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Light rings and causality for nonsingular ultracompact objects sourced by nonlinear electrodynamics

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arxiv 2406.07957 v3 pith:CPCO2VLC submitted 2024-06-12 gr-qc hep-th

Light rings and causality for nonsingular ultracompact objects sourced by nonlinear electrodynamics

classification gr-qc hep-th
keywords electrodynamicslightnonlinearnonsingularultracompactobjectsringssourced
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved
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We study observational signatures of nonsingular ultracompact objects regularized by nonlinear electrodynamics. The phenomenon of birefringence causes photons of different polarizations to propagate with respect to two distinct metrics, which manifests itself in the appearance of additional light rings surrounding the ultracompact object. We analyze the observational consequences of this result and illustrate our findings based on three regular black hole models commonly considered in the literature. We find that nonsingular horizonless ultracompact objects sourced by nonlinear electrodynamics possess an odd number of light rings and discuss the viability of this model as an effective description of their properties. In addition, we compare the phase velocities of polarized light rays propagating in nonsingular geometries sourced by nonlinear electrodynamics to the corresponding phase velocity in the Schwarzschild spacetime and demonstrate that regularizing the singularity by means of a theory that does not adhere to the Maxwell weak-field limit may lead to the emergence of acausal regions.

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Cited by 6 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

  1. Exact Relevant Stress-Tensor Flows and a Causality No-Go in Self-Dual Electrodynamics

    hep-th 2026-06 unverdicted novelty 7.0

    Exact power-law family of duality-preserving nonlinear electrodynamics constructed via stress-tensor flows, with a causality no-go result showing only the undeformed Maxwell seed is causal in the relevant regime.

  2. Photon Propagation and Black Hole Imaging in Kruglov Nonlinear Electrodynamics

    gr-qc 2026-04 unverdicted novelty 5.0

    In Kruglov's Born-Infeld-type nonlinear electrodynamics, the effective photon geometry around a charged black hole produces q-dependent shifts in light deflection, shadow radius, and accretion disk images, including s...

  3. Photon Propagation and Black Hole Imaging in Kruglov Nonlinear Electrodynamics

    gr-qc 2026-04 unverdicted novelty 5.0

    In Kruglov nonlinear electrodynamics, small positive values of the parameter q produce stable photon orbits outside the event horizon and modify black hole shadows and relativistic images even when the spacetime metri...

  4. Properties of black holes in non-linear electrodynamics

    hep-th 2026-04 unverdicted novelty 5.0

    Analytic charged black holes in nonlinear electrodynamics with non-monotonic lapse functions support stable light rings and additional longer-lived quasinormal modes compared to Einstein gravity.

  5. Photon Propagation and Black Hole Imaging in Kruglov Nonlinear Electrodynamics

    gr-qc 2026-04 unverdicted novelty 4.0

    In Kruglov NED, small positive q can create stable photon orbits and reshape black-hole shadows and accretion images even when the metric stays close to Reissner–Nordström.

  6. Properties of black holes in non-linear electrodynamics

    hep-th 2026-04 unverdicted novelty 4.0

    Nonlinear electrodynamics black holes with non-monotonic lapse functions admit stable light rings and trapped near-horizon photon orbits that generate additional longer-lived quasinormal mode branches.