scholarly journals No nonminimally coupled massless scalar hair for spherically symmetric neutral reflecting stars

2017 ◽  
Vol 96 (2) ◽  
Author(s):  
Shahar Hod
Keyword(s):  
Massless Scalar ◽  
Spherically Symmetric ◽  
Scalar Hair

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 Janis–Newman–Winicour and Wyman Solutions are the Same

1997 ◽  
Vol 12 (27) ◽  
pp. 4831-4835 ◽  
Author(s):  
K. S. Virbhadra
Keyword(s):  
Exact Solution ◽  
Scalar Field ◽  
Total Energy ◽  
Space Time ◽  
Massless Scalar ◽  
Spherically Symmetric ◽  
Scalar Equations

We show that the well-known most general static and spherically symmetric exact solution to the Einstein-massless scalar equations given by Wyman is the same as one found by Janis, Newman and Winicour several years ago. We obtain the energy associated with this space–time and find that the total energy for the case of the purely scalar field is zero.

scholarly journals Bondi accretion in the spherically symmetric Johannsen–Psaltis spacetime

2019 ◽  
Vol 79 (11) ◽  
Author(s):  
Anslyn J. John ◽  
Chris Z. Stevens
Keyword(s):  
Accretion Rate ◽  
Kerr Metric ◽  
Spherically Symmetric ◽  
Gravitational Acceleration ◽  
Symmetric Spacetimes ◽  
Spherically Symmetric Spacetimes ◽  
Scalar Hair ◽  
Relativistic Analysis ◽  
Modified Theory ◽  
Static Spherically Symmetric Spacetimes

AbstractThe Johannsen–Psaltis spacetime explicitly violates the no-hair theorem. It describes rotating black holes with scalar hair in the form of parametric deviations from the Kerr metric. In principle, black hole solutions in any modified theory of gravity could be written in terms of the Johannsen–Psaltis metric. We study the accretion of gas onto a static limit of this spacetime. We utilise a recently proposed pseudo–Newtonian formulation of the dynamics around arbitrary static, spherically symmetric spacetimes. We obtain a potential that generalises the Paczyński–Wiita potential to the static Johannsen–Psaltis metric. We also perform a fully relativistic analysis of the geodesic equations in the static Johannsen–Psaltis spacetime. We find that positive (negative) values of the scalar hair parameter, $$\epsilon _{3}$$ϵ3, lower (raise) the accretion rate. Similarly, positive (negative) values of $$\epsilon _{3}$$ϵ3 reduce (increase) the gravitational acceleration of radially infalling massive particles.

scholarly journals ONCE AGAIN ON THIN-SHELL WORMHOLES IN SCALAR–TENSOR GRAVITY

2009 ◽  
Vol 24 (20) ◽  
pp. 1559-1564 ◽  
Author(s):  
KIRILL A. BRONNIKOV ◽  
ALEXEI A. STAROBINSKY
Keyword(s):  
Thin Shell ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Spherically Symmetric ◽  
Shell Surface ◽  
Symmetric Spacetimes ◽  
Tensor Theory ◽  
Thin Shell Wormholes ◽  
Spherically Symmetric Spacetimes ◽  
Static Spherically Symmetric Spacetimes

It is proved that all thin-shell wormholes built from two identical regions of vacuum static, spherically symmetric spacetimes have a negative shell surface energy density in any scalar–tensor theory of gravity with a non-ghost massless scalar field and a non-ghost graviton.

scholarly journals TURBULENT INSTABILITY OF ANTI-DE SITTER SPACE–TIME

2013 ◽  
Vol 28 (22n23) ◽  
pp. 1340020 ◽  
Author(s):  
MACIEJ MALIBORSKI ◽  
ANDRZEJ ROSTWOROWSKI
Keyword(s):  
Scalar Field ◽  
Cosmological Constant ◽  
Numerical Study ◽  
De Sitter Space ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Spherically Symmetric ◽  
De Sitter ◽  
Field System ◽  
Technical Details

