星内部以小环面或球状云的形式积累，以及没有被疏散的高极区的磁化漏斗。这些效应背后的机制足以适用于其他无视界和无表面的黑洞模拟物，增强了人们对 EHT 通过无线电观测识别此类物体的能力的信心。物质在玻色星内部以小环面或球状云的形式积累，而极地地区没有抽真空的高磁化漏斗。这些效应背后的机制足以适用于其他无视界和无表面的黑洞模拟物，增强了人们对 EHT 通过无线电观测识别此类物体的能力的信心。物质在玻色星内部以小环面或球状云的形式积累，而极地地区没有抽真空的高磁化漏斗。这些效应背后的机制足以适用于其他无视界和无表面的黑洞模拟物，增强了人们对 EHT 通过无线电观测识别此类物体的能力的信心。