3 research outputs found
Morris-Thorne wormholes with a cosmological constant
First, the ideas introduced in the wormhole research field since the work of
Morris and Thorne are briefly reviewed, namely, the issues of energy
conditions, wormhole construction, stability, time machines and astrophysical
signatures. Then, spherically symmetric and static traversable Morris-Thorne
wormholes in the presence of a generic cosmological constant are analyzed. A
matching of an interior solution to the unique exterior vacuum solution is done
using directly the Einstein equations. The structure as well as several
physical properties and characteristics of traversable wormholes due to the
effects of the cosmological term are studied. Interesting equations appear in
the process of matching. For instance, one finds that for asymptotically flat
and anti-de Sitter spacetimes the surface tangential pressure of the
thin-shell, at the boundary of the interior and exterior solutions, is always
strictly positive, whereas for de Sitter spacetime it can take either sign as
one could expect, being negative (tension) for relatively high cosmological
constant and high wormhole radius, positive for relatively high mass and small
wormhole radius, and zero in-between. Finally, some specific solutions with
generic cosmological constant, based on the Morris-Thorne solutions, are
provided.Comment: latex, 49 pages, 8 figures. Expanded version of the paper published
in Physical Review
Black Holes in Bulk Viscous Cosmology
We investigate the effects of the accretion of phantom energy with non-zero
bulk viscosity onto a Schwarzschild black hole and show that black holes
accreting viscous phantom energy will lose mass rapidly compared to the
non-viscous case. When matter is incorporated along with the phantom energy,
the black holes meet with the same fate as bulk viscous forces dominate matter
accretion. If the phantom energy has large bulk viscosity, then the mass of the
black hole will reduce faster than in the small viscosity case.Comment: 20 pages, 3 figures, accepted for publication in Int. J. Theor. Phy