1. Lower bound on the radii of light rings in traceless black-hole spacetimes.
- Author
-
Hod, Shahar
- Subjects
GEODESIC motion ,HYPERSURFACES - Abstract
Photonspheres, curved hypersurfaces on which massless particles can perform closed geodesic motions around highly compact objects, are an integral part of generic black-hole spacetimes. In the present compact paper we prove, using analytical techniques, that the innermost light rings of spherically symmetric hairy black-hole spacetimes whose external matter fields are characterized by a traceless energy-momentum tensor cannot be located arbitrarily close to the central black hole. In particular, we reveal the physically interesting fact that the non-linearly coupled Einstein-matter field equations set the lower bound r γ ≥ 6 5 r H on the radii of traceless black-hole photonspheres, where r
H is the radius of the outermost black-hole horizon. [ABSTRACT FROM AUTHOR]- Published
- 2023
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