Accretion with shock cone morphology onto charged black holes in dilaton-massive gravity

Abstract

This study tested accretion onto a charged scalar black hole (BH) model within a massive-gravity framework. In this context, the analysis emphasizes the detailed dynamics of infalling matter, the determination of sonic points, and the response of different test fluids under varying conditions. The background spacetime is described by a charged dilatonic BH solution, and the conservation laws for particle flux and energy-momentum are explicitly formulated to allow treatment as a dynamical system. By recasting the accretion equations into an autonomous system, the critical conditions corresponding to sonic transitions are systematically identified and analyzed. Also, many fluid models are considered, including isothermal, barotropic, and polytropic fluids, covering regimes from ultra-stiff to sub-relativistic. Each fluid model produces distinct modifications to the Hamiltonian trajectories and radial velocity profiles, thereby influencing the overall accretion pattern. The parameters of massive gravity, particularly \(c_1\) and \(c_2\), shape the horizon structure, determine the positions of critical points, and potentially affect the formation and stability of accretion disks. The mass accretion rate, expressed in terms of metric function, fluid energy density, and radial inflow velocity, shows a decreasing trend with increasing \(c_1\) and \(c_2\), which implies a reduction in accretion efficiency. Additionally, the radiative properties of thin disks, including emitted flux, disk temperature, radiative efficiency, and luminosity, are suppressed for higher values of these parameters. In this case, the results illustrate that massive gravity not only modifies the behavior of matter inflow but also substantially diminishes the radiative output, offering potentially observable differences that can distinguish charged scalar BHs in massive gravity from their counterparts in standard general relativity (GR). We also numerically model matter accretion via the Bondi–Hoyle–Lyttleton (BHL) mechanism in the framework of massive gravity, showing that the modified shock cone structure, mass accretion rate, and the resulting QPOs are consistent with theoretical expectations, and highlighting their observability and differences from GR.