https://doi.org/10.1140/epjc/s10052-025-15063-3
Regular Article - Theoretical Physics
Scalarizations of qOS-extremal black hole and Aretakis instability
Center for Quantum Spacetime, Sogang University, 04107, Seoul, Republic of Korea
a
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Received:
1
October
2025
Accepted:
10
November
2025
Published online:
18
November
2025
Abstract
We study scalarization of quantum Oppenheimer–Snyder (qOS)-extremal black hole in the Einstein–Gauss–Bonnet-scalar theory. This black hole is described by mass (
) with 
quantum parameter. Investigating the onset of scalarization, we find the appearance of the single branch of scalarized qOS-extremal black holes. To obtain the tachyonic scalar cloud being a seed to generate the single branch of scalarized qOS-extremal black holes, we consider the near-horizon geometry of the Bertotti–Bobinson (BR) spacetime. In this case, it is shown that the appearance of a large scalar cloud at the horizon (
) is a new feature to represent onset scalarization of extremal black holes for tachyon with negative mass. However, it is not related to the Aretakis instability of a propagating scalar with standard mass around the BR spacetime, showing polynomial instability of the ingoing time v. The Aretakis instability is connected to the scalar cloud with standard mass, indicating the blow-up at the horizon.
© The Author(s) 2025
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