Null geodesics, causal structure, and matter accretion in Lorentzian-Euclidean black holes

Fuente: arXiv
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Main Authors: Capozziello, Salvatore, Battista, Emmanuele, De Bianchi, Silvia
Format: Preprint
Published: 2025
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author Capozziello, Salvatore
Battista, Emmanuele
De Bianchi, Silvia
author_facet Capozziello, Salvatore
Battista, Emmanuele
De Bianchi, Silvia
contents Recently, we introduced the Lorentzian-Euclidean black hole, a static and spherically symmetric solution of vacuum Einstein equations that exhibits a change in metric signature across the event horizon. In this framework, the analysis of radial trajectories of freely falling bodies proves that the central singularity can be avoided via a mechanism we interpret as atemporality, which is responsible for the shift of the time variable from real to imaginary values. In this paper, we further explore this model by first examining the behavior of null geodesics. Our investigation requires a set of signature-adaptive coordinate changes that generalize the local Lorentz transformations underlying General Relativity. We find that photon orbits, like their massive counterparts, cannot traverse the event horizon, thereby strengthening the previous result on the impossibility to reach the $r=0$ singularity. Additionally, we discuss the causal structure of the spacetime, provide the corresponding Penrose diagram, and analyze the process of matter accretion in the outer region of the black hole.
format Preprint
id arxiv_https___arxiv_org_abs_2507_08431
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Null geodesics, causal structure, and matter accretion in Lorentzian-Euclidean black holes
Capozziello, Salvatore
Battista, Emmanuele
De Bianchi, Silvia
General Relativity and Quantum Cosmology
High Energy Astrophysical Phenomena
High Energy Physics - Theory
Recently, we introduced the Lorentzian-Euclidean black hole, a static and spherically symmetric solution of vacuum Einstein equations that exhibits a change in metric signature across the event horizon. In this framework, the analysis of radial trajectories of freely falling bodies proves that the central singularity can be avoided via a mechanism we interpret as atemporality, which is responsible for the shift of the time variable from real to imaginary values. In this paper, we further explore this model by first examining the behavior of null geodesics. Our investigation requires a set of signature-adaptive coordinate changes that generalize the local Lorentz transformations underlying General Relativity. We find that photon orbits, like their massive counterparts, cannot traverse the event horizon, thereby strengthening the previous result on the impossibility to reach the $r=0$ singularity. Additionally, we discuss the causal structure of the spacetime, provide the corresponding Penrose diagram, and analyze the process of matter accretion in the outer region of the black hole.
title Null geodesics, causal structure, and matter accretion in Lorentzian-Euclidean black holes
topic General Relativity and Quantum Cosmology
High Energy Astrophysical Phenomena
High Energy Physics - Theory
url https://arxiv.org/abs/2507.08431