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gr-qc2025
Null fluid gravitational fields on Kerr manifolds and optical lifts of Sasaki structures
Masoud Ganji, Cristina Giannotti, Andrea Spiro
Building on the characterisation in [C. D. Hill, J. Lewandowski and P. Nurowski, Indiana Univ. Math. J. 57 (2008), 3131--3176] of 4-dimensional Lorentzian metrics adapted to an opt…
gr-qc2025
Black holes and black regions, horizons and barriers in Lorentzian manifolds
Cristina Giannotti, Andrea Spiro
We prove that if S is a time-oriented null hypersurface of a Lorentzian n-manifold (M, g), the causal world-lines, which intersect transversally S and are time-oriented in a compat…