论文标题
黑洞阴影的形状是否取决于观察者的运动状态？
Does the shape of the shadow of a black hole depend on motional status of an observer?
论文作者
论文摘要
在最近关于旋转黑洞阴影的工作[物理学。修订版D {\ bf 101}，084029（2020）]，我们提出了一种新的方法，以根据有限距离观察者的actrometical可观察者来计算阴影的大小和形状。在本文中，我们引入了阴影形状的失真参数，并讨论静态球形黑洞和Kerr黑洞的阴影的外观。我们表明，在任意观察者的角度看，球形黑洞的阴影的形状是圆形的，而在移动的观察者的角度来看，阴影的大小往往会缩小。阴影的直径甚至沿垂直于观察者运动的方向收缩。在特殊相对论中，这似乎不被理解为长度收缩效应。 Kerr黑洞的形状取决于观察者位于有限距离处的运动状态。尽管如此，发现没有一个周围的观察者可以将Kerr黑洞阴影的形状视为圆形。这些结果可能有助于在银河系中心观察射手座A*，因为我们的太阳系正在围绕中心黑洞移动。
In a recent work on rotating black hole shadows [Phys. Rev. D{\bf 101}, 084029 (2020)], we proposed a new approach for calculating size and shape of the shadows in terms of astrometrical observables with respect to finite-distance observers. In this paper, we introduce a distortion parameter for the shadow shapes and discuss the appearance of the shadows of static spherical black holes and Kerr black holes in a uniform framework. We show that the shape of the shadow of a spherical black hole is circular in the view of arbitrary observers, and the size of the shadows tends to be shrunk in the view of a moving observer. The diameter of the shadows is contracted even in the direction perpendicular to the observers' motion. This seems not to be understood as length contraction effect in special relativity. The shape of Kerr black holes is dependent on motional status of observers located at finite distance. In spite of this, it is found that there is not a surrounding observer who could view the shape of the Kerr black hole shadows as circularity. These results could be helpful for observation of the Sagittarius A* in the centre of the Milky Way, as our solar system is moving around the centre black hole.
