512 research outputs found
Black objects in the Einstein-Gauss-Bonnet theory with negative cosmological constant and the boundary counterterm method
We propose to compute the action and global charges of the asymptotically
anti-de Sitter solutions in Einstein-Gauss-Bonnet theory by adding boundary
counterterms to the gravitational action. The general expression of the
counterterms and the boundary stress tensor is presented for spacetimes of
dimension . We apply this tehnique for several different types of
black objects. Apart from static and rotating black holes, we consider also
Einstein-Gauss-Bonnet black string solutions with negative cosmological
constant.Comment: 27 pages, 6 figures, references added, discussion extende
magnetized static, balanced black holes with event horizon topology
We construct static, nonextremal black hole solutions of the Einstein-Maxwell
equations in spacetime dimensions, with an event horizon of topology. These configurations are asymptotically flat, the U(1) field
being purely magnetic, with a spherical distribution of monopole charges but no
net charge measured at infinity. They can be viewed as generalizations of the
static dipole black ring, sharing its basic properties, in particular the
presence of a conical singularity. The magnetized version of these solutions is
constructed by applying a Harrison transformation, which puts them into an
external magnetic field. For , balanced configurations approaching
asymptotically a Melvin universe background are found for a critical value of
the background magnetic field.Comment: 12 pages, 2 figure
Non-perturbative spinning black holes in dynamical Chern-Simons gravity
Spinning black holes in dynamical Einstein-Chern-Simons gravity are
constructed by directly solving the field equations, without resorting to any
perturbative expansion. This model is obtained by adding to the
Einstein-Hilbert action a particular higher-curvature correction: the
Pontryagin density, linearly coupled to a scalar field. The spinning black
holes are stationary, axi-symmetric, asymptotically flat generalisations of the
Kerr solution of Einstein's gravity, but they possess a non-trivial
(odd-parity) scalar field. They are regular on and outside the horizon and
satisfy a generalized Smarr relation. We discuss the deviations from Kerr at
the level of the spin and mass distribution, the horizon angular velocity, the
ergo-region and some basic properties of geodesic motion. For sufficiently
small values of the Chern-Simons coupling our results match those previously
obtained using a perturbative approach.Comment: 14 pages, 5 figure
- …