论文标题

黑洞阴影的可见性低亮度AGN

Visibility of Black Hole Shadows in Low-luminosity AGN

论文作者

Bronzwaer, Thomas, Davelaar, Jordy, Younsi, Ziri, Mościbrodzka, Monika, Olivares, Héctor, Mizuno, Yosuke, Vos, Jesse, Falcke, Heino

论文摘要

积聚黑洞倾向于显示一个名为黑洞阴影的特征性深色中心区域,该区域仅取决于时空/观察者的几何形状,并传达有关黑洞质量和旋转的信息。相反,观察到的中央亮度抑郁或图像阴影还取决于发射区域的形态。在本文中,我们研究了在基于GRMHD的积聚黑洞模型中观察有意义的黑洞阴影的天体物理要求。特别是,我们确定了两个过程,图像阴影可以与黑洞阴影有所不同:疏散吸积流区域的疏散,可以使图像阴影更大,而不是黑洞阴影,而黑洞阴影则通过光学厚实的浓度较厚的积光流动,可以使图像阴影更小,而不是黑洞的阴影,而不是黑洞的阴影。我们在哪个模型中研究了模型的图像阴影与它们相应的黑洞阴影匹配,其中两者的模型彼此偏离。我们发现,鉴于一个紧凑而光学薄的发射区域,我们的模型可以将黑洞的阴影尺寸测量至5%的精度。我们表明,对于我们考虑的所有疯狂模拟以及一些理智的模拟,通常都满足了这些条件。

Accreting black holes tend to display a characteristic dark central region called the black-hole shadow, which depends only on spacetime/observer geometry and which conveys information about the black hole's mass and spin. Conversely, the observed central brightness depression, or image shadow, additionally depends on the morphology of the emission region. In this paper, we investigate the astrophysical requirements for observing a meaningful black-hole shadow in GRMHD-based models of accreting black holes. In particular, we identify two processes by which the image shadow can differ from the black-hole shadow: evacuation of the innermost region of the accretion flow, which can render the image shadow larger than the black-hole shadow, and obscuration of the black-hole shadow by optically thick regions of the accretion flow, which can render the image shadow smaller than the black-hole shadow, or eliminate it altogether. We investigate in which models the image shadows of our models match their corresponding black-hole shadows, and in which models the two deviate from each other. We find that, given a compact and optically thin emission region, our models allow for measurement of the black-hole shadow size to an accuracy of 5%. We show that these conditions are generally met for all MAD simulations we considered, as well as some of the SANE simulations.

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