Regularity conditions for spherically symmetric solutions of Einstein-nonlinear electrodynamics equations; revised and improved version

TL;DR

This paper establishes regularity conditions at the center for static spherically symmetric solutions of Einstein equations coupled with nonlinear electrodynamics, providing explicit integral representations and analyzing various asymptotic behaviors.

Contribution

It introduces necessary and sufficient regularity conditions for NLE SSS solutions and presents a general linear integral representation involving key tensor invariants.

Findings

Regularity conditions at the center for NLE SSS solutions are derived.

Explicit integral representation of the metric in terms of electric field and invariants is provided.

Solutions can exhibit diverse asymptotic behaviors, including Reissner-Nordström and dS--AdS.

Abstract

In this report, the regularity conditions at the center for static spherically symmetric (SSS) solutions of the Einstein equations coupled to nonlinear electrodynamics (NLE) with Lagrangian $\mathcal{L}= \mathcal{L}(\mathcal{F})$, depending on the electromagnetic invariant $\mathcal{F}=F_{\mu\nu}\,F^{\mu\nu}/4$, are established. The traceless Ricci (TR) tensor eigenvalue $S$, the Weyl tensor eigenvalue $\Psi_2$ and the scalar curvature $R$ characterize the independent Riemman tensor invariants of SSS metrics. The necessary and sufficient regularity conditions for electric NLE SSS solutions require $\lim_{r\rightarrow 0}\{\Psi_2,S,R\}\rightarrow \{0,0,(0,4\Lambda+ 4\mathcal{L}(0))\}$, such that the metric function $Q(r)$ and the electric field $q_0F_{rt}=:\mathcal{E}$ behave as $\{Q,\dot Q,\ddot Q\}\rightarrow\{0,0,2\}$ and $\{\mathcal{E},\dot\mathcal{E},\ddot\mathcal{E}\}\rightarrow\{0,0,0\}$, as $r\rightarrow 0$. The general linear integral representation of the electric NLE SSS metric in terms of an arbitrary electric field $\mathcal{E}$, together with $\{\Psi_2,S,R\}$, is explicitly given. Moreover, beside the regular or singular behavior at the center, these solutions may exhibit different asymptotic behavior at spatial infinity such as the Reissner--Nordtr\"om (Maxwell) asymptotic, or present the dS--AdS or other kind of asymptotic.