468 research outputs found
Dynamics and Stability of Black Rings
We examine the dynamics of neutral black rings, and identify and analyze a
selection of possible instabilities. We find the dominating forces of very thin
black rings to be a Newtonian competition between a string-like tension and a
centrifugal force. We study in detail the radial balance of forces in black
rings, and find evidence that all fat black rings are unstable to radial
perturbations, while thin black rings are radially stable. Most thin black
rings, if not all of them, also likely suffer from Gregory-Laflamme
instabilities. We also study simple models for stability against
emission/absorption of massless particles. Our results point to the conclusion
that most neutral black rings suffer from classical dynamical instabilities,
but there may still exist a small range of parameters where thin black rings
are stable. We also discuss the absence of regular real Euclidean sections of
black rings, and thermodynamics in the grand-canonical ensemble.Comment: 39 pages, 17 figures; v2: conclusions concerning radial stability
corrected + new appendix + refs added; v3: additional comments regarding
stabilit
A black ring with a rotating 2-sphere
We present a solution of the vacuum Einstein's equations in five dimensions
corresponding to a black ring with horizon topology S^1 x S^2 and rotation in
the azimuthal direction of the S^2. This solution has a regular horizon up to a
conical singularity, which can be placed either inside the ring or at infinity.
This singularity arises due to the fact that this black ring is not balanced.
In the infinite radius limit we correctly reproduce the Kerr black string, and
taking another limit we recover the Myers-Perry black hole with a single
angular momentum.Comment: 10 page
On smoothness of Black Saturns
We prove smoothness of the domain of outer communications (d.o.c.) of the
Black Saturn solutions of Elvang and Figueras. We show that the metric on the
d.o.c. extends smoothly across two disjoint event horizons with topology R x
S^3 and R x S^1 x S^2. We establish stable causality of the d.o.c. when the
Komar angular momentum of the spherical component of the horizon vanishes, and
present numerical evidence for stable causality in general.Comment: 47 pages, 5 figure
Three Charge Supertubes in Type IIB Plane Wave Backgrounds
We deform the supersymmetric black ring of five dimensional supergravity
coupled to N-1 vector multiplets to obtain an asymptotically Goedel
supersymmetric black ring. For the U(1)^3 model we lift this solution to obtain
a three charge D1-D5-P supertube which asymptotes to a 1/2 supersymmetric plane
wave of Type IIB supergravity. Further, we also show how one may deform the
asymptotically flat three charge supertube of type IIB, in the special case of
vanishing KK dipole charge, to a three charge supertube which asymptotes to the
maximally supersymmetric plane wave.Comment: 1+14 pages, JHEP
Black Rings in Taub-NUT and D0-D6 interactions
We analyze the dynamics of neutral black rings in Taub-NUT spaces and their
relation to systems of D0 and D6 branes in the supergravity approximation. We
employ several recent techniques, both perturbative and exact, to construct
solutions in which thermal excitations of the D0-branes can be turned on or
off, and the D6-brane can have -fluxes turned on or off in its worldvolume.
By explicit calculation of the interaction energy between the D0 and D6 branes,
we can study equilibrium configurations and their stability. We find that
although D0 and D6 branes (in the absence of fields, and at zero
temperature) repeal each other at non-zero separation, as they get together
they go over continuosly to an unstable bound state of an extremal singular
Kaluza-Klein black hole. We also find that, for -fields larger than a
critical value, or sufficiently large thermal excitation, the D0 and D6 branes
form stable bound states. The bound states with thermally excited D0 branes are
black rings in Taub-NUT, and we provide an analysis of their phase diagram.Comment: 50 pages, 8 figures; v3: minor changes and references added; v4:
improved figs. 7 and 8, matches with published versio
A Black Ring with two Angular Momenta in Taub-NUT
We use the recently-constructed explicit duality transformation that relates
a rotating anti-D6-D4-D2-D0 black hole solution to a rotating M5-M2-P black
string to construct a non-supersymmetric black ring in Taub-NUT that has two
angular momenta, as well as M2 charges and M5 dipole moments. This is the first
black ring solution that has both dipole charges and rotation along the S^2 of
the horizon, and hence can be thought of as the "Pomeransky-Senkov" version of
the M5-M2 black ring in Taub-NUT. Its physics should provide a testing ground
for the applicability of the blackfold approach to charged rotating black
branes, and should elucidate the phase space of charged dipole rings in various
backgrounds.Comment: 20 pages, LaTe
Non-supersymmetric black rings as thermally excited supertubes
We construct a seven-parameter family of supergravity solutions that describe
non-supersymmetric black rings and black tubes with three charges, three
dipoles and two angular momenta. The black rings have regular horizons and
non-zero temperature. They are naturally interpreted as the supergravity
descriptions of thermally excited configurations of supertubes, specifically of
supertubes with two charges and one dipole, and of supertubes with three
charges and two dipoles. In order to fully describe thermal excitations near
supersymmetry of the black supertubes with three charges and three dipoles a
more general family of black ring solutions is required.Comment: 35 pages. v2: ref added and minor typo correcte
Quasilocal equilibrium condition for black ring
We use the conservation of the renormalized boundary stress-energy tensor to
obtain the equilibrium condition for a general (thin or fat) black ring
solution. We also investigate the role of the spatial stress in the
thermodynamics of deformation within the quasilocal formalism of Brown and York
and discuss the relation with other methods. In particular, we discuss the
quantum statistical relation for the unbalanced black ring solution.Comment: v2: refs. added, matches the published versio
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