scholarly journals Asymptotically flat black holes with scalar hair: A review

2015 ◽  
Vol 24 (09) ◽  
pp. 1542014 ◽  
Author(s):  
Carlos A. R. Herdeiro ◽  
Eugen Radu
Keyword(s):  
Scalar Field ◽  
State Of The Art ◽  
Energy Condition ◽  
Scalar Fields ◽  
Gauge Fields ◽  
Asymptotically Flat ◽  
The Status ◽  
Recent Developments ◽  
Flat Spacetimes ◽  
Scalar Hair

We consider the status of black hole (BH) solutions with nontrivial scalar fields but no gauge fields, in four-dimensional asymptotically flat spacetimes, reviewing both classical results and recent developments. We start by providing a simple illustration on the physical difference between BHs in electro-vacuum and scalar-vacuum. Next, we review no-scalar-hair theorems. In particular, we detail an influential theorem by Bekenstein and stress three key assumptions: (1) The type of scalar field equation; (2) the spacetime symmetry inheritance by the scalar field and (3) an energy condition. Then, we list regular (on and outside the horizon), asymptotically flat BH solutions with scalar hair, organizing them by the assumption which is violated in each case and distinguishing primary from secondary hair. We provide a table summary of the state-of-the-art.

scholarly journals SCALAR DEFORMATIONS OF SCHWARZSCHILD HOLES AND THEIR STABILITY

1998 ◽  
Vol 13 (05) ◽  
pp. 741-764 ◽  
Author(s):  
HELGE DENNHARDT ◽  
OLAF LECHTENFELD
Keyword(s):  
Scalar Field ◽  
Energy Condition ◽  
Linear Perturbation ◽  
Dominant Energy Condition ◽  
Stability Criteria ◽  
Field Equations ◽  
Effective Potentials ◽  
Scalar Hair ◽  
Linear Perturbation Theory ◽  
Scalar Field Equations

We construct two solutions of the minimally coupled Einstein-scalar field equations, representing regular deformations of Schwarzschild black holes by a self-interacting, static, scalar field. One solution features an exponentially decaying scalar field and a triple-well interaction potential; the other one is completely analytic and sprouts Coulomb-like scalar hair. Both evade the no-hair theorem by having partially negative potential, in conflict with the dominant energy condition. The linear perturbation theory around such backgrounds is developed in general, and yields stability criteria in terms of effective potentials for an analog Schrödinger problem. We can test for more than half of the perturbation modes, and our solutions prove to be stable against those.

Flat space holography

2008 ◽  
Vol 86 (4) ◽  
pp. 563-570
Author(s):  
R B Mann
Keyword(s):  
Field Theory ◽  
Flat Space ◽  
De Sitter ◽  
Spacetime Dimension ◽  
Asymptotically Flat ◽  
Conformal Field ◽  
Recent Developments ◽  
Concrete Realization ◽  
Flat Spacetimes ◽  
Spacelike Infinity

The implementation of holography in gravitational physics has its most concrete realization in the context of the anti-de Sitter/conformal field theory (AdS/CFT) correspondence conjecture, an implication of which is that counterterms from the boundary CFT can be understood as surface terms that render the variational principle finite and well-defined for the gravity theory in the bulk. I discuss recent developments that show how such gravitational counterterms can be deployed for asymptotically flat spacetimes in any spacetime dimension d ≥ 4. These actions yield conserved quantities at spacelike infinity that agree with the usual Arnowitt–Deser–Misner results but are more general. This approach removes the need for ill-defined background subtraction methods and suggests the possibility of obtaining a dual field theory to gravity theories in asymptotically flat spacetimes.PACS Nos.: 04.20.Ha, 04.60.–m, 11.25.Tq

scholarly journals GAUGE FIELDS, SCALARS, WARPED GEOMETRY, AND STRINGS

2001 ◽  
Vol 16 (05) ◽  
pp. 641-649 ◽  
Author(s):  
EVA SILVERSTEIN
Keyword(s):  
Scalar Fields ◽  
Point Of View ◽  
Fine Tuning ◽  
Gauge Fields ◽  
The Status ◽  
Holographic Duals ◽  
General Relativistic ◽  
Relativistic Description ◽  
M Theory

We review results on several interesting phenomena in warped compactifications of M theory, as presented at Strings 2000. The behavior of gauge fields in dimensional reduction from d+1 to d dimensions in various backgrounds is explained from the point of view of the holographic duals (and a point raised in the question session at the conference is addressed). We summarize the role of additional fields (in particular scalar fields) in 5d warped geometries in making it possible for Poincare-invariant domain wall solutions to exist to a nontrivial order in a controlled approximation scheme without fine-tuning of parameters in the 5d action (and comment on the status of the singularities arising in the general relativistic description of these solutions). Finally, we discuss briefly the emergence of excitations of wrapped branes in warped geometries whose effective thickness, as measured along the Poincare slices in the geometry, grows as the energy increases.

scholarly journals No hair theorem for massless scalar fields outside asymptotically flat horizonless reflecting compact stars

2019 ◽  
Vol 79 (10) ◽  
Author(s):  
Yan Peng
Keyword(s):  
Mathematical Proof ◽  
Scalar Fields ◽  
Compact Stars ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Spherically Symmetric ◽  
Massive Scalar ◽  
Asymptotically Flat ◽  
Scalar Hair ◽  
Rigorous Mathematical Proof

