First Sagittarius A* Event Horizon Telescope Results. V. Testing Astrophysical Models of the Galactic Center Black Hole
First Sagittarius A* Event Horizon Telescope Results. V. Testing Astrophysical Models of the Galactic Center Black Hole
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DOI：
10.3847/2041-8213/ac6672
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发表时间：
2022-05
期刊：
影响因子：
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通讯作者：
K. Akiyama;A. Alberdi;W. Alef;Juan Carlos Algaba;R. Anantua;K. Asada;R. Azulay;U. Bach;
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文献类型：
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作者：
K. Akiyama;A. Alberdi;W. Alef;Juan Carlos Algaba;R. Anantua;K. Asada;R. Azulay;U. Bach;
在这篇文章中，我们首次对事件视界望远镜(EHT)2017年对SgrA*的观测进行了物理解释。我们的主要方法是将230 GHz已分辨的EHT数据和从射电到X射线波长的未分辨非EHT观测数据与基于时间相关的一般相对论磁流体动力学模拟的模型库中的预测进行比较，其中包括排列、倾斜和恒星风馈送的模拟；辐射传递假设热电子分布函数和非热电子分布函数。我们根据EHT230 GHz数据和在86 GHz、2.2μm和X射线的观测数据得出的11个约束对模型进行了测试。所有模型都至少有一个约束不合格。光曲线变化性提供了一个特别严重的限制，几乎所有的强磁化(磁阻止盘(MAD))模型和很大一部分弱磁化模型都失败了。许多模型只不符合可变性约束。我们确定了这些模型中的一个很有希望的簇，它们是MAD的，倾角在≤30°。它们的吸积率(5.2~9.5)×10−9M⊙yr−1，测辐射光度(6.8~9.2)×10 35erg S−1，流出功率(1.3~4.8)×10 38erg S−1。我们还发现，所有I≥为70°的模型和所有离子和电子温度相等的模型一样，至少有两个约束失效；探索性的非热模型集倾向于具有更高的2.2μm通量密度；冷电子的数量由于韧致辐射过剩的风险而受到X射线约束的限制。最后，我们讨论了模型的物理和数值限制，强调了动力学效应和模拟持续时间的可能重要性。
In this paper we provide a first physical interpretation for the Event Horizon Telescope's (EHT) 2017 observations of Sgr A*. Our main approach is to compare resolved EHT data at 230 GHz and unresolved non-EHT observations from radio to X-ray wavelengths to predictions from a library of models based on time-dependent general relativistic magnetohydrodynamics simulations, including aligned, tilted, and stellar-wind-fed simulations; radiative transfer is performed assuming both thermal and nonthermal electron distribution functions. We test the models against 11 constraints drawn from EHT 230 GHz data and observations at 86 GHz, 2.2 μm, and in the X-ray. All models fail at least one constraint. Light-curve variability provides a particularly severe constraint, failing nearly all strongly magnetized (magnetically arrested disk (MAD)) models and a large fraction of weakly magnetized models. A number of models fail only the variability constraints. We identify a promising cluster of these models, which are MAD and have inclination i ≤ 30°. They have accretion rate (5.2–9.5) × 10−9 M ⊙ yr−1, bolometric luminosity (6.8–9.2) × 1035 erg s−1, and outflow power (1.3–4.8) × 1038 erg s−1. We also find that all models with i ≥ 70° fail at least two constraints, as do all models with equal ion and electron temperature; exploratory, nonthermal model sets tend to have higher 2.2 μm flux density; and the population of cold electrons is limited by X-ray constraints due to the risk of bremsstrahlung overproduction. Finally, we discuss physical and numerical limitations of the models, highlighting the possible importance of kinetic effects and duration of the simulations.