Time：16:00-17:30, Tuesday, June 9 2026
Venue：E14-215
Host：Hongguang Liu,ITS
Speaker：Zhenhong Xiao, Fudan University
Title：Probing Regular Black Holes without Cauchy Horizons through Gravitational Lensing
Abstract：We examine the gravitational lensing signatures of Hayward-like regular black holes and Bardeen-like black holes and their potential observational distinction from a Schwarzschild black hole. In the weak-field limit, the deflection angle includes a small positive correction proportional to mℓ^2/b^3, indicating slightly stronger light bending than in Schwarzschild, though the effect remains observationally negligible at large impact parameters. Current galaxy-scale Einstein-ring data, such as from ESO325-G004, cannot yet constrain the regular-core scale ℓ. In the strong-deflection regime, for Sgr A* and M87*, the asymptotic position θ∞ is identical to Schwarzschild's. Nevertheless, ℓ modifies strong-lensing coefficients a¯,b¯, influencing angular separations s, relative flux ratio rmag, and time delays ΔT2,1. Our predicted values for these observables remain consistent with current data, suggesting that future high-precision measurements of strong-field lensing may distinguish Hayward-like/Bardeen-like from Schwarzschild black holes.
