46 research outputs found
Rotating Circular Strings, and Infinite Non-Uniqueness of Black Rings
We present new self-gravitating solutions in five dimensions that describe
circular strings, i.e., rings, electrically coupled to a two-form potential (as
e.g., fundamental strings do), or to a dual magnetic one-form. The rings are
prevented from collapsing by rotation, and they create a field analogous to a
dipole, with no net charge measured at infinity. They can have a regular
horizon, and we show that this implies the existence of an infinite number of
black rings, labeled by a continuous parameter, with the same mass and angular
momentum as neutral black rings and black holes. We also discuss the solution
for a rotating loop of fundamental string. We show how more general rings arise
from intersections of branes with a regular horizon (even at extremality),
closely related to the configurations that yield the four-dimensional black
hole with four charges. We reproduce the Bekenstein-Hawking entropy of a large
extremal ring through a microscopic calculation. Finally, we discuss some
qualitative ideas for a microscopic understanding of neutral and dipole black
rings.Comment: 31 pages, 7 figures. v2: minor changes, added reference. v3:
erroneous values of T_{ww} (eq.(3.39)) and n_p (eq.(5.20)) corrected, and
accompanying discussion amended. In the journal version these corrections
appear as an appended erratum. No major changes involve
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
Caged Black Holes: Black Holes in Compactified Spacetimes I -- Theory
In backgrounds with compact dimensions there may exist several phases of
black objects including the black-hole and the black-string. The phase
transition between them raises puzzles and touches fundamental issues such as
topology change, uniqueness and Cosmic Censorship. No analytic solution is
known for the black hole, and moreover, one can expect approximate solutions
only for very small black holes, while the phase transition physics happens
when the black hole is large. Hence we turn to numerical solutions. Here some
theoretical background to the numerical analysis is given, while the results
will appear in a forthcoming paper. Goals for a numerical analysis are set. The
scalar charge and tension along the compact dimension are defined and used as
improved order parameters which put both the black hole and the black string at
finite values on the phase diagram. Predictions for small black holes are
presented. The differential and the integrated forms of the first law are
derived, and the latter (Smarr's formula) can be used to estimate the ``overall
numerical error''. Field asymptotics and expressions for physical quantities in
terms of the numerical ones are supplied. Techniques include ``method of
equivalent charges'', free energy, dimensional reduction, and analytic
perturbation for small black holes.Comment: 23 pages. v3: version to be published in PRD, 3 references adde
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.
Rotating nonuniform black string solutions
We explore via linearized perturbation theory the Gregory-Laflamme
instability of rotating black strings with equal magnitude angular momenta. Our
results indicate that the Gregory-Laflamme instability persists up to
extremality for all even dimensions between six and fourteen. We construct
rotating nonuniform black strings with two equal magnitude angular momenta in
six dimensions. We see a first indication for the occurrence of a topology
changing transition, associated with such rotating nonuniform black strings.
Charged nonuniform black string configurations in heterotic string theory are
also constructed by employing a solution generation technique.Comment: 36 pages, 10 figures, final versio
Intersecting D-Branes in ten and six dimensions
We show how, via -duality, intersecting -Brane configurations in ten
(six) dimensions can be obtained from the elementary -Brane configurations
by embedding a Type IIB -Brane into a Type IIB Nine-Brane (Five-Brane) and
give a classification of such configurations. We show that only a very specific
subclass of these configurations can be realized as (supersymmetric) solutions
to the equations of motion of IIA/IIB supergravity. Whereas the elementary
-brane solutions in are characterized by a single harmonic function,
those in contain two independent harmonic functions and may be viewed as
the intersection of two elementary -branes. Using
string/string/string triality in six dimensions we show that the heterotic
version of the elementary -Brane solutions correspond in ten
dimensions to intersecting Neveu-Schwarz/Neveu-Schwarz (NS/NS) strings or
five-branes and their -duals. We comment on the implications of our results
in other than ten and six dimensions.Comment: 18 pages, Latex, (substantial changes in section 2
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
How to Stop (Worrying and Love) the Bubble: Boundary Changing Solutions
We discover that a class of bubbles of nothing are embedded as time dependent
scaling limits of previous spacelike-brane solutions. With the right initial
conditions, a near-bubble solution can relax its expansion and open the compact
circle. Thermodynamics of the new class of solutions is discussed and the
relationships between brane/flux transitions, tachyon condensation and
imaginary D-branes are outlined. Finally, a related class of simultaneous
connected S-branes are also examined.Comment: 47 pages; v2 introduction to Weyl cards added, comments added,
references added, typos corrected, matches JHEP versio
Lodged in the throat: Internal infinities and AdS/CFT
In the context of AdS3/CFT2, we address spacetimes with a certain sort of
internal infinity as typified by the extreme BTZ black hole. The internal
infinity is a null circle lying at the end of the black hole's infinite throat.
We argue that such spacetimes may be described by a product CFT of the form
CFT-L * CFT-R, where CFT-R is associated with the asymptotically AdS boundary
while CFT-L is associated with the null circle. Our particular calculations
analyze the CFT dual of the extreme BTZ black hole in a linear toy model of
AdS3/CFT2. Since the BTZ black hole is a quotient of AdS3, the dual CFT state
is a corresponding quotient of the CFT vacuum state. This state turns out to
live in the aforementioned product CFT. We discuss this result in the context
of general issues of AdS/CFT duality and entanglement entropy.Comment: 11 pages, 2 figures; v2 - some typos corrected, minor revision
Negative Energy in String Theory and Cosmic Censorship Violation
We find asymptotically anti de Sitter solutions in N=8 supergravity which
have negative total energy. This is possible since the boundary conditions
required for the positive energy theorem are stronger than those required for
finite mass (and allowed by string theory). But stability of the anti de Sitter
vacuum is still ensured by the positivity of a modified energy, which includes
an extra surface term. Some of the negative energy solutions describe classical
evolution of nonsingular initial data to naked singularities. Since there is an
open set of such solutions, cosmic censorship is violated generically in
supergravity. Using the dual field theory description, we argue that these
naked singularities will be resolved in the full string theory.Comment: 23 pages, 2 figures, v2: argument for forming naked singularities
clarified, references adde