Black hole evolution in the Bondi–Hoyle–Lyttleton accretion model.

In this paper, we exhibit analytical solutions for the evolution of the mass of an astrophysical object accreting cosmic fluid according to the Bondi–Hoyle–Lyttleton mechanism. The key assumption of this model is that the adiabatic speed of sound within the accreted fluid directly affects the rate of change of the mass of the accreting object. We consider different literature equations of state, as the (Modified) Berthelot, Logotropic, generalized polytropic of index n, and quadratic models. We assume the fluid to evolve either according to General Relativity or to the Randall-Sundrum type 1 gravity model far away from the astrophysical object in an asymptotically Friedman universe. We claim that this accretion mechanism is unlikely to affect the mass-radius relationship of the photon sphere beyond the Schwarzschild one at the present time, and that the critical point of accretion in the (Modified) Berthelot fluid flow is hidden by the event horizon. Our work belongs to the broader research line investigating the interplay of small-scale and large-scale Physics in the modeling of gravitational phenomena. [ABSTRACT FROM AUTHOR]