Spherical Accretion in Alternative Theories of Gravity
Spherical Accretion in Alternative Theories of Gravity
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DOI：
10.3847/1538-4357/ac3a03
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发表时间：
2021-11
期刊：
影响因子：
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通讯作者：
A. Bauer;A. C'ardenas-Avendano;C. Gammie;N. Yunes
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文献类型：
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作者：
A. Bauer;A. C'ardenas-Avendano;C. Gammie;N. Yunes
M87星系中心黑洞的开创性图像引发了观测天文学和黑洞物理学交叉点的问题。黑洞阴影的半径能被测量到什么程度？这种测量能用来区分广义相对论和其他引力理论吗？我们探索这些问题，使用一个简单的球流模型在广义相对论，标量高斯-邦尼重力，Rezzolla和Zhidenko参数化度量。我们假设一个光学薄等离子体的幂律半径发射率。沿着的方式，我们提出了一个广义的邦迪流，以及一个分段的分析模型的亮度轮廓的冷流入。我们使用合成图像的二阶矩作为EHT观测量的代理，并计算二阶矩与黑洞阴影半径的比值。我们表明，修正广义相对论的这一比例的修正是subdominant相比，关键的影响参数的修正，我们认为，这是普遍正确的。在我们的简化模型的天体物理参数的不确定性占主导地位的重力理论参数的不确定性，强调的重要性，了解吸积模型，如果EHT是用来成功地测试重力理论。
The groundbreaking image of the black hole at the center of the M87 galaxy has raised questions at the intersection of observational astronomy and black hole physics. How well can the radius of a black hole shadow be measured, and can this measurement be used to distinguish general relativity from other theories of gravity? We explore these questions using a simple spherical flow model in general relativity, scalar Gauss–Bonnet gravity, and the Rezzolla and Zhidenko parameterized metric. We assume an optically thin plasma with power-law emissivity in radius. Along the way we present a generalized Bondi flow, as well as a piecewise analytic model for the brightness profile of a cold inflow. We use the second moment of a synthetic image as a proxy for EHT observables and compute the ratio of the second moment to the radius of the black hole shadow. We show that corrections to this ratio from modifications to general relativity are subdominant compared to corrections to the critical impact parameter, and we argue that this is generally true. In our simplified model the astrophysical parameter uncertainty dominates the gravity theory parameter uncertainty, underlining the importance of understanding the accretion model if EHT is to be used to successfully test theories of gravity.