Abstract In a recent paper, Hod started a study on no scalar hair theorem for asymptotically flat spherically symmetric neutral horizonless reflecting compact stars. In fact, Hod’s approach only rules out massive scalar fields. In the present paper, for massless scalar fields outside neutral horizonless reflecting compact stars, we provide a rigorous mathematical proof on no hair theorem. We show that asymptotically flat spherically symmetric neutral horizonless reflecting compact stars cannot support exterior massless scalar field hairs.

scholarly journals WORMHOLES SUPPORTED BY SCALAR FIELDS WITH NEGATIVE KINETIC ENERGY

2009 ◽  
Vol 24 (27) ◽  
pp. 5007-5018 ◽  
Author(s):  
F. RAHAMAN ◽  
M. KALAM ◽  
K. A. RAHMAN
Keyword(s):  
Scalar Field ◽  
Kinetic Energy ◽  
Crucial Role ◽  
Energy Condition ◽  
Scalar Fields ◽  
Phantom Energy ◽  
Null Energy Condition ◽  
Kinetic Term ◽  
New Model ◽  
Higher Dimensional

We provide a new model of higher-dimensional wormholes supported by phantom energy derived from a scalar field with negative kinetic term. We have shown that the Averaged Null Energy Condition (ANEC) violating phantom energy can be reduced as desired. We have also noticed that dimension of the space–time plays a crucial role for measuring the ANEC violating matter needed.

Euclidean Quantum Wormholes with Scalar Fields

1997 ◽  
Vol 12 (20) ◽  
pp. 3517-3544 ◽  
Author(s):  
A. Carlini ◽  
D. H. Coule ◽  
D. M. Solomons
Keyword(s):  
Scalar Field ◽  
Perfect Fluid ◽  
Energy Condition ◽  
Classical Case ◽  
Scalar Fields ◽  
Closed Universe ◽  
Strong Energy Condition ◽  
Strong Energy ◽  
Fluid Matter ◽  
Effective String Theory

We consider the quantum analogs of Euclidean wormholes obtained by Carlini and Mijić (CM), who analytically continued recollapsing closed universe models. Using a perfect fluid matter source, we obtain asymptotically Euclidean (AE) wormholes when the strong energy condition is satisfied. Such wormholes are found to be consistent with the Hawking–Page (HP) conjecture for quantum wormholes as solutions of the Wheeler–DeWitt (WDW) equation. By simulating the equation of state of a perfect fluid with a real scalar field, quantum wormholes are also found when the strong energy condition is violated, although generally not AE. The non-AE solutions are interpreted as excited states of the quantum wormhole spectrum. Our results give support to the claim of HP that quantum wormhole solutions are a fairly general property of the WDW equation for various matter sources. Matter sources giving quantum wormholes could now include those expected in low energy effective string theory: a dilaton scalar field with exponential potential. This is unlike the classical case where such matter sources do not allow wormhole solutions. We finally contrast quantum wormhole solutions with other boundary conditions of quantum cosmology describing an inflationary earlier behavior and a resulting large Lorentzian universe phase.

scholarly journals Inside an asymptotically flat hairy black hole

2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
Óscar J. C. Dias ◽  
Gary T. Horowitz ◽  
Jorge E. Santos
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Scalar Field ◽  
Holographic Superconductor ◽  
Charged Scalar ◽  
General Argument ◽  
Asymptotically Flat ◽  
Charged Black Holes ◽  
Scalar Hair ◽  
Hairy Black Hole

Abstract We study the interior of a recently constructed family of asymptotically flat, charged black holes that develop (charged) scalar hair as one increases their charge at fixed mass. Inside the horizon, these black holes resemble the interior of a holographic superconductor. There are analogs of the Josephson oscillations of the scalar field, and the final Kasner singularity depends very sensitively on the black hole parameters near the onset of the instability. In an appendix, we give a general argument that Cauchy horizons cannot exist in a large class of stationary black holes with scalar hair.

Recycling and Reuse in the Roman Economy

2020 ◽  
Keyword(s):  
Building Materials ◽  
Computational Modelling ◽  
Late Antique ◽  
Roman Economy ◽  
Wide Range ◽  
The Status ◽  
Recent Developments ◽  
Methodological Approaches ◽  
First Time ◽  
Site Types

The recycling and reuse of materials and objects were extensive in the past, but have rarely been embedded into models of the economy; even more rarely has any attempt been made to assess the scale of these practices. Recent developments, including the use of large datasets, computational modelling, and high-resolution analytical chemistry, are increasingly offering the means to reconstruct recycling and reuse, and even to approach the thorny matter of quantification. Growing scholarly interest in the topic has also led to an increasing recognition of these practices from those employing more traditional methodological approaches, which are sometimes coupled with innovative archaeological theory. Thanks to these efforts, it has been possible for the first time in this volume to draw together archaeological case studies on the recycling and reuse of a wide range of materials, from papyri and textiles, to amphorae, metals and glass, building materials and statuary. Recycling and reuse occur at a range of site types, and often in contexts which cross-cut material categories, or move from one object category to another. The volume focuses principally on the Roman Imperial and late antique world, over a broad geographical span ranging from Britain to North Africa and the East Mediterranean. Last, but not least, the volume is unique in focusing upon these activities as a part of the status quo, and not just as a response to crisis.

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