Hawking Radiation from Non-minimal Einstein--Yang--Mills Black Holes

Abstract

Abstract We study Hawking emission from the regular magnetic black hole of non-minimal Einstein--Yang--Mills theory. The geometry is supported by a Wu--Yang charge whose Yang--Mills field couples directly to curvature through the non-minimal susceptibility tensor. This coupling removes the central singularity. In the quasi-stationary approximation, where the temperature is fixed during the emission of individual quanta, we compute greybody factors for a real massless scalar, an electromagnetic field, and a neutral massless Dirac test field by direct integration of the corresponding one-dimensional scattering equations, compare them with the higher-order WKB approach, and integrate the resulting Hawking spectra. For a representative fixed charge, increasing the non-minimal coupling changes the greybody thresholds only moderately, while the Hawking temperature and particle luminosity are strongly suppressed close to extremality. A direct separation of temperature and greybody-factor effects shows that cooling supplies the largest number of suppressed orders of magnitude, although modified low-frequency transmission gives an additional reduction near the endpoint. The photon-plus-light-fermion luminosity falls by many orders of magnitude near the endpoint, and the residual massless flux becomes increasingly fermion dominated.