Date
March 27 (Thu) at 15:00 - 16:30, 2025 (JST)
Speaker
  • Shinji Tsujikawa (Professor, Graduate School of Advanced Science and Engineering, Faculty of Science and Engineering, Waseda University)
Language
English
Host
Yuki Yokokura

We show that nonsingular black holes (BHs) realized in nonlinear electrodynamics are always prone to Laplacian instability around the center because of a negative squared sound speed in the angular direction. This is the case for both electric and magnetic BHs, where the instability of one of the vector-field perturbations leads to enhancing a dynamical gravitational perturbation in the even-parity sector. Thus, the background regular metric is no longer maintained in a steady state. We also generalize our analysis to the case in which a scalar field is present besides the U(1) gauge field and find no explicit examples of linearly stable nonsingular BHs. Our results suggest that the construction of regular BHs without instabilities is generally challenging within the scheme of classical field theories.

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