scholarly journals Instability of spherical naked singularities of a scalar field under gravitational perturbations

2022 ◽  
Vol 120 (1) ◽  
Author(s):  
Junbin Li ◽  
Jue Liu
Keyword(s):  
Scalar Field ◽  
Naked Singularities ◽  
Gravitational Perturbations

scholarly journals Geodesic motion near self-gravitating scalar field configurations

2019 ◽  
Vol 27 (3) ◽  
pp. 231-241
Author(s):  
Ivan M. Potashov ◽  
Julia V. Tchemarina ◽  
Alexander N. Tsirulev
Keyword(s):  
Black Hole ◽  
Scalar Field ◽  
Circular Orbit ◽  
Naked Singularity ◽  
Schwarzschild Black Hole ◽  
Null Geodesics ◽  
Naked Singularities ◽  
Test Particles ◽  
Stable Circular Orbit ◽  
Innermost Stable Circular Orbit

We study the geodesics motion of neutral test particles in the static spherically symmetric spacetimes of black holes and naked singularities supported by a selfgravitating real scalar field. The scalar field is supposed to model dark matter surrounding some strongly gravitating object such as the centre of our Galaxy. The behaviour of timelike and null geodesics very close to the centre of such a configuration crucially depends on the type of spacetime. It turns out that a scalar field black hole, analogously to a Schwarzschild black hole, has the innermost stable circular orbit and the (unstable) photon sphere, but their radii are always less than the corresponding ones for the Schwarzschild black hole of the same mass; moreover, these radii can be arbitrarily small. In contrast, a scalar field naked singularity has neither the innermost stable circular orbit nor the photon sphere. Instead, such a configuration has a spherical shell of test particles surrounding its origin and remaining in quasistatic equilibrium all the time. We also show that the characteristic properties of null geodesics near the centres of a scalar field naked singularity and a scalar field black hole of the same mass are qualitatively different.

STABILITY OF SCHWARZSCHILD BLACK HOLE IN THE MASSIVE BRANS-DICKE THEORY

1986 ◽  
Vol 01 (03) ◽  
pp. 709-729 ◽  
Author(s):  
O.J. KWON ◽  
Y.D. KIM ◽  
Y.S. MYUNG ◽  
B.H. CHO ◽  
Y.J. PARK
Keyword(s):  
Black Hole ◽  
Scalar Field ◽  
Gravitational Wave ◽  
Scalar Wave ◽  
Schwarzschild Black Hole ◽  
The Real ◽  
Gravitational Perturbations ◽  
Scalar Perturbations

For the nontachyonic mass (c<0, µ2<6), we have found that all nonstatic perturbations (odd-, even-parity and scalar perturbations) allow only the real values of frequency k. This means that the black hole in the massive Brans-Dicke theory is classically stable. However, for the tachyonic mass of scalar field (c>0, µ2>6), we find that the massive Brans-Dicke theory is classically unstable. We also emphasize that the potential forms of odd-parity perturbations is simply given by the pure-gravitational perturbations. For the even-parity case, we obtain the same potential just as Zerilli’s case by combining the even-parity gravitational wave and scalar wave. For static perturbations (k=0) and c>0, only the odd- and even-parity cases with L=0, 1 is allowed to avoid exponentially growing modes.

scholarly journals NAKED SINGULARITIES IN THREE-DIMENSIONS

2003 ◽  
Vol 12 (05) ◽  
pp. 791-799
Author(s):  
G. OLIVEIRA-NETO
Keyword(s):  
Scalar Field ◽  
Analytical Solution ◽  
Cosmic Censorship ◽  
The Self ◽  
Three Dimensions ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Naked Singularities ◽  
Asymptotically Flat ◽  
Self Similar

We study an analytical solution to the Einstein's equations in (2+1)-dimensions, representing the self-similar collapse of a circularly symmetric, minimally coupled, massless, scalar field. Depending on the value of certain parameters, this solution represents the formation of naked singularities. Since our solution is asymptotically flat, these naked singularities may be relevant for the weak cosmic censorship conjecture in (2+1)-dimensions.

scholarly journals CAN BLACK HOLES DECAY TO NAKED SINGULARITIES?

2001 ◽  
Vol 10 (06) ◽  
pp. 807-809 ◽  
Author(s):  
SAURYA DAS ◽  
J. GEGENBERG ◽  
V. HUSAIN
Keyword(s):  
Black Holes ◽  
Phase Transitions ◽  
Scalar Field ◽  
Thermodynamic Properties ◽  
De Sitter ◽  
Naked Singularities ◽  
Thermodynamic Phase

We investigate thermodynamic properties of two types of asymptotically anti-de Sitter spacetimes: black holes and singular scalar field spacetimes. We describe the possibility that thermodynamic phase transitions can transform one spacetime into another, suggesting that black holes can radiate to naked singularities.

scholarly journals NAKED SINGULARITIES AND THE WILSON LOOP

2002 ◽  
Vol 17 (15n17) ◽  
pp. 955-965 ◽  
Author(s):  
VIQAR HUSAIN
Keyword(s):  
Field Theory ◽  
Black Hole ◽  
Scalar Field ◽  
Harmonic Oscillator ◽  
Wilson Loop ◽  
Boundary Theory ◽  
Topological Field Theory ◽  
Black Hole Mass ◽  
Naked Singularities ◽  
Topological Field

