Regular black holes as an alternative to black bounce

The so-called black-bounce mechanism of singularity suppression, proposed by Simpson and Visser, consists of replacing the spherical radius r in the metric tensor with r2+a2, a=const>0. This removes a singularity at r=0 and its neighborhood from space-time and there emerges a regular minimum of the spherical radius that can be a wormhole throat or a regular bounce (if located inside a black hole). Instead, it is proposed here to make r=0 a regular center by proper (Bardeen type) replacements in the metric, preserving its form at large r. Such replacements are applied to a class of metrics satisfying the condition Rtt=Rrr for their Ricci tensor, in particular, to the Schwarzschild, Reissner-Nordström, and Einstein-Born-Infeld solutions. A simpler version of nonlinear electrodynamics (NED) is considered, for which a black hole solution is similar to the Einstein-Born-Infeld one but is simpler expressed analytically. All new regular metrics can be presented as solutions to NED-Einstein equations with radial magnetic fields. © 2024 American Physical Society.