Paper detail

Tidal dynamics and stellar disruption in charged Kalb-Ramond black holes in nonlinear electrodynamics

We investigate tidal forces, geodesic deviation, and tidal disruption in the black hole spacetime described by the Kalb-Ramond-ModMax solution, where electromagnetic nonlinearity is governed by the parameter $γ$ and Lorentz symmetry violation by the parameter $l$. In the canonical sector ($α=1$), the radial tidal force exhibits a transition marked by a sign inversion between the horizons $r_{-}$ and $r_+$, signaling internal regimes of radial compression analogous to those of charged black holes; the parameter $l$ controls the strength and location of this transition, while $γ$ regulates the nonlinear electromagnetic contribution. The angular tidal force is predominantly compressive, $l$ shaping the effective geometry, and $γ$ acting as a damping factor. In the phantom sector ($α=-1$), tidal forces and geodesic deviation diverge, indicating a tidal instability, with $l$ and $γ$ affecting only the magnitude of the response. We further show that $l$ shifts the relation between the horizon radius $r_+$ and the tidal disruption radius $r_{\rm Roche}$, thereby modifying the critical (Hills) mass defined by $r_{\rm Roche}=r_+$. Tidal disruption of neutron stars occurs inside the horizon for supermassive black holes, whereas Sun-like stars are disrupted outside the horizon, with $γ$ becoming relevant only for ultramassive black holes with masses $\sim 10^{8}M_{\odot}$. Our results demonstrate that Kalb-Ramon-ModMax effects are largely suppressed for supermassive black holes, but may be relevant for intermediate-mass systems and observable tidal disruption events, offering an indirect probe of Lorentz violation and nonlinear electrodynamics in the strong-field regime.