1. Tides and traversability in gravastars and other related geometries
- Author
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Tomasini, Cecilia, Simeone, Claudio, and de Celis, Emilio Rubín
- Subjects
General Relativity and Quantum Cosmology - Abstract
Tidal effects related to the traversability across thin shells are examined in spherically symmetric geometries. We focus mainly on shells separating inner from outer regions of gravastars (de Sitter -- i.e., $\Lambda>0$ -- interior and Schwarzschild exterior of mass parameter $M$), but we also examine other related geometries by including the possibility of a negative cosmological constant and, besides, non trivial topologies where the shell separates two outer regions. The analysis is developed for radially traversing objects and for tides in both radial and transverse directions, which present difficulties of somewhat different nature. Transverse tides are unavoidable across shells which satisfy the flare-out condition, while shells in trivial topologies, i.e. geometries with one asymptotic region, are more indulgent with the issue of insurmountable tides. Besides, contradicting other cases analyzed in previous works, we find that large radial tides cannot be avoided when traveling across the shell in the gravastar solution, but in non-trivial topologies they can. We study with special attention the traversability in practice of the transition layer in the thin-shell gravastar solution. In particular, a finite object which traverses radially the shell in a gravastar with $\sqrt{\Lambda}\ll 1/M$ undergoes a compression effect in both the transverse and the radial directions due to the tides associated to the thin layer. The results are interpreted in terms of the total momentum transfer obtained by integrating the travel time of the object., Comment: 14 pages, no figures
- Published
- 2024