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

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arxiv 2507.08431 v1 pith:KYSV5IZH submitted 2025-07-11 gr-qc astro-ph.HEhep-th

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

classification gr-qc astro-ph.HEhep-th
keywords blackaccretioncausaleventgeodesicsholehorizonlorentzian-euclidean
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved
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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.

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