208 research outputs found
Small Horizons
All near horizon geometries of supersymmetric black holes in a N=2, D=5
higher-derivative supergravity theory are classified. Depending on the choice
of near-horizon data we find that either there are no regular horizons, or
horizons exist and the spatial cross-sections of the event horizons are
conformal to a squashed or round S^3, S^1 * S^2, or T^3. If the conformal
factor is constant then the solutions are maximally supersymmetric. If the
conformal factor is not constant, we find that it satisfies a non-linear vortex
equation, and the horizon may admit scalar hair.Comment: 21 pages, latex. Typos corrected and reference adde
The FGK formalism for black p-branes in d dimensions
We present a generalization to an arbitrary number of spacetime (d) and
worldvolume (p+1) dimensions of the formalism proposed by Ferrara, Gibbons and
Kallosh to study black holes (p=0) in d=4 dimensions. We include the special
cases in which there can be dyonic and self- or anti-self-dual black branes.
Most of the results valid for 4-dimensional black holes (relations between
temperature, entropy and non-extremality parameter, and between entropy and
black-hole potential on the horizon) are straightforwardly generalized.
We apply the formalism to the case of black strings in N=2,d=5 supergravity
coupled to vector multiplets, in which the black-string potential can be
expressed in terms of the dual central charge and work out an explicit example
with one vector multiplet, determining supersymmetric and non-supersymmetric
attractors and constructing the non-extremal black-string solutions that
interpolate between them.Comment: 28 pages no figures; v2: some references adde
Small Hairy Black Holes in Global AdS Spacetime
We study small charged black holes in global AdS spacetime in the presence of
a charged massless minimally coupled scalar field. In a certain parameter range
these black holes suffer from well known superradiant instabilities. We
demonstrate that the end point of the resultant tachyon condensation process is
a hairy black hole which we construct analytically in a perturbative expansion
in the black hole radius. At leading order our solution is a small undeformed
RNAdS black hole immersed into a charged scalar condensate that fills the AdS
`box'. These hairy black hole solutions appear in a two parameter family
labelled by their mass and charge. Their mass is bounded from below by a
function of their charge; at the lower bound a hairy black hole reduces to a
regular horizon free soliton which can also be thought of as a nonlinear Bose
condensate. We compute the microcanonical phase diagram of our system at small
mass, and demonstrate that it exhibits a second order `phase transition'
between the RNAdS black hole and the hairy black hole phases.Comment: 68+1 pages, 18 figures, JHEP format. v2 : small typos corrected and a
reference adde
Constructing near-horizon geometries in supergravities with hidden symmetry
We consider the classification of near-horizon geometries in a general
two-derivative theory of gravity coupled to abelian gauge fields and uncharged
scalars in four and five dimensions, with one and two commuting rotational
symmetries respectively. Assuming that the theory of gravity reduces to a 3d
non-linear sigma model (as is typically the case for ungauged supergravities),
we show that the functional form of any such near-horizon geometry may be
determined. As an example we apply this to five dimensional minimal
supergravity. We also construct an example of a five parameter near-horizon
geometry solution to this theory with S^1 X S^2 horizon topology. We discuss
its relation to the near-horizon geometries of the yet to be constructed
extremal black rings with both electric and dipole charges.Comment: Latex, 30 pages. v2: discussion in section 5 modified and improved,
other minor changes, references adde
Supersymmetric Charged Clouds in AdS_5
We consider supersymmetric holographic flows that involve background gauge
fields dual to chemical potentials in the boundary field theory. We use a
consistent truncation of gauged N=8 supergravity in five dimensions and we give
a complete analysis of the supersymmetry conditions for a large family of
flows. We examine how the well-known supersymmetric flow between two fixed
points is modified by the presence of the chemical potentials and this yields a
new, completely smooth, solution that interpolates between two global AdS
spaces of different radii and with different values of the chemical potential.
We also examine some black-hole-like singular flows and a new
non-supersymmetric black hole solution. We comment on the interpretation of our
new solutions in terms of giant gravitons and discuss the implications of our
work for finding black-hole solutions in AdS geometries.Comment: 31 pages, 6 figures; minor corrections, updated reference
Pseudo-Killing Spinors, Pseudo-supersymmetric p-branes, Bubbling and Less-bubbling AdS Spaces
We consider Einstein gravity coupled to an n-form field strength in D
dimensions. Such a theory cannot be supersymmetrized in general, we
nevertheless propose a pseudo-Killing spinor equation and show that the AdS X
Sphere vacua have the maximum number of pseudo-Killing spinors, and hence are
fully pseudo-supersymmetric. We show that extremal p-branes and their
intersecting configurations preserve fractions of the pseudo-supersymmetry. We
study the integrability condition for general (D,n) and obtain the additional
constraints that are required so that the existence of the pseudo-Killing
spinors implies the Einstein equations of motion. We obtain new
pseudo-supersymmetric bubbling AdS_5 X S^5 spaces that are supported by a
non-self-dual 5-form. This demonstrates that non-supersymmegtric conformal
field theories may also have bubbling states of arbitrary droplets of free
fermions in the phase space. We also obtain an example of less-bubbling AdS
geometry in D=8, whose bubbling effects are severely restricted by the
additional constraint arising from the integrability condition.Comment: typos corrected, extra comments and references added, version
appeared in JHE
Black holes and black strings of N=2, d=5 supergravity in the H-FGK formalism
We study general classes and properties of extremal and non-extremal static
black-hole solutions of N=2, d=5 supergravity coupled to vector multiplets
using the recently proposed H-FGK formalism, which we also extend to static
black strings. We explain how to determine the integration constants and
physical parameters of the black-hole and black-string solutions. We derive
some model-independent statements, including the transformation of non-extremal
flow equations to the form of those for the extremal flow. We apply our methods
to the construction of example solutions (among others a new extremal string
solution of heterotic string theory on K_3 \times S^1). In the cases where we
have calculated it explicitly, the product of areas of the inner and outer
horizon of a non-extremal solution coincides with the square of the
moduli-independent area of the horizon of the extremal solution with the same
charges.Comment: 33 pages. Revised version: references added. No other change
Supergravity Solutions from Floating Branes
We solve the equations of motion of five-dimensional ungauged supergravity
coupled to three U(1) gauge fields using a floating-brane Ansatz in which the
electric potentials are directly related to the gravitational warp factors. We
find a new class of non-BPS solutions, that can be obtained linearly starting
from an Euclidean four-dimensional Einstein-Maxwell base. This class - the
largest known so far - reduces to the BPS and almost-BPS solutions in certain
limits. We solve the equations explicitly when the base space is given by the
Israel-Wilson metric, and obtain solutions describing non-BPS D6 and anti-D6
branes kept in equilibrium by flux. We also examine the action of spectral flow
on solutions with an Israel-Wilson base and show that it relates these
solutions to almost-BPS solutions with a Gibbons-Hawking base.Comment: 24 pages, 1 figur
Schr\"odinger Deformations of AdS_3 x S^3
We study Schr\"odinger invariant deformations of the AdS_3 x S^3 x T^4 (or
K3) solution of IIB supergravity and find a large class of solutions with
integer and half-integer dynamical exponents. We analyze the supersymmetries
preserved by our solutions and find an infinite number of solutions with four
supersymmetries. We study the solutions holographically and find that the dual
D1-D5 (or F1-NS5) CFT is deformed by irrelevant operators of spin one and two.Comment: 23 page
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