Roche limit and stellar disruption in the Simpson--Visser spacetime

TL;DR

This study investigates how the Simpson--Visser black bounce spacetime influences tidal forces and Roche limits for various stars, affecting their potential disruption and observability near black holes like M87* and Sgr A*.

Contribution

It analyzes the impact of Simpson--Visser regularization on tidal disruption processes and introduces the Affine Model for realistic stellar deformation in this spacetime.

Findings

Differences in tidal forces depend on observer type (static vs. infalling).

The Roche radius varies with the regularized geometry and stellar type.

Disruption processes may occur inside or outside the event horizon, affecting observability.

Abstract

Due to the tidal forces that a black hole can produce, certain types of compact objects may undergo disruption as they approach the black hole. This disruption point is known as the Roche limit (or Roche radius). In this work, we studied the tidal forces arising from the presence of the Simpson--Visser black bounce. We analyzed the tidal forces both for a static observer and for a radially infalling observer and showed that differences arise depending on the choice of observer. We used the tidal forces together with the stellar binding forces to determine the Roche radius for neutron stars, white dwarfs, and Sun-like stars, and to investigate how the Simpson--Visser regularization affects the tidal disruption of these astrophysical objects. We also examined whether, for astrophysical black holes such as M87* and Sgr~A*, these stellar disruption processes occur inside or outside the event horizon, and thus whether they are observable. To provide a more realistic dynamical description, we implement the Affine Model to evaluate the tidal deformation of neutron stars, white dwarfs, and main-sequence stars, assessing how the regularized geometry and the black hole mass govern the evolution of the stellar axes.