272 research outputs found
New nonuniform black string solutions
We present nonuniform vacuum black strings in five and six spacetime
dimensions. The conserved charges and the action of these solutions are
computed by employing a quasilocal formalism. We find qualitative agreement of
the physical properties of nonuniform black strings in five and six dimensions.
Our results offer further evidence that the black hole and the black string
branches merge at a topology changing transition. We generate black string
solutions of the Einstein-Maxwell-dilaton theory by using a Harrison
transformation. We argue that the basic features of these solutions can be
derived from those of the vacuum black string configurations.Comment: 30 pages, 12 figures; v2: more details on numerical method,
references added; v3: references added, minor revisions, version accepted by
journa
Three-Charge Black Holes on a Circle
We study phases of five-dimensional three-charge black holes with a circle in
their transverse space. In particular, when the black hole is localized on the
circle we compute the corrections to the metric and corresponding
thermodynamics in the limit of small mass. When taking the near-extremal limit,
this gives the corrections to the constant entropy of the extremal three-charge
black hole as a function of the energy above extremality. For the partial
extremal limit with two charges sent to infinity and one finite we show that
the first correction to the entropy is in agreement with the microscopic
entropy by taking into account that the number of branes shift as a consequence
of the interactions across the transverse circle. Beyond these analytical
results, we also numerically obtain the entire phase of non- and near-extremal
three- and two-charge black holes localized on a circle. More generally, we
find in this paper a rich phase structure, including a new phase of
three-charge black holes that are non-uniformly distributed on the circle. All
these three-charge black hole phases are found via a map that relates them to
the phases of five-dimensional neutral Kaluza-Klein black holes.Comment: 58 pages, 10 figures; v2: Corrected typos, version appearing in JHE
Sequences of Bubbles and Holes: New Phases of Kaluza-Klein Black Holes
We construct and analyze a large class of exact five- and six-dimensional
regular and static solutions of the vacuum Einstein equations. These solutions
describe sequences of Kaluza-Klein bubbles and black holes, placed alternately
so that the black holes are held apart by the bubbles. Asymptotically the
solutions are Minkowski-space times a circle, i.e. Kaluza-Klein space, so they
are part of the (\mu,n) phase diagram introduced in hep-th/0309116. In
particular, they occupy a hitherto unexplored region of the phase diagram,
since their relative tension exceeds that of the uniform black string. The
solutions contain bubbles and black holes of various topologies, including
six-dimensional black holes with ring topology S^3 x S^1 and tuboid topology
S^2 x S^1 x S^1. The bubbles support the S^1's of the horizons against
gravitational collapse. We find two maps between solutions, one that relates
five- and six-dimensional solutions, and another that relates solutions in the
same dimension by interchanging bubbles and black holes. To illustrate the
richness of the phase structure and the non-uniqueness in the (\mu,n) phase
diagram, we consider in detail particular examples of the general class of
solutions.Comment: 71 pages, 22 figures, v2: Typos fixed, comment added in sec. 5.
Uniqueness Theorem for Black Hole Space-Times with Multiple Disconnected Horizons
We show uniqueness of stationary and asymptotically flat black hole
space-times with multiple disconnected horizons and with two rotational Killing
vector fields in the context of five-dimensional minimal supergravity
(Einstein-Maxwell-Chern-Simons gravity). The novelty in this work is the
introduction in the uniqueness theorem of intrinsic local charges measured near
each horizon as well as the measurement of local fluxes besides the asymptotic
charges that characterize a particular solution. A systematic method of
defining the boundary conditions on the fields that specify a black hole
space-time is given based on the study of its rod structure (domain structure).
Also, an analysis of known solutions with disconnected horizons is carried out
as an example of an application of this theorem.Comment: 28 pages, 5 figures. v3: Further improvements on uniqueness theorem,
Lemma introduced for clarity of derivation, new quantities introduced to
treat special case with zero flux, refs. added, typos fixe
Formation of Five-Dimensional String Solutions from the Gravitational Collapse
We study the formation of five-dimensional string solutions including the
Gregory-Laflamme (GL) black string, the Kaluza-Klein (KK) bubble, and the
geometry with a naked singularity from the gravitational collapse. The interior
solutions of five-dimensional Einstein equations describe collapsing
non-isotropic matter clouds. It is shown that the matter cloud always forms the
GL black string solution while the KK bubble solution cannot be formed. The
numerical study seems to suggest that the collapsing matter forms the
geometries with timelike naked curvature singularities, which should be taken
cautiously as the general relativity is not reliable in the strong curvature
regime.Comment: 17 pages, 10 figures, LaTeX, to appear in Class. Quant. Grav., a
appendix and some discussions added, title change
On non-uniform smeared black branes
We investigate charged dilatonic black -branes smeared on a transverse
circle. The system can be reduced to neutral vacuum black branes, and we
perform static perturbations for the reduced system to construct non-uniform
solutions. At each order a single master equation is derived, and the
Gregory-Laflamme critical wavelength is determined. Based on the non-uniform
solutions, we discuss thermodynamic properties of this system and argue that in
a microcanonical ensemble the non-uniform smeared branes are entropically
disfavored even near the extremality, if the spacetime dimension is , which is the critical dimension for the vacuum case. However, the critical
dimension is not universal. In a canonical ensemble the vacuum non-uniform
black branes are thermodynamically favorable at , whereas the
non-uniform smeared branes are favorable at near the extremality.Comment: 24 pages, 2 figures; v2: typos corrected, submitted to
Class.Quant.Gra
Small Black Holes on Cylinders
We find the metric of small black holes on cylinders, i.e. neutral and static
black holes with a small mass in d-dimensional Minkowski-space times a circle.
