107 research outputs found
Conformally coupled scalar black holes admit a flat horizon due to axionic charge
Static, charged black holes in the presence of a negative cosmological
constant and with a planar horizon are found in four dimensions. The solutions
have scalar secondary hair. We claim that these constitute the planar version
of the Martinez-Troncoso-Zanelli black holes, only known up to now for a curved
event horizon in four dimensions. Their planar version is rendered possible due
to the presence of two, equal and homogeneously distributed, axionic charges
dressing the flat horizon. The solutions are presented in the conformal and
minimal frame and their basic properties and thermodynamics analysed.
Entertaining recent applications to holographic superconductors, we expose two
branches of solutions: the undressed axionic Reissner-Nordstrom-AdS black hole,
and the novel black hole carrying secondary hair. We show that there is a
critical temperature at which the (bald) axionic Reissner-Nordstrom-AdS black
hole undergoes a second order phase transition to the hairy black hole
spontaneously acquiring scalar hair.Comment: 21 pages, 4 figure
Integrability in conformally coupled gravity: Taub-NUT spacetimes and rotating black holes
We consider four dimensional stationary and axially symmetric spacetimes for
conformally coupled scalar-tensor theories. We show that, in analogy to the
Lewis-Papapetrou problem in General Relativity (GR), the theory at hand can be
recast in an analogous integrable form. We give the relevant rod formalism,
introduced by Weyl for vacuum GR, explicitly giving the rod structure of the
black hole of Bocharova et al. and Bekenstein (BBMB), in complete analogy to
the Schwarzschild solution. The additional scalar field is shown to play the
role of an extra Weyl potential. We then employ the Ernst method as a concrete
solution generating example to obtain the Taub-NUT version of the BBMB hairy
black hole, with or without a cosmological constant. We show that the anti-de
Sitter hyperbolic version of this solution is free of closed timelike curves
that plague usual Taub-NUT metrics, and thus consists of a rotating,
asymptotically locally anti-de Sitter black hole. This stationary solution has
no curvature singularities whatsoever in the conformal frame, and the NUT
charge is shown here to regularize the central curvature singularity of the
corresponding static black hole. Given our findings we discuss the anti-de
Sitter hyperbolic version of Taub-NUT in four dimensions, and show that the
curvature singularity of the NUT-less solution is now replaced by a neighboring
chronological singularity screened by horizons. We argue that the properties of
this rotating black hole are very similar to those of the rotating BTZ black
hole in three dimensions.Comment: 27 pages, 1 figur
AdS black holes with arbitrary scalar coupling
A general class of axionic and electrically charged black holes for a
self-interacting scalar field nonminimally coupled to Einstein gravity with a
negative cosmological constant is presented. These solutions are the first
examples of black holes with an arbitrary nonminimal coupling in four
dimensions. Moreover, due to the presence of two three-forms fields, the
topology of the horizon of these black holes is planar. We discuss some
properties of these solutions electing particular values of the nonminimal
coupling parameter. A special case arises when , for which the
gravitational field is confined in a region close to the event horizon. We also
show that these black holes emerge from stealth AdS configurations as the
axionic fields are switched on, and that they can be generated through a
Kerr-Schild transformation. Finally, in the appendix, we extend these results
to arbitrary dimension.Comment: 23 page
Black Rings in (Anti)-deSitter space
We construct solutions for thin black rings in Anti-deSitter and deSitter
spacetimes using approximate methods. Black rings in AdS exist with arbitrarily
large radius and satisfy a bound |J| \leq LM, which they saturate as their
radius becomes infinitely large. For angular momentum near the maximum, they
have larger area than rotating AdS black holes. Thin black rings also exist in
deSitter space, with rotation velocities varying between zero and a maximum,
and with a radius that is always strictly below the Hubble radius. Our general
analysis allows us to include black Saturns as well, which we discuss briefly.
We present a simple physical argument why supersymmetric AdS black rings must
not be expected: they do not possess the necessary pressure to balance the AdS
potential. We discuss the possible existence or absence of `large AdS black
rings' and their implications for a dual hydrodynamic description. An analysis
of the physical properties of rotating AdS black holes is also included.Comment: 38 pages, 6 figures. v2: changes in terminology, refs added. v3:
minor improvements, refs added, published versio
AdS/Ricci-flat correspondence
We present a comprehensive analysis of the AdS/Ricci-flat correspondence, a
map between a class of asymptotically locally AdS spacetimes and a class of
Ricci-flat spacetimes. We provide a detailed derivation of the map, discuss a
number of extensions and apply it to a number of important examples, such as
AdS on a torus, AdS black branes and fluids/gravity metrics. In particular, the
correspondence links the hydrodynamic regime of asymptotically flat black
-branes or the Rindler fluid with that of AdS. It implies that this class of
Ricci-flat spacetimes inherits from AdS a generalized conformal symmetry and
has a holographic structure. We initiate the discussion of holography by
analyzing how the map acts on boundary conditions and holographic 2-point
functions.Comment: v3: Minor edits, references added, matches published versio
Chronology Protection in anti-de Sitter
We consider 1/2 BPS excitations of AdS(5)xS(5) geometries in type IIB string
theory that can be mapped into free fermion configurations according to the
prescription of Lin, Lunin and Maldacena (LLM). It is shown that whenever the
fermionic probability density exceeds one or is negative, closed timelike
curves appear in the bulk. A violation of the Pauli exclusion principle in the
phase space of the fermions is thus intimately related to causality violation
in the dual geometries.Comment: 4 pages, 1 figure. v2: clarifications on the proof and comments on
curvature singularity added. v3: final version to appear in Class. Quantum
Gra
AdS/Ricci-flat correspondence and the Gregory-Laflamme instability
We show that for every asymptotically anti–de Sitter (AdS) solution compactified on a torus there is a corresponding Ricci-flat solution obtained by replacing the torus by a sphere, performing a Weyl rescaling of the metric and appropriately analytically continuing the dimension of the torus/sphere (as in generalized dimensional reduction). In particular, it maps Minkowski spacetime to AdS on a torus, the holographic stress energy tensor of AdS to the stress energy tensor due to a brane localized in the interior of spacetime and AdS black branes to (asymptotically flat) Schwarzschild black branes. Applying it to the known solutions describing the hydrodynamic regime in AdS/CFT, we derive the hydrodynamic stress tensor of asymptotically flat black branes to second order, which is constrained by the parent conformal symmetry. We compute the dispersion relation of the Gregory-Laflamme unstable modes through cubic order in the wave number, finding remarkable agreement with numerical data. In the case of no transverse sphere, AdS black branes are mapped to Rindler spacetime and the second-order transport coefficients of the fluid dual to Rindler spacetime are recovered
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