Compact Objects in General Relativity and Beyond

Magnetized Dusty Black Holes and Wormholes

“…Thus, to match two q-Tolman solutions on a surface Σ (R = R * ), we must identify the values of F(R * ) and h(R * ) as well as the parameter q in these solutions. Then, by virtue of (19), these matching conditions are valid at all times at which both solutions remain regular. Furthermore, there is no necessity to adjust the choice of the radial coordinates on different sides of Σ because both quantities r and e −λ r are insensitive to reparametrizations of R, and the same is true for the functions h(R) and F(R) which behave as scalars at such reparametrizations.…”

“…The answer is that a maximum of r th is reached precisely at the horizon, a boundary between the R-and T-regions, and it is possible because h(R th ) = 1, so the reasoning used about the surface layer (see Equation ( 41)) does not work. In terms of the parametrization (19), we have a maximum of r th at η = π, when r ,α r ,α = 0.…”

“…A magnetized rotating wormhole was obtained in [18] as an exact solution to the Einstein equations. The recent papers [19,20] have presented specific examples of static traversable wormholes in Einstein-Dirac-Maxwell theory in four space-time dimensions, without explicit introduction of exotic matter, so that the Dirac fields themselves exhibit exotic properties [21]. Static, spherically symmetric wormhole solutions of asymptotically safe gravity have been recently studied in [22].…”

“…Rotational degrees of freedom are apparently able to replace exotic matter at wormhole construction. At least, some examples of rotating cylindrically symmetric wormhole models in GR have been built without NEC violation [43][44][45]; the recent examples with a static metric [19,20] contain a Dirac field involving spin; one can also mention exotic-free solutions in the Einstein-Cartan theory [46,47] containing nonzero torsion.…”