scholarly journals No-scalar-hair theorem for spherically symmetric reflecting stars

2016 ◽  
Vol 94 (10) ◽  
Author(s):  
Shahar Hod
Keyword(s):  
Spherically Symmetric ◽  
Scalar Hair

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 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.

scholarly journals Spherically symmetric charged black holes with wavy scalar hair

2021 ◽  
Author(s):  
Yves Brihaye ◽  
Betti Hartmann
Keyword(s):  
Black Holes ◽  
Electromagnetic Coupling ◽  
Spherically Symmetric ◽  
Gravitational Coupling ◽  
The Novel ◽  
Maxwell Theory ◽  
Charged Black Holes ◽  
Scalar Hair ◽  
Complex Valued ◽  
Black Hole Solutions

Abstract We study standard Einstein-Maxwell theory minimally coupled to a complex valued and self-interacting scalar field. We demonstrate that new, previously unnoticed spherically symmetric, charged black hole solutions with scalar hair exist in this model for sufficiently large gravitational coupling and sufficiently small electromagnetic coupling. The novel scalar hair has the form of a spatially oscillating “wave packet” and back-reacts on the space-time such that both the Ricci and the Kretschmann scalar, respectively, possess qualitatively similar oscillations.

scholarly journals Spherically Symmetric Scalar Hair for Charged Black Holes

2020 ◽  
Vol 125 (11) ◽  
Author(s):  
Jeong-Pyong Hong ◽  
Motoo Suzuki ◽  
Masaki Yamada
Keyword(s):  
Black Holes ◽  
Spherically Symmetric ◽  
Charged Black Holes ◽  
Scalar Hair

scholarly journals Spherically symmetric black holes in f ( R ) gravity: is geometric scalar hair supported?

2016 ◽  
Vol 33 (15) ◽  
pp. 155005 ◽  
Author(s):  
Pedro Cañate ◽  
Luisa G Jaime ◽  
Marcelo Salgado
Keyword(s):  
Black Holes ◽  
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.

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