Wave and particle probes of a regular T-duality-inspired black hole with gravitational self-energy

Abstract

Recently it was shown that a non-local T-duality-inspired smearing of the point mass introduces a finite zero-point length, while the regularized Newtonian gravitational self-energy is promoted to an additional source for the spacetime. The result is a nonsingular black-hole geometry whose ADM mass contains a finite self-energy contribution and whose extremal Planck-scale remnant sector has been proposed as a possible dark-matter component. We study how this spacetime would affect two familiar physical signals: the ringing of a massive scalar field and the motion of particles and light near the horizon. The zero-point length smooths the central region and changes the strong-field potential outside the horizon. On the wave side, we find that making the scalar field heavier increases the oscillation frequency and makes the damping weaker, a behavior associated with long-lived ringing. On the particle side, increasing the zero-point length makes the photon orbit and the innermost stable circular orbit more compact in physical mass units. The corresponding shadow becomes smaller, the photon-ring frequency becomes larger, and the orbital binding energy increases. These results show that the same regularizing correction leaves related imprints in wave propagation, black-hole shadows and circular-orbit physics.