8 research outputs found
Higher Dimensional Taub-NUTs and Taub-Bolts in Einstein-Maxwell Gravity
We present a class of higher dimensional solutions to Einstein-Maxwell
equations in d-dimensions. These solutions are asymptotically locally flat,
de-Sitter, or anti-de Sitter space-times. The solutions we obtained depend on
two extra parameters other than the mass and the nut charge. These two
parameters are the electric charge, q and the electric potential at infinity,
V, which has a non-trivial contribution. We Analyze the conditions one can
impose to obtain Taub-Nut or Taub-Bolt space-times, including the
four-dimensional case. We found that in the nut case these conditions coincide
with that coming from the regularity of the one-form potential at the horizon.
Furthermore, the mass parameter for the higher dimensional solutions depends on
the nut charge and the electric charge or the potential at infinity.Comment: 11 pages, LaTe
Note on counterterms in asymptotically flat spacetimes
We consider in more detail the covariant counterterm proposed by Mann and
Marolf in asymptotically flat spacetimes. With an eye to specific practical
computations using this counterterm, we present explicit expressions in general
dimensions that can be used in the so-called `cylindrical cut-off' to
compute the action and the associated conserved quantities for an
asymptotically flat spacetime. As applications, we show how to compute the
action and the conserved quantities for the NUT-charged spacetime and for the
Kerr black hole in four dimensions.Comment: 13 pages, v. 2 added reference
Eguchi-Hanson Solitons in Odd Dimensions
We present a new class of solutions in odd dimensions to Einstein's equations
containing either a positive or negative cosmological constant. These solutions
resemble the even-dimensional Eguchi-Hanson-(A)dS metrics, with the added
feature of having Lorentzian signatures. They are asymptotic to
(A)dS. In the AdS case their energy is negative relative to that of
pure AdS. We present perturbative evidence in 5 dimensions that such metrics
are the states of lowest energy in their asymptotic class, and present a
conjecture that this is generally true for all such metrics. In the dS case
these solutions have a cosmological horizon. We show that their mass at future
infinity is less than that of pure dS.Comment: 26 pages, Late
Black strings with negative cosmological constant: inclusion of electric charge and rotation
We generalize the vacuum static black strings with negative cosmological
constant recently discussed in literature, by including an electromagnetic
field. These higher-dimensional configurations have no dependence on the
`compact' extra dimension, and their boundary topology is the product of time
and or . Rotating generalizations of the
even dimensional black string configurations are considered as well. Different
from the static, neutral case, no regular limit is found for a vanishing event
horizon radius. We explore numerically the general properties of such solutions
and, using a counterterm prescription, we compute their conserved charges and
discuss their thermodynamics. We find that the thermodynamics of the black
strings follows the pattern of the corresponding black hole solutions in AdS
backgrounds.Comment: 35 pages, 8 figures, final versio
Charged-rotating black holes and black strings in higher dimensional Einstein-Maxwell theory with a positive cosmological constant
We present arguments for the existence of charged, rotating black holes in
dimensions, with with a positive cosmological constant.
These solutions posses both, a regular horizon and a cosmological horizon of
spherical topology and have equal-magnitude angular momenta. They approach
asymptotically the de Sitter spacetime background. The counterpart equations
for are investigated, by assuming that the fields are independant of
the extra dimension , leading to black strings solutions. These solutions
are regular at the event horizon. The asymptotic form of the metric is not the
de Sitter form and exhibit a naked singularity at finite proper distance.Comment: 21 pages, 9 figure
Quasilocal formalism and thermodynamics of asymptotically flat black objects
We study the properties of 5-dimensional black objects by using the
renormalized boundary stress-tensor for locally asymptotically flat spacetimes.
This provides a more refined form of the quasilocal formalism which is useful
for a holographic interpretation of asymptotically flat gravity. We apply this
technique to examine the thermodynamic properties of black holes, black rings,
and black strings. The advantage of using this method is that we can go beyond
the `thin ring' approximation and compute the boundary stress tensor for any
general (thin or fat) black ring solution. We argue that the boundary stress
tensor encodes the necessarily information to distinguish between black objects
with different horizon topologies in the bulk. We also study in detail the susy
black ring and clarify the relation between the asymptotic charges and the
charges defined at the horizon. Furthermore, we obtain the balance condition
for `thin' dipole black rings.Comment: v2 clarifications on the advantage of using quasilocal formalism for
black rings added, CQG versio