Spherically symmetric systems of fields and black holes. III. Positivity of energy and of a new type Euclidean action

1984 ◽  
Vol 30 (6) ◽  
pp. 1185-1193 ◽  
Author(s):  
P. Hajicek
Keyword(s):  
Black Holes ◽  
Spherically Symmetric ◽  
New Type ◽  
Euclidean Action ◽  
Symmetric Systems

scholarly journals COLD BLACK HOLES AND CONFORMAL CONTINUATIONS

2008 ◽  
Vol 17 (01) ◽  
pp. 25-42 ◽  
Author(s):  
K. A. BRONNIKOV ◽  
M. S. CHERNAKOVA ◽  
J. C. FABRIS ◽  
N. PINTO-NETO ◽  
M. E. RODRIGUES
Keyword(s):  
Black Holes ◽  
Scalar Field ◽  
Infinite Horizon ◽  
Einstein Gravity ◽  
Spherically Symmetric ◽  
Four Dimensions ◽  
Phantom Scalar ◽  
New Type ◽  
Theories Of Gravity ◽  
Phantom Scalar Field

We study Einstein gravity minimally coupled to a scalar field in a static, spherically symmetric space–time in four dimensions. Black hole solutions are shown to exist for a phantom scalar field whose kinetic energy is negative. These "scalar black holes" have an infinite horizon area and zero Hawking temperature and are termed "cold black holes" (CBHs). The relevant explicit solutions are well known in the massless case (the so-called anti-Fisher solution), and we have found a particular example of a CBH with a nonzero potential V(ϕ). All CBHs with V(ϕ) ≢ 0 are shown to behave near the horizon, quite similarly to those with a massless field. The above solutions can be converted by a conformal transformation to Jordan frames of a general class of scalar–tensor theories of gravity, but CBH horizons in one frame are in many cases converted to singularities in the other, which gives rise to a new type of conformal continuation.

Perturbations of spherically symmetric black holes

1980 ◽  
Vol 77 (1) ◽  
pp. 7-8
Author(s):  
Basilis C. Xanthopoulos
Keyword(s):  
Black Holes ◽  
Spherically Symmetric

Boundary conditions for Maxwell fields in Kerr-AdS spacetimes

2016 ◽  
Vol 25 (09) ◽  
pp. 1641011 ◽  
Author(s):  
Mengjie Wang
Keyword(s):  
Black Holes ◽  
Angular Momentum ◽  
Boundary Conditions ◽  
Energy Flux ◽  
Momentum Flux ◽  
De Sitter ◽  
Perturbative Methods ◽  
Flux Boundary Conditions ◽  
Maxwell Fields ◽  
New Type

Perturbative methods are useful to study the interaction between black holes and test fields. The equation for a perturbation itself, however, is not complete to study such a composed system if we do not assign physically relevant boundary conditions. Recently we have proposed a new type of boundary conditions for Maxwell fields in Kerr-anti-de Sitter (Kerr-AdS) spacetimes, from the viewpoint that the AdS boundary may be regarded as a perfectly reflecting mirror, in the sense that energy flux vanishes asymptotically. In this paper, we prove explicitly that a vanishing energy flux leads to a vanishing angular momentum flux. Thus, these boundary conditions may be dubbed as vanishing flux boundary conditions.

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