In these lecture notes, we discuss recently conjectured instability of anti-de Sitter space, resulting in gravitational collapse of a large class of arbitrarily small initial perturbations. We uncover the technical details used in the numerical study of spherically symmetric Einstein-massless scalar field system with negative cosmological constant that led to the conjectured instability.

scholarly journals STATIC SPHERICALLY SYMMETRIC SCALAR FIELD SPACETIMES WITH C0 MATCHING

2011 ◽  
Vol 26 (17) ◽  
pp. 1281-1290 ◽  
Author(s):  
SWASTIK BHATTACHARYA ◽  
PANKAJ S. JOSHI
Keyword(s):  
Scalar Field ◽  
Naked Singularity ◽  
Scalar Fields ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Spherically Symmetric ◽  
Curvature Singularity ◽  
Einstein Theory ◽  
Full Class ◽  
Strong Curvature

All the classes of static massless scalar field models currently available in the Einstein theory of gravity necessarily contain a strong curvature naked singularity. We obtain here a family of solutions for static massless scalar fields coupled to gravity, which does not have any strong curvature singularity. This class of models contain a thin shell of singular matter, which has a physical interpretation. The central curvature singularity is, however, avoided which is common to all static massless scalar field spacetime models known so far. Our result thus points out that the full class of solutions in this case may contain non-singular models, which is an intriguing possibility.

scholarly journals SPHERICALLY SYMMETRIC MASSIVE SCALAR FIELDS IN GENERAL RELATIVITY

2010 ◽  
Vol 25 (07) ◽  
pp. 1429-1438 ◽  
Author(s):  
MOHAMMAD MEHRPOOYA ◽  
D. MOMENI
Keyword(s):  
Scalar Field ◽  
Cosmological Constant ◽  
Scalar Fields ◽  
Matter Field ◽  
Massless Scalar ◽  
Special Choice ◽  
Spherically Symmetric ◽  
Elementary Functions ◽  
Field Equations ◽  
Tidal Forces

First, we review some attempts made to find the exact spherically symmetric solutions to Einstein field equations in the presence of scalar fields. Wyman's solution in both the static and the nonstatic scalar field is discussed, and it is shown why in the case of the nonstatic homogenous matter field the static metric cannot be represented in terms of elementary functions. We mention here that if the space–time is static, according to field equations, there are two options for fixing the scalar field: static (time-independent) and nonstatic (time-dependent). All these solutions are limited to the minimally coupled massless scalar fields and also in the absence of the cosmological constant. Then we show that if we are interested to have homogenous isotropic scalar field matter, we can construct a series solution in terms of the scalar field's mass and cosmological constant. This solution is static and possesses a locally flat case as a special choice of the mass of the scalar field and can be interpreted as an effective vacuum. Therefore, the mass of the scalar field eliminates any locally gravitational effect as tidal forces. Finally, we describe why this system is unstable in the language of dynamical systems.

scholarly journals Hawking emission of charged particles from an electrically charged spherical black hole with scalar hair

2019 ◽  
Vol 79 (11) ◽  
Author(s):  
Avijit Chowdhury
Keyword(s):  
Black Hole ◽  
Charged Particles ◽  
Spherically Symmetric ◽  
External Observer ◽  
Scalar Charge ◽  
Dependent Part ◽  
Symmetric Black Hole ◽  
Scalar Hair ◽  
Energy Dependent ◽  
Electrically Charged

AbstractA static spherically symmetric black hole usually turns out to be either a Schwarzschild black hole or a Reissner-Nordström black hole. This result was summarised by Ruffini and Wheeler as the so-called no hair conjecture which states that for a spherically symmetric black hole only the information about mass (M) and electric charge (e) of the black hole is available for an external observer. In this work, we calculate the emission rate of charged particles from an asymptotically flat charged spherically symmetric black hole endowed with a scalar hair using a semi-classical tunneling formalism. We observe that the total entropy of the black hole contains an energy-dependent part due to the scalar charge. The upper bound on the charge-mass ratio of the emitted particles is also observed to decrease with the scalar charge as well.

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