论文标题
关于黑洞成像的基本物理测试的注释：评论“在射手座的阴影中寻找额外的维度A $^*$”
Note on fundamental physics tests from black hole imaging: Comment on "Hunting for extra dimensions in the shadow of Sagittarius A$^*$"
论文作者
论文摘要
过去几年中的几项作品讨论了使用非常长的基线干涉量范围黑洞（BH）图像进行基本物理学的可能性，例如事件地平线范围望远镜（EHT）M87 $^*$和SAGITTARIUS A $^*$（使用SGR A $^*$）的M87 $^*$和SAGITTARIUS的图像，并使用size $ r _} BH阴影的$δ\ Mathcal {C} $。对于SGR A $^*$的EHT图像，$δ\ Mathcal {C} $上的限制由于2017年观察值的稀疏干涉覆盖范围，与M87 $^*$相比，SGR A $^*$的简短可变性时间表以及SGR的短变量时间表。关于这一点，我们对最近的预印本的结果发表评论，该结果据称使用SGR A $^*$的阴影的圆形性偏离了额外的尺寸的新限制。基于两个阴影的“相似性”，后者被引用为$ \ lyssim 10 \％$，而M87 $^*$，但是，这是一个不正确的假设，使后续结果无效。因此，在不久的将来，SGR A $^*$的图像的最简单测试将主要依靠$ r _ {\ rm sh} $，而其他可观察到的可观察结果，例如光子环和方位角角度失误，应很快可用并允许进行新颖的测试。
Several works over the past years have discussed the possibility of testing fundamental physics using Very Long Baseline Interferometry horizon-scale black hole (BH) images, such as the Event Horizon Telescope (EHT) images of M87$^*$ and Sagittarius A$^*$ (Sgr A$^*$), using the size $r_{\rm sh}$ and deviation from circularity $Δ\mathcal{C}$ of the BH shadow. For the case of the EHT image of Sgr A$^*$, limits on $Δ\mathcal{C}$ are not available due to the sparse interferometric coverage of the 2017 observations, alongside the short variability timescale of Sgr A$^*$ compared to M87$^*$. Concerning this point, we comment on the results of a recent preprint which purports to have derived new limits on extra dimensions using the deviation from circularity of Sgr A$^*$'s shadow. The latter is quoted to be $\lesssim 10\%$ as with M87$^*$, based on the "similarity" of the two shadows: however, this is an incorrect assumption, invalidating the subsequent results. In the immediate future, the simplest tests of fundamental physics from Sgr A$^*$'s image will therefore mostly have to rely on $r_{\rm sh}$, whereas additional observables such as the photon ring and azimuthal angle lapse should soon be available and allow for novel tests.