The metric is found using an ansatz for black holes on cylinders proposed in
hep-th/0204047. We use the new metric to compute corrections to the
thermodynamics which is seen to deviate from that of the (d+1)-dimensional
Schwarzschild black hole. Moreover, we compute the leading correction to the
relative binding energy which is found to be non-zero. We discuss the
consequences of these results for the general understanding of black holes and
we connect the results to the phase structure of black holes and strings on
cylinders.Comment: 23 pages, 1 figure. v2: typos corrected, introduction expanded, v3:
presentation of sections 2 and 3 reordered and improved, explanatory remarks
added, refs adde
New Phases of Near-Extremal Branes on a Circle
We study the phases of near-extremal branes on a circle, by which we mean
near-extremal branes of string theory and M-theory with a circle in their
transverse space. We find a map that takes any static and neutral Kaluza-Klein
black hole, i.e. any static and neutral black hole on Minkowski-space times a
circle M^d x S^1, and map it to a corresponding solution for a near-extremal
brane on a circle. The map is derived using first a combined boost and
U-duality transformation on the Kaluza-Klein black hole, transforming it to a
solution for a non-extremal brane on a circle. The resulting solution for a
near-extremal brane on a circle is then obtained by taking a certain
near-extremal limit. As a consequence of the map, we can transform the neutral
non-uniform black string branch into a new non-uniform phase of near-extremal
branes on a circle. Furthermore, we use recently obtained analytical results on
small black holes in Minkowski-space times a circle to get new information
about the localized phase of near-extremal branes on a circle. This gives in
turn predictions for the thermal behavior of the non-gravitational theories
dual to these near-extremal branes. In particular, we give predictions for the
thermodynamics of supersymmetric Yang-Mills theories on a circle, and we find a
new stable phase of (2,0) Little String Theory in the canonical ensemble for
temperatures above its Hagedorn temperature.Comment: 72 pages, 5 figures. v2: Typos fixed, refs. added. v3: Sec. 3.2 fixe
Thermodynamics of Squashed Kaluza-Klein Black Holes and Black Strings -- A Comparison of Reference Backgrounds --
We investigate thermodynamics constructed on different background reference
spacetimes for squashed Kaluza-Klein (SqKK) black hole and electrically charged
black string in five-dimensional Einstein-Maxwell system. Two spacetimes are
possible to be reference spacetimes giving finite gravitational classical
actions: one is four-dimensional Minkowski times a circle and the other is the
KK monopole. The boundary of the SqKK black hole can not be matched perfectly
to that of the former reference spacetime because of the difference in
topology. However, the resultant classical action coincides with that
calculated by the counterterm subtraction scheme. The boundary of the KK
monopole has the same topology with that of the SqKK black hole and can be
matched to the boundary of the black hole perfectly. The resultant action takes
different value from the result given by using the former reference spacetime.
After a brief review of thermodynamic quantities of the black hole solutions,
we calculate thermodynamic potentials relevant for several thermodynamic
environments. The most stable state is different for each environment: For
example, the KK monopole is the most stable state in isothermal environment
with fixed gravitational tension. On the other hand, when the size of the
extra-dimension is fixed, the Minkowski times a circle is the most stable. It
is shown that these two spacetimes can be reference spacetimes of the
five-dimensional black string.Comment: 28 pages; references added, typo corrected;version accepted for
publication in Class. Quantum Gra
New Horizons for Black Holes and Branes
We initiate a systematic scan of the landscape of black holes in any
spacetime dimension using the recently proposed blackfold effective worldvolume
theory. We focus primarily on asymptotically flat stationary vacuum solutions,
where we uncover large classes of new black holes. These include helical black
strings and black rings, black odd-spheres, for which the horizon is a product
of a large and a small sphere, and non-uniform black cylinders. More exotic
possibilities are also outlined. The blackfold description recovers correctly
the ultraspinning Myers-Perry black holes as ellipsoidal even-ball
configurations where the velocity field approaches the speed of light at the
boundary of the ball. Helical black ring solutions provide the first instance
of asymptotically flat black holes in more than four dimensions with a single
spatial U(1) isometry. They also imply infinite rational non-uniqueness in
ultraspinning regimes, where they maximize the entropy among all stationary
single-horizon solutions. Moreover, static blackfolds are possible with the
geometry of minimal surfaces. The absence of compact embedded minimal surfaces
in Euclidean space is consistent with the uniqueness theorem of static black
holes.Comment: 54 pages, 7 figures; v2 added references, added comments in the
subsection discussing the physical properties of helical black rings; v3
added references, fixed minor typo
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