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arXiv · 2403.15537

The cosmic trimmer: Black-hole hair in scalar-Gauss-Bonnet gravity is altered by cosmology

Eugeny Babichev·Ignacy Sawicki·Leonardo G. Trombetta
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Abstract

Static black holes in general relativity modified by a linear scalar coupling to the Gauss-Bonnet invariant always carry hair. We show that the same mechanism that creates the hair makes it incompatible with a cosmological horizon. Other scalar-tensor models do not have this problem when time dependence of the scalar provides a natural matching to cosmology. Scalar-Gauss-Bonnet gravity is particularly rigid, and such a scenario does not help. An extra operator makes the theory behave like the other models, and the cosmological horizon can be accommodated. The hair, however, is drastically altered.

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Eugeny Babichev, Ignacy Sawicki, Leonardo G. Trombetta. 2024-03-22. The cosmic trimmer: Black-hole hair in scalar-Gauss-Bonnet gravity is altered by cosmology. https://doi.org/10.1103/physrevd.111.l041502

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