高能天体物理研究组知识库

We study analytically the shadow cast by the rotating black hole in the perfect fluid dark matter. The apparent shape of the shadow depends upon the black hole spin a and the perfect fluid dark matter intensity parameter k (k > 0). In general, the shadow is a perfect circle in the non-rotating case (a = 0) and a deformed one in the rotating case (a not equal 0). The deformation gets more and more significant with the increasing a, similar to the Schwarzschild and Kerr black holes. In addition, there exists a reflection point (k) over tilde (0). When k < <(k)over tilde>(0), the size of the shadow decreases with the increasing k and the distortion increases with the increasing k. When k > 0, (k) over tilde (0), the size of the shadow increases with the increasing k and the distortion decreases with the increasing k. Furthermore, the energy emission rate of the black hole in the perfect fluid dark matter increases with the increasing k and the peak of the emission shifts to higher frequencies. Finally, we propose that to observe the effect of the black hole spin a and the perfect fluid dark matter intensity k on the shadow of the black hole Sgr A* at the center of the Milky Way, highly improved techniques would be necessary for the development of future astronomical instruments.