Analogous Hawking Radiation from Astrophysical Black Hole Accretion

For the first time in literature, we provide an exact analytical scheme for calculating the analogous Hawking temperature and surface gravity for general relativistic accretion onto astrophysical black holes. Our calculation may bridge the gap between the theory of transonic astrophysical accretion and the theory of analogous Hawking radiation, and may allow one to compare the properties of the two types of horizons, electromagnetic and acoustic, in connection to the black hole physics. We show that the domination of the analogous Hawking radiation over the actual Hawking radiation may be a real astrophysical phenomena. We also discuss the possibilities of the emergence of analogous white holes around astrophysical black holes. Our calculation is general enough to accommodate accreting black holes with any mass.