Gray-body factors for gravitational and electromagnetic perturbations around Gibbons–Maeda–Garfinkle–Horowitz–Strominger black holes
Abstract
While gray-body factors for a test scalar field in stringy black holes described by the renowned Gibbons–Maeda–Garfinkle–Horowitz–Strominger (GMGHS) solution have been analyzed in the literature, no such analysis exists for gravitons, likely due to the complexity of the perturbation equations. In this study, we utilize known data on quasinormal modes and the relationship between quasinormal modes and gray-body factors to derive these factors for gravitational and electromagnetic perturbations of the dilaton black hole. Our findings indicate that gray-body factors are significantly suppressed by the dilaton parameter as the black holes charge approaches its extreme value. The iso-spectrality between axial and polar channels of perturbations is broken in the presence of the dilaton field, which leads to different gray-body factors for different types of perturbations.