Bondi accretion disc luminosity around neutral and charged Simpson-Visser spacetimes

Abstract We investigate relativistic Bondi accretion in the Simpson-Visser spacetime, which, via a single parameter ℓ, interpolates between the Schwarzschild, regular black hole, extremal and wormhole regimes. First, we analyse the neutral Simpson-Visser geometry, recovering Schwarzschild at ℓ=0, and then its charged extension of the Reissner-Nordström metric. In both these cases, we derive the conservation equations and analyse two representative fluid models: a barotropic perfect fluid and a constituent with an exponential density profile. By varying the parameters across regimes, we locate critical (sonic) points and integrate velocity, density, and pressure profiles. Although near-horizon inflow velocities are similar across the different solutions, we find that the critical radius, as well as the resulting accretion rates and luminosities, change significantly depending on the value of the parameter and the type of fluid. Remarkably, the barotropic and exponential cases exhibit different trends in the outer regions. Moreover, by extending the analysis to the charged SV spacetime, we find that the presence of a central charge Q produces additional, albeit modest, shifts in the sonic radius which, in combination with those induced by the regularisation parameter ℓ, could provide a double observational marker. In particular, while ℓ acts predominantly on the position of the critical point, in the barotropic fluid case, the electromagnetic contribution of Q slightly dampens the inflow velocity near the horizon.