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

TL;DR

This paper studies how tidal forces and stellar disruptions behave in a charged black hole model influenced by nonlinear electrodynamics and Lorentz symmetry violation, revealing effects on tidal forces and disruption radii.

Contribution

It introduces the Kalb-Ramond-ModMax black hole solution and analyzes the impact of parameters on tidal forces, disruption radii, and stability, highlighting new effects of nonlinearity and Lorentz violation.

Findings

Radial tidal force sign inversion between horizons

Tidal forces diverge in the phantom sector, indicating instability

Parameter l shifts the relation between horizon and disruption radius

Abstract

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 $\gamma$ and Lorentz symmetry violation by the parameter $l$. In the canonical sector ($\alpha=1$), 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 $\gamma$ regulates the nonlinear electromagnetic contribution. The angular tidal force is predominantly compressive, $l$ shaping the effective geometry, and $\gamma$ acting as a damping factor. In the phantom sector ($\alpha=-1$), tidal forces and geodesic deviation diverge, indicating a tidal instability, with $l$ and $\gamma$ 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 $\gamma$ 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.