论文标题
旋转黑洞，没有$ \ mathbb {z} _2 $对称性及其阴影图像
Rotating black holes without $\mathbb{Z}_2$ symmetry and their shadow images
论文作者
论文摘要
最近检测到黑洞结合的重力波和黑洞阴影的第一张图像增强了测试强场政权中重力理论的可能性。在本文中，我们研究了一类类似Kerr的旋转黑洞的物理特性和阴影图像，它们的$ \ Mathbb {z} _2 $对称通常被打破。这种黑洞溶液可能在有效的低能量理论中出现，例如弦理论，例如弦理论。在理论不可屈服的框架内，我们要求类似Kerr的溶液在渐近上是平坦的，并假设保留了类似Carter的常数，从而使Geodesic方程完全可分开。在这两个要求的前提下，我们发现时空的$ \ mathbb {z} _2 $不对称的特征是两个任意函数的极角。阴影图像事实证明是$ \ mathbb {z} _2 $对称性的天体坐标。此外，阴影完全是任意功能之一的视而不见的。另一个功能虽然会影响阴影的明显大小，但它几乎不会扭曲阴影轮廓，并且与自旋参数没有堕落。因此，只有当黑洞与地球的质量和距离以非常精确测量时，该功能中的参数才能通过黑洞阴影来限制。
The recent detection of gravitational waves from black hole coalescences and the first image of the black hole shadow enhance the possibilities of testing gravitational theories in the strong-field regime. In this paper, we study the physical properties and the shadow image of a class of Kerr-like rotating black holes, whose $\mathbb{Z}_2$ symmetry is generically broken. Such black hole solutions could arise in effective low-energy theories of a fundamental quantum theory of gravity, such as string theory. Within a theory-agnostic framework, we require that the Kerr-like solutions are asymptotically flat, and assume that a Carter-like constant is preserved, enabling the geodesic equations to be fully separable. Subject to these two requirements, we find that the $\mathbb{Z}_2$ asymmetry of the spacetime is characterized by two arbitrary functions of polar angle. The shadow image turns out to be $\mathbb{Z}_2$ symmetric on the celestial coordinates. Furthermore, the shadow is completely blind to one of the arbitrary functions. The other function, although would affect the apparent size of the shadow, it hardly distorts the shadow contour and has merely no degeneracy with the spin parameter. Therefore, the parameters in this function can be constrained with black hole shadows, only when the mass and the distance of the black hole from the earth are measured with great precision.
