Shadows of Kerr-like black holes in a modified gravity theory

In this paper, the shadows cast by non-rotating and rotating modified gravity black holes are investigated. In addition to the black hole spin parameter a and the inclination angle theta of observer, another parameter alpha measuring the deviation of gravitational constant from the Newton one is also found to affect the shape of the black hole shadow. The result shows that, for fixed values of a/M and theta, the size and perimeter of the shadows cast by the non-rotating and rotating black holes significantly increase with the parameter alpha, while the distortions decrease with alpha. Moreover, the energy emission rate of the black hole in high energy case is also investigated, and the result shows that the peak of the emission rate decreases with the parameter alpha.