We give observations about dualities where one of the dual theories is geometric. These are illustrated with a duality between the simple harmonic oscillator and a topological field theory. We then discuss the Wilson loop in the context of the AdS/CFT duality. We show that the Wilson loop calculation for certain asymptotically AdS scalar field space–times with naked singularities gives results qualitatively similar to that for the AdS black hole. In particular, it is apparent that (dimensional) metric parameters in the singular space–times permit a "thermal screening" interpretation for the uark potential in the boundary theory, just like black hole mass. This suggests that the Wilson loop calculation merely captures metric parameter information rather than true horizon information.

scholarly journals INSTABILITIES OF NAKED SINGULARITIES AND BLACK HOLE INTERIORS IN GENERAL RELATIVITY

2009 ◽  
Vol 24 (08n09) ◽  
pp. 1578-1582 ◽  
Author(s):  
GUSTAVO DOTTI ◽  
REINALDO J. GLEISER ◽  
JORGE PULLIN ◽  
IGNACIO F. RANEA-SANDOVAL ◽  
HÉCTOR VUCETICH
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Recent Work ◽  
Kerr Black Hole ◽  
Cosmic Censorship ◽  
Negative Mass ◽  
Naked Singularities ◽  
Gravitational Perturbations ◽  
Inner Horizon

Metrics representing black holes in General Relativity may exhibit naked singularities for certain values of their parameters. This is the case for super-extremal (J2 > M > 0) Kerr and super-extremal (|Q| > M > 0) Reissner-Nördstrom spacetimes, and also for the negative mass Schwarzschild spacetime. We review our recent work where we show that these nakedly singular spacetimes are unstable under linear gravitational perturbations, a result that supports the cosmic censorship conjecture, and also that the inner stationary region beyond the inner horizon of a Kerr black hole (J2 < M) is linearly unstable.

Geodesic motion near self-gravitating scalar field configurations

2019 ◽  
Vol 27 (3) ◽  
pp. 231-241
Author(s):  
Ivan M. Potashov ◽  
Julia V. Tchemarina ◽  
Alexander N. Tsirulev
Keyword(s):  
Black Hole ◽  
Scalar Field ◽  
Circular Orbit ◽  
Naked Singularity ◽  
Schwarzschild Black Hole ◽  
Null Geodesics ◽  
Naked Singularities ◽  
Test Particles ◽  
Stable Circular Orbit ◽  
Innermost Stable Circular Orbit

We study the geodesics motion of neutral test particles in the static spherically symmetric spacetimes of black holes and naked singularities supported by a selfgravitating real scalar field. The scalar field is supposed to model dark matter surrounding some strongly gravitating object such as the centre of our Galaxy. The behaviour of timelike and null geodesics very close to the centre of such a configuration crucially depends on the type of spacetime. It turns out that a scalar field black hole, analogously to a Schwarzschild black hole, has the innermost stable circular orbit and the (unstable) photon sphere, but their radii are always less than the corresponding ones for the Schwarzschild black hole of the same mass; moreover, these radii can be arbitrarily small. In contrast, a scalar field naked singularity has neither the innermost stable circular orbit nor the photon sphere. Instead, such a configuration has a spherical shell of test particles surrounding its origin and remaining in quasistatic equilibrium all the time. We also show that the characteristic properties of null geodesics near the centres of a scalar field naked singularity and a scalar field black hole of the same mass are qualitatively different.

Reconstruction of f(T) gravity in the context of standard Chaplygin gas as tachyon scalar field and study of the stability against gravitational perturbation

2019 ◽  
Vol 16 (07) ◽  
pp. 1950101
Author(s):  
Surajit Chattopadhyay ◽  
Soumyodipta Karmakar
Keyword(s):  
Scalar Field ◽  
Equation Of State ◽  
State Parameter ◽  
Chaplygin Gas ◽  
Gravitational Perturbation ◽  
Gravitational Perturbations ◽  
Equation Of State Parameter ◽  
Speed Parameter ◽  
The Stability ◽  
The Universe

The present paper reports a study on the [Formula: see text] gravity reconstruction scheme in the context of considering standard Chaplygin gas as tachyon scalar field model of dark energy. The solution for reconstructed [Formula: see text] gravity has been obtained from reconstructed potential and scalar field of tachyon based on the standard Chaplygin gas. It has been observed that the equation of state parameter due to the reconstructed torsion contribution to the density and pressure behaves like quintom and is consistent with the observational value of the equation of state parameter for the current universe. The reconstructed [Formula: see text] has then been tested for gravitational perturbation by deriving the frictional term, the effective mass and the sound speed parameter for the gravitational potential and it has been found to be stable against gravitational perturbations through positive value of the squared speed of sound. Finally, statefinder diagnostics has been carried out and the reconstructed [Formula: see text] gravity is found to interpolate between dust and [Formula: see text]CDM phases of the universe.

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