[论文解读] Shadow signatures and energy accumulation in Lorentzian-Euclidean black holes

Emmanuele Battista, Salvatore Capozziello+1 more|arXiv (Cornell University)|Jan 15, 2026

Astrophysical Phenomena and Observations被引用 0

一句话总结

论文分析洛伦兹-欧几里得黑洞的阴影，揭示由于近光锥光传播导致的内阴影强度过剩，并将背反应与稳定光环进行比较。

ABSTRACT

The Lorentzian-Euclidean black hole has been recently introduced as a geodesically complete spacetime featuring a signature shift at the event horizon where causal geodesics are precluded from reaching the central $r=0$ singularity. In this paper, we investigate the shadows produced by this geometry to identify deviations from the standard Schwarzschild solution. Our analysis reveals an excess intensity in the inner shadow region that points to a potential observational signature of the novel behavior of light rays propagating near the event horizon. This excess could be a probe for horizon-scale modifications of black hole geometries. Furthermore, although the horizon surface of the Lorentzian-Euclidean black hole continuously accumulates photons and energy, we show that its backreaction response differs from that of stable light rings found in various exotic compact objects.

研究动机与目标

• Motivate the study of horizon-scale phenomenology in Lorentzian-Euclidean black holes.
• Characterize photon and light-ray dynamics near the horizon in this geometry.
• Identify observable shadow features that deviate from Schwarzschild predictions.
• Assess whether photon energy accumulation near the horizon induces backreaction
• Compare backreaction behavior with that of stable light rings in other compact objects.

提出的方法

• Describe the Lorentzian-Euclidean black hole metric and the signature change at r = 2M.
• Derive equatorial photon geodesics and the modified photon sphere condition.
• Perform ray-tracing with a thin accretion disk and GLM emission profile.
• Compute observed intensity using radiative transfer and redshift factors.
• Analyze inner-shadow region and quantify excess intensity near the horizon.
• Provide analytic approximation for the inner-shadow intensity (Eq. 21).

实验结果

研究问题

• RQ1 What observational signatures do shadows of Lorentzian-Euclidean black holes exhibit compared to Schwarzschild?
• RQ2 How does light behave near the horizon in the Lorentzian-Euclidean geometry and what is the nature of the inner shadow?
• RQ3 Does the accumulation of energy near the horizon lead to backreaction, and how does it differ from stable light rings?
• RQ4 Can the inner-shadow excess serve as a probe of horizon-scale modifications or quantum effects?

主要发现

• The photon sphere radius and the corresponding impact parameter are slightly smaller than in Schwarzschild due to the modified ε(r).
• Photon trajectories with b < b_c approach r = 2M but do not cross the horizon, circling it infinitely many times with infinite affine parameter.
• The shadow images are nearly Schwarzschild-like, but an inner-shadow region shows an excess intensity due to emissions near r = 2M.
• An analytic expression (Eq. 21) describes the inner-shadow excess, matching numerical results for small b/M.
• Backreaction from accumulated energy near the horizon causes the outer horizon surface to expand, contrasting with shrinking behavior of stable light rings in some horizonless models.